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ANALYTICAL PROCEEDINGS, JANUARY 1988. VOL 25 1 Usage and Abusage in Analysis The following are summaries of three of the papers presented at a Meeting of the Analytical Division held on May 5th, 1987, at the Scientific Societies Lecture Theatre, New Burlington Place, London W. 1. Sampling for Analysis in the Iron and Steel Industry T. S. Harrison 53 Farm View, Yateley, Camberley, Surrey GU77 7HU Iron and steel making involve the purchase of large tonnages o f raw materials from which corresponding amounts of inter- mediates and products are obtained and processed for sale. Considerable amounts of ancillaries. such as water and lubricants, are also required. Control of chemical composition by chemical and physical analytical procedures is essential for (a) process control and the production of iron and steel to close specifications, which also govern the physical properties of the material, and (b) for commercial use in assessing acceptability and in price fixing.For this purpose the “sample,” a small amount of material submitted for analysis, should be truly representative of the whole and must be prepared physically for the prescribed chemical analysis or physical technique. An analysis can only be as reliable as the sample on which it is made. An accurate result on an unrepresentative sample is meaningless and the financial implication of such error on large consignments considerable. Correct sampling is therefore important and demands judgement, skill, experience, reliabil- ity and honesty-qualities also required of the chemist. In either instance such practical ability and integrity should be well rewarded. “Sampling” covers taking the sample, delivery to the laboratory and preparation. Taking and preparation are covered later for specific cases.Delivery may be on foot, via a vehicle or by a pneumatic tube system, depending on the nature and size of the sample, and the mode and urgency of the analysis. For example, we ran two sampling vans for the collection and delivery of waters, effluents, coke oven by- products and oils in bottles. Where speed of transfer of solids was vital for urgent analysis we installed an underground network of Lamson tubes, some high-speed, with terminals in the sinter plant, blast furnace cast house. steel melting shops and central and shift stage laboratories.This system spanned a considerable area. Sampling equipment includes hammers, shovels, scoops, moulds, glass tubes, thiefs and bottles. labelled sacks and packets and labelled containers for liquids. Great care must be taken to avoid mix-ups and contamination and in some instances air must be excluded during transport, e.g., because chemical changes occur in effluents, transport must not be delayed. Preparation is carried out in a sample house, preferably within the central laboratory or a stage laboratory building and conveniently close to a metallurgical workshop. Usually on the ground floor for convenience of delivery and the siting of heavy machinery and any attendant vibration, it houses crushers, grinders, mills, hammer and slabs, rifflers and mechanical sample dividers, screens, sieves, hot-plates, drying ovens and scales for moisture determination on hygroscopic materials such as iron ores, drilling and milling machines and sample packeting facilities.The outdoor gear is also stored. Cleanli- ness is essential: suitable containers, stoppered where neces- sary, should be used to maintain sample integrity, protective clothing must be worn as necessary and the usual safety and fire precautions observed. Working in pairs is often advisable. I n contrast, in modern steel-making practice samples of liquid steel from the bath or ladle are rapidly cooled and handed or “tubed“ into the preparation room of an adjacent stage laboratory and machined by the chemists who operate automatic spectrographs. Sometimes manual sampling is replaced by mechanical sampling, e.g..of crushed iron ore, sinter mix and sinter by a sweeper arm from conveyor belts. Further. the comparatively slow taking and transport of discrete samples may be replaced by on-stream continuous sampling and analysis processes, e.g., trials were run on a radioisotope installation for sinter mix and the atomisation of liquid steel and transfer to the source unit of an automatic spectrograph. On-stream boiler water control is also a well known example. In the conventional sampling of some solid materials, several portions or increments are taken on a statistical basis. combined, well mixed and reduced to manageable size. Lumps are then comminuted and sieved to give the uniform particle size necessary for chemical dissolution or fusion.Metal drillings or millings should be fine and well mixed whilst lumps obtained by crushing, e.g., ferro-alloys, should be further crushed and sieved to uniform size. Liquids and gases are obviously treated differently. Various sampling procedures are advocated in the literature, notably in BSI and I S 0 publica- tions, which are followed by the samplers. Raw Materials and Intermediates Iron Ore and Sinter Many iron and steel works were built close to local ironstone beds from which the ore is extracted by mechanical digger in open quarries or underground mines and conveyed in rail wagons to a crusher and bedding plant. where selected wagons are sampled. Prior to this each new site is surveyed by drilling for core samples so that a quarrying or mining programme can be devised to give a uniform blend.However, the improved blast furnace technology demanded by modern L.D. and other oxygen steelmaking processes has implied supplementing local ore by imported high grade ore delivered in large bulk carriers to nearby deep water harbours for unloading, testing and sampling before rail transport to the plant. This procedure is economically viable. Commercially. the employment of a mutually agreed independent sampling body was preferred to joint sampling by representatives of each party. Each part consignment, or lot, is visually assessed for the proportions of lump, rubble and smalls and a gross sample taken to contain the sizes in these ratios. After successive2 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 crushing, mixing and reducing by coning and quartering or with a riffle divider, samples for moisture and chemical analysis are prepared.Size analyses are also made. The cargo price is based on the average Fe figure reported by both laboratories using a BS referee chemical procedure on portions of the same sample. The moisture figure obtained on site is used to convert the iron content of the dried sample to the as-received basis. Sinter is auto-sampled after the cooler, and at the bunker bottoms. Fuels: Coal Large tonnages of coal are purchased for conversion to coke, which is used in the blast furnaces to reduce iron ore to iron. In modern practice a sinter mix is made up of coke breeze and ore fines, which is then pre-ignited to sinter for charging into the furnace.Coke oven gas as a by-product is usually mixed with blast furnace gas to give a fuel used in steel-making. Correct analysis on a representative sample is very important for coke making and as a price-fixing basis and, in sampling, an appropriately designed statistical scheme should be followed. Selected waggons are sampled manually or automatically during tipping or manually from the waggon top. In the latter, increments are collected from points on the diagonals joining the waggon corners at about one sixth of the diagonal from each corner and at the centre. Samples are protected from the atmosphere and contamination and conveyed in clean, labelled sacks or tins with airtight covers when a moisture sample is to be extracted. Preparation involves particle size reduction by crushing or grinding, mixing and sample division to reduce its bulk.The end-products are finely ground, well mixed samples for complete analysis, moisture and ash determinations. Problems encountered are the loss of fine material and moisture so that constant temperature and humidity should be maintained in the work room with the exclusion of draughts. Coke Again, correct sampling and analysis and, in this instance, sampling too for physical tests is important for blast furnace control and commercial purposes as coke is often bought to supplement home production. Alternatively, any excess may be sold. Coke is preferably sampled whilst in motion or from a stopped conveyor belt, or during the unloading of waggons or lorries. Samples are made up of increments which are combined, crushed, mixed and reduced, the end-products being finely ground and well mixed for complete analysis and moisture assay and various amounts and sizes for physical tests.Moisture loss must be obviated by storage in covered tins. Errors in particle size reduction arise from contamination and segregation. The abrasive nature of coke can wear the metal surfaces of grinders and increase ash content. Hence, chro- mium steel crushing mills are advised. Segregation arising from heterogeneity influences sample division and thorough mixing is essential. Refractories Purchased refractory bricks arrive in waggons or lorries and are sampled on unloading, centrally and along the diagonals of the carrier, followed by crushing and mixing (lime, dolomite and fluorspar are autosampled from the conveyor whilst en route to storage bunkers).Occasionally used bricks, e.g., old blast furnace linings, are sampled for investigational purposes. Ferro-allo ys Ferro-alloys are added to the ladle of steel after tapping to raise the alloying element concentration to the desired level. Liquid ferro-alloys are cast into ingot-shaped moulds. After cooling and removal the material is drilled with a sharp drill, e.g., tungsten carbide tipped, from a suitable surface area pre- viously cleaned by grinding or shot blasting. Sometimes the drillings are further crushed. Undrillable material, depending on the ferro-alloy, is crushed, well mixed and sieved with coning and quartering to reduce the bulk. Segregation in bands is a major problem and all the material should pass the sieve.Sometimes further crushing in the laboratory with a manganese steel pestle and mortar is necessary, e.g., with low-carbon ferro-chromium. Ferro-molybdenum and ferro-boron segre- gate badly. Ferro-alloys are purchased on alloy content and with the expensive ferro-niobium we arranged a joint sampling system on the supplier’s premises so that any difference in analysis was the sole factor for negotiation. Other ferro-alloys are received on the works in drums or barrels which are emptied selectively, sampled and prepared as above. Products Iron and Steel Iron and steel are sampled from the liquid for process control and as solids for specification checks. The samples must be sound and free from blow holes, due regard being paid to segregation of C, P and S during solidification in the steel ingot.Here, impurities or inclusions migrate upwards to collect in a central “pipe” tapering downwards from the metal surface and the preparation is designed to avoid this region. Samples of liquid blast furnace and foundry iron are taken in a long- handled spoon from a runner in the sand floor or during pouring from a ladle, preferably when one third and two thirds of the metal has been discharged. They are poured into a 1.5-in diameter cylindrical sand mould or a split copper or steel mould often standing on a metal plate and designed also to give “pins” or “pigs” to be broken off for carbon determination by combustion. Alternatively, “pin” samples may be drawn by suction gun or rubber bulb from the spoon into glass capillary tubing of 3-mm bore.Pre-evacuated tubes are also used. Slow cooling in sand is conducive to a grey iron structure, more readily machinable, whilst rapid chilling, e.g.. in water, gives white iron, which must be crushed. Cooling in a metal mould gives a chilled surface with a grey interior. For chemical analysis after removal from the mould the sample surface is cleaned and drilled towards the axis at about one third of the height from the bottom. Air currents should be avoided as graphite fines from higher carbon iron may otherwise be lost. White iron is sliced in this position and the slice crushed, sieved and mixed. For spectrographic analysis the bottom surface is prepared by grinding. Steel “bath” samples are similarly taken from the molten bath and “pit” samples from the metal stream issuing from the ladle bottom when pouring into ingot moulds, in each instance evenly spaced throughout refining or casting.Steel is ”killed“ with aluminium wire fed in to take up oxygen, obviate blow-holes and to give a sound structure. Sometimes, the aluminium wire is placed in the mould beforehand. For steel we first used a tapered closed mould. later replaced by an open mould standing on a steel plate. Drillings for chemical analysis were obtained as for iron. “Bath” samples, being urgent, are knocked out of the mould and quenched in water, the low carbon content obviating chilling. *‘Pit” samples are removed and cooled naturally. Air blowing is sometimes used to cool iron.In either instance, for spectrographic analysis, the lower third of the sample is cut off and the cut surface of the lower portion is milled across or linished. Bath “pin” samples are sometimes taken from the spoon, either for spectrographic analysis or cut by a dual cut-off wheel into 0.75-in lengths for urgent carbon determination by combustion in an HF induc- tion furnace coupled with a thermal conductivity or infrared analyser . The much shorter refining times of modern oxygen-blown steel furnaces demanded more rapid sampling and analysis. Considerable investigation of sampling procedures, shapes and sizes took place in blast furnace cast houses and steel melting shops, the criteria being soundness, homogeneity and the maintenance of an effective seal on the spark stand of an automatic spectrograph. For steel furnace control the siting ofANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 a stage laboratory very close to the furnaces was demanded and various works aimed to achieve a minimum bath sampling, preparation and analysis cycle time.We reached that at about 2.5 min. More recently, open-ended immersion samples, capped to prevent slag ingress, have been adopted for vessel, concast tundish and ingot sampling. The mode and location of sampling solid pig iron, cast and steel product for sale is agreed between the supplier and customer. Waggons of pig iron are sampled on the diagonals system, the pigs broken or sawn and the fresh surfaces drilled in agreed positions. Pieces of white iron are broken from such a surface and crushed.Grey iron castings are surface cleaned, drilled in several places and the drillings mixed. Sometimes pieces are sawn out and cut into strips for carbon assay. White iron is drilled with a sharp drill or sliced, crushed and sieved. Sometimes the metal is first annealed to improve machinability, the decarburised skin being removed before proceeding. The location and mode of sampling steel product vary with the type of steel and dimensions. After annealing, if necessary, surface areas are cleaned and drillings or millings taken and well mixed. For spectrographic analysis pieces are sawn out and a cut surface milled. Sampling of liquid steel for oxygen, nitrogen and hydrogen determinations is fraught with difficulties. Thus, for oxygen, dipping any sampling device into the metal may alter the temperature and/or disturb the C - 0 equilibrium.Nuclei for reaction may also be introduced. Samples cast in air may pick up oxygen or oxygen might be lost by reaction during solidification. Segregation may cause heterogeneity. Some workers totally immersed a spherical mould or “bomb“ containing aluminium wire and having a disposable metal cap, which gave way and admitted the molten metal. After removal and cooling the sample was drilled for gravimetric or turbi- dimetric determination of alumina, which is related to oxygen content. Open moulds containing aluminium wire have been tried. For speed, metal “killed” in the spoon is poured into a narrow “pencil” mould, removed and rapidly water cooled. The surface is machined and cut into lengths for the vacuum fusion determination of oxygen and nitrogen.For greater speed, a “pin” sample is taken and treated as described earlier but heated in a carbon thimble in helium carrier gas and the oxygen determined as COz. For nitrogen the above methods, or an argon suction sampling probe, give samples suitable for chemical or physical determinations. After removal of oxidised surface layers steel chips prepared by milling or drilling are prepared for chemical analysis, overheating and contamination being avoided. They are stored, ideally, in hard plastic or glass sealed containers, the main precaution being to avoid contamination by nitrogen- bearing components in the laboratory atmosphere. Solid samples for instrumental methods are similarly machined with care, avoiding lubricants and other contamination. Nitrogen is also determined, preferentially, by thermal conductivity. The rapid diffusion of hydrogen in iron and steel causes severe loss during sampling, storage and preparation unless precautions are taken.Liquid steel samples must be cooled rapidly below 0 O C , followed by refrigerated storage, e.g., in cardice, and heating minimised during machining. Closed or open moulds of graphite, copper or steel are used, e.g., a split copper mould of high thermal conductivity to give a 12mm diameter cylindrical sample is recommended. The sample is removed and immediately quenched in water, surface ground and cut to about 2.5-in long with alternate cooling in water, cardice - acetone or liquid nitrogen and stored in cardice.Quenching in mercury has also been tried to entrap escaping hydrogen. Pin samples readily lose it. Porosity and entrapped slag must be avoided as they cause hydrogen loss and retention, respectively. Pores may also trap water, which can react with iron during the analysis to give hydrogen. Condensation of atmospheric moisture on the cold metal may give moisture films so that de-greasing with a solvent is practised before analysis. For solid steel the preparation and precautions are similar. Iron and Steelmaking Slags The chemical reactions occurring in the blast furnace, cupola, mixer and steel furnace produce slags by the interaction of acidic and basic radicals from the various impurities, aided by added lime. Slag floats on the metal surface and is separately tapped into ladles.When an iron bar or the long-handled spoon for steel is immersed and withdrawn slag adheres and then solidifies. It is knocked off, hammered into small pieces, ground, sieved and mixed. In each instance several samples are taken during the heat and a weighted average sometimes made. Water and Effluents The industry is concerned with the efficient usage and control of water supplies and has carried out much investigation work on this and also on its effluents arising mainly from coke oven and gas cleaning plants. Waters are classified as raw water, softened water, boiler water and effluents. In sampling, cleanliness and avoiding contamination and preserving composition, e.g., protection from evaporation, the loss of dissolved gases or the entrainment of air during handling are very important.Containers should be filled completely and clearly labelled and during transport should be protected from breakage, leakage, the entry of dust or moisture and any effect due to exposure to light (opaque or brown bottles may be desirable). This implies close-fitting stoppers for bottles and screw caps for tins and cans. All containers should be packed in boxes. Sampling in bulk of a single phase that cannot be homo- genised by shaking may be categorised as: (1) water flowing in open systems, e.g., rivers, streams and effluents; (2) those in closed systems, e.g., pipelines; (3) those in closed containers, e.g., tanks and drums; and (4) those in large open spaces, e.g., lakes and reservoirs.1. The chemical composition of a flowing water varies with the source, flow-rate, temperature, depth and pollution. Samples, e.g., of effluents, are taken with a single lunge action of a cylindrical vessel, e.g., measuring cylinder or Winchester, and several are taken, some with depth sampling devices. The temperature is recorded. 2. Closed systems show a laminar flow, the rate decreasing from the middle to the walls. Homogeneity is achieved by creating turbulence just before the sampling point, the sample being removed via a nozzle from the direction opposing flow into a collecting vessel. 3. Liquids in tanks can stratify and increments should be taken at various depths, e.g., by thiefs with plungers or by suction and mixed. Boilers may also be fitted with taps.4. Water supplies, e.g., static in lakes, may be sampled at the pumps or depth sampled and the increments mixed. Sometimes shallow waters are encountered and sampled with a shallow dish and the liquid is transferred to a measure. Some devices are continuous and automatic. Softened water is sampled from the ponds at the plant. Lubricants Care must be taken to avoid contamination, e.g., from water and dirt. Barrels are rolled and tilted to mix the oil, the screw-cap is removed and cleaned and a thief immersed, e.g., a 9 X 1.5 in i.d. cup with 3-ft holding rod. Several such samples are transferred to fill a glass bottle to the shoulder. After use the thief and glassware are cleaned with a solvent, detergent and water. Sample bottles are labelled with all necessary details.Oil systems are drained from tanks and pumps via cocks.4 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Greases These are taken with the minimum of working by pallet knife and transferred to a 7-lb tin lined with polythene and the lid is replaced. Coke Oven By-products These are sampled in metal vessels with handles and trans- ferred to bottles. Gases We use a Perspex box with two brass taps, which is purged and filled. Miscellaneous Wagons of mill-scale are sampled throughout, and deposits related to works investigations are prepared as submitted. Atmospheric Pollution Air is extracted via a meter through a funnel with filter-paper into a Drechsel bottle. The filter and bottle contents are examined. Rain gauges are also examined. The author thanks Mr.J. Dent, Chief Chemist, and Mr. W. R. Marris, Senior Assistant Chemist, British Steel Corporation, Scunthorpe, for updating this material and providing samples (iron and steel samples of varied size and shape for spectro- graphic analysis and photographic diagrams of moulds were on display after the lecture). Have You Thought About Calibrating Your AA Recently? Julian F. Tvson Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire L E I ? 3TU The Role of Calibration in the Over-all Analytical Procedure There have been several attempts in the past to provide a concise definition of “analytical chemistry.” None, apart possibly from the uninformative “analytical chemistry is what analytical chemists do,” is sufficiently all-embracing to encom- pass every aspect of the teaching, research and practice of analytical chemistry.However, many analytical chemists are involved in the exercise summarised in Fig. 1, namely the production of information about the chemical composition of a bulk material and contributing to any discussion regarding the decision to be made. The professional analytical chemist will use skill and judgement to select the most appropriate procedures to be adopted for all the intermediate stages of the analysis, namely sampling, sample preparation, test or instru- ment, calibration procedure and method of evaluation of the quality of the information that has been produced. Sampling Pre- Test or Calibration Evaluation treatment instrument Fig. 1. General scheme for the practice of analytical chemistry In evaluating the quality of the information generated, the analytical chemist will try to assess the over-all effect of the various sources of error in the procedures selected.Very often, though, the effect of the calibration procedure is ignored or overlooked and it might even be said that, if the coverage devoted to the subject in analytical text books is anything to go by, little thought is given to the calibration procedure itself, never mind its effect on the over-all accuracy and precision of the analytical procedure. Nature of the Calibration Function In addition to affecting accuracy and precision, calibration takes time and therefore has an effect on the speed of the analysis. Ideally, one would like all analytical instruments to produce a noise-free response linearly related to the amount of determinand by a known absolute relationship.which included neither terms relating to instrument operating parameters nor terms relating to sample matrix components and effects. Balances and burettes come nearest to such ideal behaviour but, of course, have other limitations in terms of selectivity and sensitivity for example, which mitigate against their being the first choice in an analytical method. In order to convert instrument response to chemical infor- mation, the off-null registration of the instrument must be calibrated. If the instrument response is, to a large extent, independent of small changes in operating parameters then this calibration does not need to be performed frequently.The calibration of a spectrophotometer for measuring the absor- bance of molecules in solution may be stable for weeks, if not months. On the other hand, if the instrument response is highly dependent on operating conditions, frequent re-calibration is necessary. A flame atomic absorption spectrometer may need almost continuous re-calibration during the working day. As with many instrumental analytical techniques, the relationship that forms the quantitative basis of the technique is only valid under a set of restrictive approximations and in any event only relates absorbance, A , to the partial pressure of the atoms. Although it is possible to modify the equation to account for the effects of unabsorbed or stray light and for ionisation, there is little benefit to the analytical chemist in doing so, as the absorbance measured is critically dependent on factors such as age of the hollow cathode lamp, fuel to oxidant ratio, observation height, nebuliser capillary and impact bead positions.No equations are available that accurately predict the relationship between absorbance and any of these paramet- ers and so the strategy of calibrating the instrument at the time of performing the analysis has to be adopted. Another difference between flame atomic absorption spec- trometry (FAAS) and solution spectrometry is that a consider- able variety of calibration curve shapes may be routinely encountered. Although such shapes will depend on the individual instrument being used, some generalisations are possible and shapes ranging from straight lines (magnesium) though various degrees of curvature (nickel) to inflections and rollovers (chromium).15 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Table 1. Calibration data . . . . . . . . . . Concentration/mg 1 - 1 0 2 4 6 8 10 Absorbance . . . . . . . . . . . . . . 0.009 0.158 0.301 0.472 0.577 0.739 Absorbance standarddeviation . . . . . . . . 0.001 0.004 0.010 0.013 0.017 0.022 Absorbance relative standard deviation. YO 11 2 3.3 2.8 2.9 3.0 . . . . Calibration Strategies for Flame Atomic Absorption Spectrometry As little information is available in text books regarding calibration procedures for FAAS, a survey by questionnaire of members of the Atomic Spectroscopy Group of the RSC Analytical Division has been conducted. Some preliminary findings from this survey have been published1 and it is clear that, although a variety of strategies are in “routine” use, it is possible to generalise to the following extent: (a) the standard additions procedure is hardly used; (b) only 33% of the analyses are considered to be interference free; (c) five calibration points (excluding the blank) are most often used (followed by three and four in popularity); (d) just under half of all curve-fitting procedures are manual (use of ruler and/or flexicurve): the remainder use a computer-based method of which the majority are the instrument’s in-built computer and algorithm; and (e) no clear optimisation procedure for selecting a strategy that is a compromise between speed, accuracy and precision emerges.Hence the procedure for routine use can be summarised as “prepare blank and up to five standards by serial dilution of stock solution, add releasing agents, etc., as appropriate, measure instrument responses, fit curve using computer-based method and enter responses for unknowns to allow computer to calculate concentrations.” Any calibration procedure affects the over-all analysis in- terms of speed, accuracy and precision.The number of calibration points ~ the recalibration frequency and the measurement time are all factors to be considered in deciding how long analysis times will be. How well matched the samples and standards are and how closely the fitted curve matches the true curve are both factors which will affect the accuracy. Also, in addition to the uncertainty due to instrument response fluctuations, the uncertainty of the curve-fitting procedure will contribute to the precision obtained.This latter contribution to the over-all “plus or minus” term is usually ignored, although in FAAS it may be substantial.3 Uncertainty in the Curve-fitting Procedure One of the reasons that the uncertainty in the curve-fitting procedure is ignored is that it is difficult to calculate a confidence interval about an interpolated concentration value as the appropriate equations are not readily available. It should also be noted that not all of the commercially available algorithms for FAAS are based on least-squares regression procedures. Several involve procedures which force the curve to pass through the calibration points.Textbooks concerned with statistical methods for analytical chemistsJ.5 give only the relevant equations for confidence limits based on least-squares regression procedures for straight lines. However, a considera- tion of this situation is instructive. Linear Least Squares Regression Some hypothetical calibration data6 are given in Table 1, for which a least-squares regression analysis gives slope 0.0725 and intercept 0.0133 and correlation coefficient 0.9988. Confidence limits (CL) about a calculation concentration value may be obtained from the equation where r is a value found from tables, b is the slope, rn is the number of sample preparations and measurements made to establish yo, the experimental value of y from which the concentration is to be calculated, n is the number of points, is the mean y value, x i is an individual x value, X is the mean x value and s,./.~ is given by the equation where y , is an individual y value and pi is the point on the calculated regression line corresponding to the value of x,.For two unknowns whose absorbance values are 0.100 and 0.600, the corresponding concentrations are 1.20 k 0.65 and 8.09 k 0.63 mg 1-1, where the k values are %”/o confidence intervals. These confidence intervals are uncomfortably large for the results of a technique that is widely described as capable of making measurements with coefficients of variation well below 2”/0 for most of the useful working range.’ The problem is that the uncertainty produced by the process of fitting a straight line to the calibration points is not influenced by the uncertainty in the individual absorbance values.Provided that the mean absorbance readings remain the same, the same calibration function is Calculated regardless of how large the standard deviations of the readings are. Weighted Linear Least-squares Regression The situation can be improved by the use of a weighted regression procedure. The procedure accounts for the observa- tion that standard deviation of the absorbance readings increases with increasing absorbance and thus a more realistic calibration function will be obtained if the fitting procedure gives more weight to the points at low absorbance than it does to those at higher absorbance. A commonly adopted pro- cedureH.9 is to weight points by factors proportional to the reciprocal of the variance, scaled so that the sum of the weighting factors equals the number of data points.The slope and intercept of the weighted regression line are 0.0738 and 0.0091, respectively (not very different from the unweighted line), but the 95% confidence interval for the unknowns of absorbance 0.100 and 0.600 are now 1.23 k 0.12 and 8.01 k 0.72 mg 1 - 1 , respectively. However, only one commercially available algorithm uses a weighting procedure, and thus an evaluation of fitting algorithms is difficult. Table 2. Uncertainty to be quoted with mean of replicate analyses n 2 3 4 5 6 7 tin:- . . 8.99 2.48 1.59 1.24 1.05 0.93 . . . . * The 95% confidence interval is [sin:, where the value off is found from tables and depends on the percentage and number of results.When r/ni < 1. the 95% confidence interval is < s. Comparison of Curve Fitting Algorithms The results of a comparison of curve-fitting algorithms’ based on how closely the fitted curve passed to measured points between the calibration points produced the following general conclusions: (a) with one or two exceptions all algorithms have, on the whole, similar performances; (b) performance does6 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 depend on curve shape (i.e., the element being determined, etc.) and the number of points, better perforriance being obtained for all algorithms for straight calibrations with more points; (c) some algorithms are better than others for dealing with curved calibrations; (d) manual methods (linear segments and fitting by eye) are worse than computer-based methods; and (e) as a rough guide, a commercially available curve-fitting procedure for AAS produces an uncertainty of between 2 and 5% when used with blank and three standards or blank and four standards.Reporting Results Uncertainties in the curve fit will give rise to even larger uncertainties when reporting the results of “recovery” studies. The basis of such calculations appears to be: analyse the sample (X mg 1-I), add a spike ( Y mg 1-1) and re-analyse (2 mg 1-I), calculate the percentage recovery, %R, as 100 Zl(X + Y) and establish an uncertainty in this value by replication of the procedure. It seems to be common practice to assume that there is no uncertainty associated with X and Z. It should be Table 3.Analysis of a standard reference material Trace element No. of content/mg kg- No. of analyses per Element sub-samples sub-sample* Certified Foundt Cd . . 4 4 0.27 k 0.04 0.27 k 0.002 Pb . . 4 4 0.34 5 0.08 0.33 k 0.009 * Performed on separate days. + At the 95% confidence limit. borne in mind that if both Xand Z have an uncertainty of -t5% then %R will have an uncertainty of k7%. When quoting results of replicate analyses, the uncertainty can be expressed as either ks, the standard deviation, or ? the 95% confidence limits. There is an understandable tendency on the part of authors to adopt whichever value is numerically the smaller. As a guide for authors the relevant data are given in Table 2, which shows that for the 95% confidence limits, +s should be quoted for n < 7 and the &95% confidence interval for n > 7. This rule is well illustrated in Tables 3 and 4, taken from the recent literature. Despite the fact that this procedure used linear regression on a blank and three standards, the uncertainty in the results quoted is remarkable and apparently much better than the uncertainty in the certificate values.The role of the calibration procedure certainly deserves at least a second thought. Table 4. Recovery of trace elements added No. of Amount Recovery Element determinations addedlpg & s.d.. ‘/o Cd . . . . 4 0.4 94.6 2 0.9 Pb . . . . 4 0.5 96.8 k 1.2 Help with aspects of the work described here from Mr. S. R. Bysouth is gratefully acknowledged, as is financial support for him from the Trustees of the Analytical Division Trust Fund in the form of a SAC Research Studentship. 1.2. 3. 4. 5 . 6. 7 . 8. 9. References Thompson, K. C.. Analyst, 1978. 103, 1258. Tyson, J . F., and Bysouth, S. R.. Anal. Proc.. 1987. 24, 83. Bysouth, S. R., and Tyson, J . F., I . Anal. At. Spectrom., 1986, 1, 85. Caulcutt. R., and Boddy, R., ”Statistics for Analytical Chemists,” Chapman and Hall. London. 1983. Miller, J . C., and Miller, J . N . , “Statistics for Analytical Chemistry,” Ellis Horwood. Chichester, 1984. Miller. J . C., and Miller, J . N . . “Statistics for Analytical Chemistry,” Ellis Horwood, Chichester, 1984, p. 109. Price. N . J . , “Spectrochemical Analysis by Atomic Absorp- tion,” Heyden, London, 1979, p. 155. Caulcutt, R.. and Boddy, R., “Statistics for Analytical Chem- ists,” Chapman and Hall, London, 1983, p.103. Miller, J . C., and Miller. J . N.. “Statistics for Analytical Chemistry,” Ellis Horwood, Chichester. 1984. p. 107. Constant Good Sense H. S. Rossotti St. Anne‘s College, Oxford OX2 6HS Equilibrium chemists, seeking research grants or publication, often claim that detailed knowledge of the many equilibria involved in a chemical analysis is a prerequisite for respectable analytical chemistry. The imaginary analyst, armed with equilibrium constants measured under the exact conditions he or she wishes to use, can thus design an ideally accurate, precise and specific procedure. Real analysts may indeed wish to use protonation and stability constants in order to develop more effective methods, but it is unlikely that these were obtained under conditions identical with those they wish to use.As it is even less likely that the analyst has the time or inclination to measure the values for himself, he sensibly turns to compilations of data. He has three main choices: (i) to confront all measurements’ made up until 1973, and to pick from the raw data the values he thinks most appropriate, without guidance from the compilers; (ii) to make use of the computer’s judgement2 (together with values obtained by interpolation and educated prediction) for a more limited range of ligands under popularly studied condi- tions; or (iii) to use visual data,3 admirably‘ displayed as diagrams showing the effect of pH on species distribution. How should the analyst select his information from this plethora of raw, processed and predigested equilibrium chem- istry? And what will be the effect if he chooses unwisely? The most important step is to ensure that the constant chosen refers to the right reaction; comparison of the symbols used in references 1 and 3 shows that some talent in decoding is helpful.Many equilibria have been studied by several groups of workers, sometimes each under similar conditions; the analyst will soon acquire the judgement, and prejudice, to recognise quality and to pick the more reliable values from compilations of raw data. Probably, however, there is no value, reliable or suspect, which has been measured under the exact conditions the analyst needs. Most analytical chemists are concerned with the complete- ness of a change, be it a precipitation of a homogeneous titration, colour change or masking reaction.To this end theyANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 7 Table 1. Some symbols for stability Species React ion Constant4 ML,, . . . . M + HL-ML,, ML,, I + L+ ML,, Ref. 1: n = 1.2, 3; PI. fi2. p3. Ref. 3“: Po, ~ O o , ~ l ~ O o Ref. 1: n = 1,2,3; K , , K 2 , K3. Ref. 3: (30. ( ~ O ~ l $ ~ , ; I-hoo/ho Ref 3: PI, Ref. 3: P,,,, Ref. 3: P,,,,<.t M,H,,L,, . . . . 4M + p H + nL-+ M,H,]L,, Many workers : B,/,,,, M + H,,L- MH,,L M + H,,L + H/,L + MH,,. hL2 M + H,,L + H/,L + H,.L + MH,,+h + , Li * In ref. 1. + 4 Similar vigilance is needed for the symbol a. Analytical chemists4 define a side-reaction coefficient = I$,(, = Pflll(l = 1. (in ref. 3) = [.S,,,, (in ref.1). Q‘M = (Mt<,t - ~[MP,,I)”l = ~[M,S,,II[Ml where the ligand P is that involved in the primary analytical reaction, and the various j s are those involved in side-reactions. Equilibrium chemists, describing the simple system M. L. define 0, [ML,.]/M,,,c = [ML l/x:[ML,,J use values of “conditional” constants-‘ valid only under particular conditions. Suppose that a single complex ML (of stability constant K = [ML]I[M][L]) is formed, in the presence of protonated ligands H,L. The conditional stability constant of ML is defined as K’ = [MLI/(MlO, - [MLl)(LtOt - [H,LI) Clearly, the denominator, and hence K’, is a function of pH. More complex expressions can be derived if the metal ion is hydrolysed, or if higher binary complexes ML, or tertiary complexes ML,H, or MLJOH),, are formed; but in each instance the conditional constant is related to the true value by some function of the total concentrations, the pH and the true formation constant of all other species present.For the satisfactorily “complete” formation of the 1 : 1 complex ML under normal analytical conditions, a conditional constant of K ; > 108 will usually suffice, but in practice the analyst often has several powers of ten in hand. Any variation in the composition of the medium or in the temperature will of course affect the (true) formation constants of all species present, and so will have a complicated effect on the function K ; (pH). Here, the effect of choice of constant on the function is considered. Self-consistent values of protona- tion constants and stability constants were used to calculate the conditional constant K,: (of ML,,) as a function of pH for a number of systems in order to assess the effect of any differences between values obtained (i) under identical condi- tions by different authors, (ii) values for the same ionic strength for different electrolytes, (iii) for different ionic strengths, (iv) for different temperatures, and (v) for different solvents.Predictably, changes in conditions produce changes in conditional constants, but not gross changes. Good sense would suggest that, if possible, conditions should be chosen so that KA > 109. The analyst will then have one power of ten in hand, and this should be more than enough to make good the variations (all appreciably less than a factor of ten) which occur even with such large changes as in ionic strength from 0.1 to 1.0 M or in temperature from 30 to 50 “C. Naturally, exchanging 0.1 M KN03 for 0.1 M NaClO-‘ produced only a very small effect. Again, predictably, an appreciable change in K:, results from a change in the composition of the solvent: at about pH 9, log KI, for nickel acetylacetonate in aqueous ethanol of molar fraction 0.517 is nearly 3 log units above the value in water; but then no analyst with good sense would take values for one solvent and apply them to another. Hence, it seems as if the most sensible procedure is to choose conditions in which the calculated value of KA > 109, and take the justifiably optimistic view that little harm will be done to the analytical method by those variations which occur through use of different condi- tions or somewhat faulty constants, provided that solvent itself is unchanged; and that proper vigilance is maintained. There is one caveat, however. All the calculations discussed so far involved constants, which, like most of the values available, had been determined with a glass electrode. Results obtained for the same system were well within our safety margin of a factor of ten. Other methods may yield wider unwelcome variety. The system Ce4+ - EDTA has been studied at 20°C and I = 1 . 0 ~ by several workers.’ The values of K I (“true”) obtained spectrophotometrically varied by eight powers of ten, with a range log K 1 = 22.4 f 4.0. Even with the same electrolyte [(NH&S04], values obtained by different workers differed by two powers of ten. It seems that the relaxed common-sense approach recommended here is best restricted to those constants obtained using a glass electrode, or other potentiometric technique. References 1. Sillen, L. (3.. and Martell, A , E., 5tability Constants of Metal - Ion Complexes,” Chemical Society, London. 1964; Hogfeldt, E., IUPAC Supplements to above, Pergamon Press, Oxford. 1979, 1982. Martell. A. E . . and Smith, R. M., ”Critical Stability Constants.” Plenum Press, New York, 1974. Kragten, J . , “Atlas of Metal - Ligand Equilibria in Aqueous Solution,” Ellis Horwood, Chichester. 1978. Ringbom, A . , “Complexation of Analytical Chemistry.” Inter- science, New York, 1963. 2. 3. 4.

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January 1988 ANPRDI 25( 1) 1-32 (1 988) Analytical Proceedings Proceedings of the Analytical Division of The Royal Society of Chemistry CONTENTS 1 Summaries of Papers 1 'Usage and Abusage in Analysis' 'Particles in Hot Gases-Sampling and Sample Preparation' 'Di-5 'New Developments and Applications of Thermal Analysis' 8 19 22 Equipment News 26 Ve r ein Deu tsc her I ng en ieu r e G u id el i n es 28 New British Standards 28 Publications Received 30 Conferences and Meetings 30 Courses 32 Analytical Division Diary Edited by L. Bretherick 5 ='-- Hazards in the Chemical Laboratory Safety has Consultant become established as an essential handbook of safetv oractices. measures and toxic effects for laboratories handliig dangerous chemicals. Since the last edition was published in 1981 there have been many changes in legislation, regulations, precautionary safety methods and toxicity assessments which warrant publication of this new 4th edition. In addition coverage has been expanded to include material relating to legislation and safety practices in the USA. Protective PVC Binding 618pp ISBN 0 85186 489 9 Price €2950 ($54.00) RSC Members Price €18.00 Society ORDERING of Chemistry, RSC Members Membership should send Manager, their orders 30 Russell to: The Square, Royal f SOCIETY ROYAL OF London WClB 5DT, UK. Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 lHN, UK. ed CHEMISTRY lnformat ion Services Typeset and printed by Black Bear Press Limited, Cambridge, England

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8 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 New Developments and Applications of Thermal Analysis The following are summaries of six of the papers presented at the Annual General Meeting of the Thermal Methods Group held on November 13-14th, 1986, at the Bonnington Hotel, Southampton Row, London WCI. Some Applications of Thermal Analysis to Cement Hydrates S. M. Bushnell-Watson, H. D. Winbow and J. H. Sharp Department of Ceramics, Glasses and Polymers, University of Sheffield, Sheffield S I0 2TN Hydrates are of general interest, but are technologically important as the products of the hydration of cements. During our investigations into the chemistry of hydration of several special cements. we have used thermal methods, especially DTA, extensively. These techniques provide a sensitive method for the detection of hydrates and are particularly valuable when phases amorphous to X-rays are formed.Problems of identification arise, however, because the tem- peratures at which dehydration reactions are observed vary markedly with the amount of the hydrate present and procedural variables associated with the apparatus used. Overlapping peaks are frequently encountered and are not always clearly resolved. It is essential, therefore, to use thermal methods in conjunction with other techniques, of which X-ray powder diffraction (XRD) and scanning electron microscopy are perhaps the most important. DATA and TG curves have frequently been obtained as an integral part of the study of the formation of C-S-H gel and Ca(OH)2 in Portland cement pastes and the hydration of ciment fondu [high-alumina cement (HAC) with an A1203 content of approximately 40%].We have extended the application of these techniques to investigate the hydration of refractory HAC with 5&80% A1203, and magnesia - phos- phate cements which are used as repair materials because of their rapid hardening properties. Usually the combination of XRD and DTA leads to a reliable identification of the hydrates formed and at least a semi-quantitative estimation of their amounts. We have, however, made several intriguing observa- tions that may be of interest to others besides cement chemists. Magnesia - phosphate cementsl.2 are formed by the reactions between magnesia and ammonium dihydrogen phosphate (ADP) in the presence of sodium tripolyphosphate: Schertelite MgO + 2NHjH,PO,+ 3HzO=(NH4)zMg(HP01)2.4HIO MgO + (NHj):Mg(HPOj):.4H20 + 7H20 = 2NTljMgPOj.6Hz0 Struvite Schertelite and struvite are both readily identified as reaction products by means of XRD. When a sample of pure struvite is heated, it loses five molecules of water at around 100 "C and the last molecule at about 23OoC,3..J as shown in Fig. 1A. When struvite is diluted with an excess of quartz sand (as i n a mortar or concrete), usually only five molecules of water are lost at around 100 "C (Fig. lB), but sometimes all six molecules are apparently lost simultaneously (Fig. 1C). The bar charts on the figure represent the XRD peak intensities of struvite (stj, schertelite (sc) and ADP (a). Reaction products containing both struvite and schertelite (and sometimes unreacted ADP as well) give rise to a double endotherm (Fig.lD), but often the DTA curve is more complex, such as that shown in Fig. lE, which is clearly an exotherm superimposed on an endotherm or endotherms. We believe that the presence of the exotherm is evidence for the following reactions: MgO + (NH4)2Mg(HP04)2.4HIO = NH4MgP04.HIO + 3Hz0 Dittmarite MgO + NH4H2POA = NH4MgPOj.HIO A \ I / - - - 1501 D \ I Fig. 1. DTA curves and XRD bar charts of (A) pure struvite (ATat half-sensitivity) and (B-E) various magnesia - phosphate cement mortars hydrated for 3 h at 25 "CANALYTICAL PROCEEDINGS, JANUARY 1988. VOL 25 9 The formation of dittmarite by these routes, in addition to that from struvite. explains the enhanced intensity of the endother- mic peak at 256 "C.The refractory calcium aluminate cements are similar to ciment fondu in that the major active component is CaA1204 or CA (C = CaO, A = A1203, H = H,O), and the principal hydration products, which vary with temperature and duration of hydration, are CAHlo, C2AH8, C3AHhr AH, gel and crystalline AH3. Problems in resolving the peaks at 100-160 "C (due to AH, gel and CAHIO) and at 270-330°C (due to AH3 and C3AH6) are well known to thermal analysts.5 A less intense peak is usually present in the DTA curve of refractory calcium aluminate cements at around 190°C and this some- times appears as a doublet (Fig. 2). Although this peak is 33 1 Fig. 2. DTA curves and XRD bar charts of hydration products of Secar 51 (25 g ) + CaCO: ( 5 g) + H,O (15 ml) at 10°C after (A) 7 h.(B) 1 d , (C) 2 d and (D) 5 d frequently attributed to the dehydration of C;AHH, we have alreaiy suggested that it can also indicate the presence of C4ACH11,6 where C = C 0 2 . In refractory cements with intermediate Al2O3 contents (5&60%), gehlenite, C2AS, is present as a minor phase which hydratesrito form stratlingite ~ C2ASH8. When HAC is hydrated in the presence of LiCl (which acts as a spectacular accelerator of the set) we have observed the presence of C4AHI3 in the hydrated paste by XRD. Both of these hydrates give endothermic peaks on heating, which can occur at around 190°C when they are present in only small amounts. The presence of double peaks or shoulders on a main peak (as shown in Fig. 2) in this temperature region is, therefore, to be expected.It is essential to use XRD or some other technique to establish which phase or mixture of phases is causing the thermal effect and it seems certain that errors of attribution have been made in the published literature. On the other hand, the bar charts shown in Figs. 2 and 3 indicate that the XRD peaks of these fresh cement pastes are relatively weak. The DTA curves, represent- ing amorphous as well as crystalline hydrates, provide much additional information. The DTA curves shown in Fig. 2 also show an interesting observation made repeatedly in our work and also by others,'.g but generally disregarded. The expected doublet at 270-330 "C attributed to the presence of AH3 and C3AHh is sometimes observed as a triplet. We strongly suspect, from comparison of the relative intensities of our XRD and DTA peaks due to gibbsite, that amorphous AH3 in addition to crystalline gibbsite is formed in fresh HAC pastes.This could account for the relative weakening of the peak at 279-290°C in Fig. 2, as the hydration products crystallise. The DTA curves shown in Fig. 3, however, indicate that sometimes it is the middle peak 300 300 Fig. 3. DTA curves and XRD bar charts of hydration products of ( A ) Secar 51 with w : c = 0.5 at 30°C after 5 . 6 and 7 d. (B) Secar 71 with w : c = 0.5 at 50°C: after 1 . 2 and 3 h and (C) Secar 71 with w : c = 0.5 at 40 "C after 7, 16 and 24 h that disappears with increasing duration of hydration. As it is most unlikely that an amorphous form of AH3 would give a DTA peak at a higher temperature than a crystalline poly- morph, an alternative explanation must be sought.Possible explanations are that the peaks are due either to the presence of two crystalline forms of AH3 and one of C3AH6 or to gibbsite and two forms of C3AH6, one of which would seem to be an amorphous prototype formed during the conversion process. Work is continuing to try to resolve this matter. References 1. El-Jazairi, B., Concrete, 1982, 12. 2. Abdelrazig, B. E . I., Sharp. J. H., Siddy, P. A , . and El-Jazairi, B., Proc. Br. Ceram. Soc., 1984, 35, 141. 3. Paulik, J . , andPaulik, F . , Proc. 4th Int. Conf. ThermalAnalysis, Budupest, 1974, 3 , 789.10 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 4. 5 . Abdelrazig, B. E. I.. and Sharp. J . H., Thermochim.Acta, in the press. 1985, 93, 613. Wilburn, F. W., Keattch, C . J., Midgley, H. G., and Charsley, E. L.. "Recommendations for the Testing of High Alumina Cement Concrete Samples by Thermoanalytical Techniques," Thermal Methods Group. Chemical Society, London, 1975. 6. 7. Bushnell-Watson, S. M. and Sharp. J . H., Thermochim Actu. Murat. M., in "Proceedings of the International Seminar on Calcium Aluminates. Turin. 1982." Polytechnic0 di Torino. Turin, 1982, pp. 59-84. Midgley, H. G., personal communication. 8. Arrhenius-Right or Wrong? D. Dollimore Department of Chemistry, University of Toledo, Toledo, OH, USA The Arrhenius equation is used as a "corner stone" in kinetic analysis in spite of the fact that a sizeable fraction of results collected, especially in solid-state decomposition, show deviant behaviour.Frost and Pearson1 list a series of deviant behaviour patterns, but the most common deviant behaviour is several linear regions in the plot of log (rate constant) against reciprocal temperature (in degrees Kelvin), or even a continu- ous curve which can be regarded as an infinite collection of linear regions. The relationship A' T log K = - + constant where K is a specific reaction rate. T is the temperature in degrees Kelvin and A ' is a constant, was first put forward by Hood.' It was opposed by Harcourt and Essen,3 who claimed the relationship was where rn is positive. the form we now recognise as the Arrhenius equation: K = constant X Arrheniusj used the van't Hoff relationship' as the basis for E RT l n K = - - + l n A or where A is the pre-exponential factor and exp (-EIRT) is proportional to the number of molecules possessing energy E in excess of the average energy characteristic of all molecules in the system at the temperature T. There are difficulties in thoughtfully applying this equation to polymers and certain other systems because of an inability to identify the mole in the definition of the units of E as kilojoules per mole.This arises because in the calculation of E from the Arrhenius plot the slope is divided by the appropriate value of the gas constant R. In making the application of the Arrhenius equation to solid-state reactions one is further hampered by the absence of a concentration term and the consequence of the K = A e-ERT dependence of the kinetic laws on geometric factors controlling the process at a reaction interface.This leads to a nomenclature where one deals with the fraction decomposed ( a ) when the specific reaction rate ( k ) is defined as d a dr - = kf(@ where r is the time andf(a) some function of a.0 For this to be an acceptable rate constant, then as CY + 0, f ( a ) + 1 and daidr = k . However. many solid-state kinetic laws instead show that as a + 0, then f ( a ) + 0 when daidr = 0 and k is not a specific reaction rate constant. This difficulty is removed by normalis- ing at a = 0.5.7 The occurrence in many instances of Arrhenius plots showing two or more linear regions8 or a curve.9 however, demonstrates an absolute need for rising tempera- ture methods of establishing kinetics to be portrayed in the form of an Arrhenius plot of log k against ZIT.This is often ignored in the application of these methods, which are often implicitly based on there being only a single set of Arrhenius parameters. 1. 2. 3. 4. 5. 6. 7. 8. 9. References Frost. A. A.. and Pearson. R. G.. "Kinetics and Mechanism." Wiley. New York. 1953, p. 23. Hood, J . J . . Phil. Max.. 1878, 6, 731: 1885. 20. 323. Harcourt. A. V.. and Essen. W.. Phil. Truris. R. Soc. London, Ser. A . 1895, 186. 187; 1913. 212. 187. Arrhenius, S . . Z . Phys. Chem.. 1889. 4. 226. van't Hoff. J . H.. "Etudes de Dynamique Chemique." Muller. Amsterdam, 1884. Dollimore. D . , Heal. G. R.. and Krupay. R. W., Thermochim. Actci. 1978, 24. 293. Fatemi. N.. Whitehead. R.. Price. D.. and Dollimore. D.. Thermochirn.Acta., 1986. 104, 93. Dollimore. D.. and Rodgers. P. F.. Thermochim. Actu. 1979. 30, 273. Mikhail, R . Sh., Dollimore. D.. Kame], A. M.. and El-Nazer. N. R.. J. Appl. Chem. Riotechriol.. 1973. 23. 419. Use of Thermal Analysis in Coal Energy Studies Alexandra de Koranyi British Gas Corporation, Research and Development Division, Michael Road, London S W6 2AD Owing to the depletion of oil and gas resources that is occurring throughout the world, there is renewed interest in more efficient use of the vast reserves of coal that exist worldwide. There are four main areas of coal utilisation: pyrolysis or carbonisation, combustion, gasification and liquefaction. In order to use coal efficiently, it is important to understand the complex structure and properties of coal.Experimental techniques to study and define these properties quantitatively are still being developed, while thermoanalysis is continuing to contribute to coal research and process analysis. Coal Characterisation Coal contains mostly carbon, together with ash or mineral matter, in addition to tars, hydrogen and volatiles. The most important minerals are the clay minerals and carbonates. Coal ranking depends on a knowledge of its proximate and ultimate analysis. Proximate analysis of coal is a determination of the moisture, ash and volatile matter content of the coal sample,' and is obtained by heating the coal under a set of standard conditions. Proximate analysis of coals routinely usedANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 11 to take about 1 d to complete but the use of thermal analysis has reduced this time to 1 h.Ultimate analysis is an absolute measure of the elemental composition of coal.' Evaluation of mineral matter in coal is important and is derived indirectly from the ash content remaining after high-temperature combustion. Low-temperature ashing of coals removes the organic carbon from coal preferentially by reacting the coal in an oxygen plasma at temperatures up to 250 "C without major alteration of the inorganic content. The minerals are then determined directly by thermal analysis. Sulphur found in coal ash has many detrimental effects on fuel properties.' A common sulphide mineral in coal is pyrite (FeS2), which may be determined using thermomagnet- ometrya2 In this technique, a magnet is sited within a thermobalance which is used to measure the magnetic attrac- tion of iron in pyrite.When combined with thermogravimetry (TG), thermomagnetometry is a useful method of analysis. However, when siderite (FeC03) is present in coal together with pyrite, the use of evolved gas analysis3 will determine umambiguously the pyrite content by measuring directly the SO2 evolved from it. The clay minerals and carbonates found in coal exhibit strong endothermic decompositions4 and can be analysed by differential scanning calorimetry (DSC), which can also potentially measure char reactivity. Differential thermal analysis (DTA) and differential ther- mogravimetry (DTG) are used to establish the behaviour of mineral matter on heating in different atmospheres.Multiple atmosphere DTA and TG will separate many thermal analysis peaks, affording better identification. Pyrolysis (Carbonisation) Pyrolysis of raw coals in an inert atmosphere leads to a loss of the so-called volatile matter and leaves behind a solid, highly porous char. TG and DTG5 have been used in tests developed recently to assess the temperature a coal has been subjected to in a gasifier, and also to "fingerprint" individual coal devolatil- isation characteristics. Kinetics of carbonisation can also be studied. Emanation thermal analysis (ETA) is a thermoanaly- tical method based on the rate of release of z2oRn by heating samples previously labelled with radium parent isotopes.6 When used in conjunction with DTG and porosity measure- ments, detailed information on coal structural changes occur- ring7 during pyrolysis can be obtained.Low-temperature carbonisation (below 700 "C) has been used to make smokeless solid fuel for domestic consumption. High-temperature car- bonisation (above 900'C) gives a less reactive char of lower porosity. This process has been used for centuries for the production of metallurgical coke. When a coal is heated rapidly, a higher proportion of volatiles can be released. This process of rapid heating of coal in an inert atmosphere is known as flash pyrolysis or, when carried out in a hydrogen atmosphere, flash hydropyrolysis. These methods have been proposed for conversion of coal to gaseous and liquid fuels. Numerous products can also be derived from coals. In fact, next to combustion, carbonisation is the greatest use made of coal.Combustion Of the four areas of coal utilisation, the largest is combustion. Combustion may be defined as high-temperature oxidation of carbon and hydrocarbons to carbon dioxide and water with an accompanying release of heat.8 Combustion is used mainly for electricity generation. The most recent method of combustion is fluidised bed combustion (FBC). FBC produces a higher heat release rate and heat transfer rate within the bed than other combustion systems' and, therefore, lower temperatures can be used, resulting in the need for less coal to sustain combustion due to efficient burning. Boiler costs and corrosion are also reduced and a wider variety of fuels can, therefore, be burned. In combustion systems for power generation, the emission of oxides of sulphur is an environmental problem which can be solved by the addition of limestone in FBC.Thermal methods of analysis can be used to monitor the efficiency of these coal combustion processes.9 Potentially a more attractive process for power generation is FBC at high pressure, but this process is still in the experimental stage. Ash layers can be monitored by DTG and TG. DTG can also measure the dissociation features of coal while databanks can be developed for assessment of coal combustion characteristics. Gasification Over the past 200 years, gasworks have been commonly seen throughout Western Europe producing gas from carbonisa- tion. Gasification combines the thermal decomposition of coal with reaction of the resulting char with reactive atmospheres yielding fuel gas.Coal gasification results in complete conver- sion of all the carbon in coal to gas products. Gasification can be performed in various ways and the resulting combustible gases can be of low, medium or high calorific value (CV). Medium CV gas (ca. 300BTU per standard cubic foot) can be used for power generation and other industrial uses, while high CV gas (1000 BTU per standard cubic foot) is interchangeable with natural gas and is used as the basis of substitute natural gas (SNG). Research into the fundamental aspects of coal gasification, such as the kinetics of gasification, has improved efficiency. However, further improvements in performance can be obtained by the use of catalysts. Again, research in this area of coal gasification is taking place with the aid of thermogravi- metric techniques. Liquefaction Coal liquefaction processes involve the addition of a solvent prior to heating the coal to the desired temperature, generally 40G50O"C.l Solvent extraction is a mild form of chemical conversion.The yield of extract is enhanced by temperature and the presence of hydrogen. The underlying problem in liquefaction is to increase the hydrogen to carbon ratio in the products cheaply and various processes are being developed for this purpose. Commercial liquid fuels can be produced by such rapid pyrolysis processes as the US Cogas process, or indirectly by gasification to a synthesis gas, followed by appropriate catalytic processes, as in South Africa's SASOL plant. Mineral matter present in coal can act as a catalyst in any of the utilisation processes. In the liquefaction process, the rate of liquefaction increases directly with the concentration of mineral matter,3 depending on the composition.Using mul- tiple atmosphere DTA and TG, coals can be assessed for chemical properties and reactivity to determine their stability as a source of liquid fuels. Fundamental Research Even though gas - carbon reactions have been a part of our industrial economy for decades, a basic understanding of the reaction mechanisms and kinetics involved has lagged far behind their practical use, However, much research is now going on in these areas, increasing our understanding of gas - solid interactions. Models to describe mass transport and the heterogeneous chemistry which occurs during coal pyrolysis and gasification are being developed. One of the most complete models on microscopic pore diffusion is the pore tree structure model developed recently by Simons.* ( J Such models reflect in detail the essence of over-all char reactions. Mechanisms have also been developed to describe gasification or combustion interactions, such as the shrinking core model11 and the two-dimensional coal gasification or DICOG model. l 2 These put theories on the solid basis of a mathematical model. Thermal methods of analysis can be useful in elucidating these12 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 interactions by conferring a sound experimental footing to theory and indicating directions for further expansion and validation of the models.The concepts of active surface area and active site concentra- tions are of equal importance in understanding the kinetics of coal gasification and combustion. Thermal analysis can deter- mine the fine pore structure of a char or the total surface area accessible to reactants. Intrinsic reactivity of a coal char is related to the number of active sites which can be measured by various methods, such as in the recent method developed by Causton and McEnaney13 involving oxygen chemisorption followed by temperature-programmed desorption. More work needs to be done in the area of reactivity of different coal chars with oxygen, steam and hydrogen, and also in high-pressure gasification where reactivity data are sparse. The thermobalance is especially useful in obtaining reactivity data as gasification reaction rates can be measured directly under differential conditions in a constant, well defined environment during reaction. Conclusions The potential use of thermoanalytical techniques in the field of coal characterisation and reaction is enormous.We have seen in this brief review only a small part of the usefulness of these methods in the area of coal energy studies. However, with further work and increased understanding of coal utilisation, the vast resources of this fossil fuel can be used with greater efficiency for the benefit of mankind. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. References Speight, J. G., “The Chemistry and Technology of Coal,” Marcel Dekker, New York, 1983. Aylmer, D. M., and Rowe, M.W., Thermochim. Acta, 1984, 78, 81. Warne, S. St. J., Bloodworth, A. J . , and Morgan, W. J . , Thermochim. Acta, 1985, 93, 741. Tarrer, A. A . , Quin, J. A., Pitts, W. S . , Henchy, J . P., Prather, J . W., and Styles, G. A., in Ellington, R. T., Editor, “Liquid Fuels from Coal,” Academic Press, New York, 1977, p. 45. Cumming, J . W., and McLaughlin, J . , Thermochim Acta, 1982, 57, 3. Balek, V., Thermochim. A m , 1977, 22, 1. de Koranyi, A., and Balek, V., Thermochim. Actu, 1985, 93, 757. Pitt, C. J . , and Milliard, G. R., Editors, “Coal and Modern Coal Processing-An Introduction,” Academic Press, London, 1979. Mikhail, S. A., Thermochim. Acta, 1985, 93, Suppl., 116. Simons, G. A . , “19th Symposium (International) on Combus- tion,” Combustion Institute, 1982, p.1067. Laurendeau, N. M., Prog. Energy Combust. Sci., 1978, 4,221. Smoot, L. D., Prog. Energy Combust. Sci., 1984, 10, 350. Causton, P., and McEnaney, B., Fuel, 1985, 64, 1447. ~~~ A New Approach to Thermal Analysis: Simultaneous Microcalorimetry and Thermogravimetry Measurement; Simultaneous TG - DTA up to 2700K Francis Pithon SETARAM, 7 rue de I‘Oratoire, 69300 Caluire, France Introduction A new range of thermal analysers are now available. They have been generated by long experience and know-how in this field. The main feature of these instruments is a combination of a scanning microcalorimeter with a symmetrical balance and symmetrical simultaneous TG - DTA up to 2700 K. The automation of the sample’s environment (the tempera- Mass-variation monitoring by symmetrical microbalance 1 1 Energy monitoring by heat flux transducer Fig.1. The calorimeter microbalance Sa m p le ” c r uci b I e Reference ” c ru ci bl e heat flux transducers Fig. 2. Apparatus for simultaneous microcalorimetry and thermo- gravimetry ture and the gas) has led to better reproducibility and to the automatic control of complex experimental conditions. Simultaneous Scanning Microcalorimetry and Thermogravimetry: the TG - DSC 111 Calvet microcalorimeters provide a cylindrical space surroun- ded by heat flux transducers, which monitor all the heat transfer, thus giving accurate direct access to the heats of reaction, transformation and the heat capacity. A new design has been developed, in which the sample, instead of standing inside the space, is suspended below a symmetrical micro-ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 - - 13 -400 2 -200 2 - O 3 2 . 0) m r 0 balance (Fig.1). The high performances of both microcal- orimetry and symmetrical microgravimetry are now available simultaneously in a single simple investigation (Fig. 2). This is of great interest, as illustrated by the applications in the field of catalysis, adsorption, oxidation, gas solid reaction, decomposi- tion, pyrolysis dehydration, etc. The importance of the information given by the recording of the mass variation during a DSC scan is illustrated by the oxidation of coal (Fig. 3). The heat flow versus temperature + H20 - - - - - - - - 30 t 0.8 0.7 0.6 TS) 0.5 2 0.4 4 0.3 0.2 5 0.1 7 0 10 c 4 - 5 exo / / 1 2 0 0 1 I I 1 I I I i00 200 300 400 500 600 Temperatu rePC Fig.3. Conditions: 0.932 mg; 10 K min-1; oxygen 0.9 1 h-1 Mass change during a DSC scan for oxidation of coal. graph has two exothermic peaks, and the simultaneous TG curve indicates that the first reaction corresponds to a mass increase, which means that there is chemisorption of oxygen on coal up to 700K. It is followed by a combustion with an important mass loss. Further information can be obtained by analysing the evolved gases, as illustrated in Fig. 4, represent- ing a catalyst investigated under a flow of hydrogen. The evaporation of water, followed by the reduction of the nickel oxide, is monitored through the endothermic and exothermic reactions and the mass variation. During the whole process, the water evolved is measured by means of a mass spectrometer.Evaporation NiO + H2-+ Ni 2 -of adsorbed H20 1 1 1 I I I I I I I Tern peraturePC Fig. 4. Analysis of evolved gases for a catalyst under a flow of hydrogen. Conditions: NiO - Si02 catalyst (3 + 1, rnlm); 10°C rnin-l 80 180 280 380 480 580 680 780 Simultaneous Symmetrical Computer-controlled Thermal Analyser TAG 24 TG and DTA are widely used for quality control and research purposes and the latest developments in TG - DTA equipment, and their practical consequences for the users, are considered below. Symmetrical Design Symmetrical microbalances with a horizontal beam are those with the highest sensitivity. They have excellent long-term stability when the sample is suspended from the beam. The horizontal position is controlled by an opto-electronic system, and the mass changes are adjusted by electro-magnetic compensation.The best TG instruments are founded on this principle, but it is possible to achieve even better stability, better sensitivity and better resolution by having a dual furnace (Fig. 5). In this instance the thermal analyser is fully symmetrical, and it can monitor very small mass variations, down to a few micrograms. Symmetrical balance, very low mass detection Secondary vacuum facility ]lmir-- -- Active gas Symmetrical furnaces, buoyancy compensations #-I---- Simultaneous TG - DTA facility for gas analyser (GC and MS) Fig. 5. TAG 24: T G - DTA. simultaneous and symmetrical The main advantages are the compensation of the buoyancy zffect and the modifications and changes in the gas flow.The difference between a monofurnace (single furnace) and a symmetrical furnace (dual furnace) assembly is measured by a test in which the temperature of both furnaces is scanned, followed, after cooling, by scanning of one of them. The test is performed under a flow of 1 1 h-1 of argon and a heating rate of 1OKmin-1 from room temperature to 1300K. There is no active sample in the crucible and, on both sides of the balance, the same crucible holder is hung with its simultaneous DTA transducer. The two corresponding TG curves are plotted on the same diagram (Fig. 6). The monofurnace curve has a non-linear apparent mass variation of 1.5mg, compared with a few micrograms with the symmetrical dual furnaces. The compen- sation is very good and, with a blank correction, a resolution as low as 1 pg is achieved by means of the symmetrical thermal analyser .I I 1 .o F 5 I- 0.5 0 I I I 1 I I 0 200 400 600 800 TemperatureiOC Fig. 6. T G curves obtained using the TAG 24. T G - DTA configuration: empty crucible: argon at 1 1 h-I; 10°C min-' Simultaneous TG - DTA up to 2700K There is a need for information on the behaviour of materials at high temperature, above 2000K, and only a few instruments could go above this value. The two main reasons that limited the temperature of the thermal analysers to 2000 K were that platinum melts and alumina softens above this value. It is therefore not possible to use these basic materials, which are very reliable, especially as far as the platinum - rhodium thermocouples are concerned. A new instrument, the temperature of which can be scanned up to 2700K, has been developed.It uses graphite furnace technology and the DTA transducers are made of tungsten - rhenium alloy. This simultaneous TG - DTA thermal analyser monitors the behaviour of material at very high temperature. Phase transformation, melting, evaporation and decomposi- tion reactions are investigated. Its high performance is14 /- ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 22 illustrated in two fields of application: high temperature metallurgy (Fig. 7), with the melting of a rhodium sample inside a zirconia crucible; and ceramic research (Fig. S), with the melting of alumina inside a molybdenum crucible. ~ ~~ - - - - - - - I I 1 42 38 34 30 26 22 Temperatu rePC Fig.7. Melting of rhodium in a zirconia crucible Automatic Control of the Sample's Environment The TG and DTA signals can be meaningless if the tempera- ture and the surrounding atmosphere of the sample are not controlled. If this control is important, it is also essential to reproduce it, as this is one of the determining factors in the reproducibility and precision of the technique. It is achieved by use of a microprocessor controller, in which the experimental conditions are kept in memory. They are programmed through a keyboard, the most important ones being the temperature and the gas flow. The temperature of the sample in the system to be investigated is programmed following the requirements of the test. It can be either a simple or a very complex programme.The gas environment is controlled by the proces- sor, which drives eight electromagnetic valves. They allow a wide range of automation of the atmosphere inside the space where the experiment is carried out. Different surrounding conditions can be programmed, such as vacuum, purge, very high vacuum, inert gas and reactive gases at different flow- rates. The fact that the programme is kept in memory provides a high reproducibility of the experimental conditions. Fig. 8. Melting of alumina in a molybdenum crucible Conclusion Thermal analysis has made a great leap forward in recent years, although its basic principles were known many years ago. There are different reasons for this revival, one being the fact that manufacturers have integrated modern technological developments and now provide a new generation of instru- ments which are automated and reliable.Thermal Analysis in Circuits Manufacture C. A. Smith Liquid Crystal Displays, E. E. V. Co. Ltd., Chelmsford, Essex Polymeric materials are increasingly being used in the electron- ics industry. Phenolic and epoxy resins are used in laminates for printed circuit boards, acrylate materials are used as dry film solder resists and photoresists, polytetrafluoroethylene and polystyrene are used as substrates for microwave circuitry and polyimide film is used in flexible circuitry. Thermal analysis techniques are extremely useful for charac- terising these materials, for the determination of kinetic data on polymerisation reactions and for locating phase transitions t I Cure exotherm I Q, Thermal 0 - decomposition sl 1 , I I I I 1 I" 50 100 150 200 250 300 Temperatu re/"C Fig.1. DSC curve of a B-stage epoxy glass prepreg 4 l T ,/-\ Standard prepreg I I , I I I 50 100 150 200 250 300 Tern peratu re/"C Fig. 2. DSC curves of standard and no-flow epoxy glass prepregs such as the glass transition in amorphous polymers. The techniques used include differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Epoxy Glass Prepreg Prepregs are pre-engineered laminating materials used in the manufacture of fibre-reinforced composites. 1 Those used in multi-layer printed circuit board manufacture, where they act both as an insulating layer and a bonding material between the inner layers that carry the circuitry, consist of a glass cloth pre-impregnated with a B-stage epoxy resin.This is a partially cured, vitrified resin requiring only heat to cure fully. B-stagingANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 + 15 is carried out to provide a material that is easy to handle and simple to process. The degree of B-stage cure is determined using DSC, from the glass transition temperature or from the enthalpy of reaction of the uncured resin when it is heated. To make a measurement, the epoxy resin is first removed from the glass cloth and a weighed amount (20 mg) is placed in an aluminium pan. This is sealed and placed in the calorimeter alongside an empty reference pan. The sample is heated at 10"Cmin-1 to 300 "C and this gives the curve shown in Fig. 1 ~ which is a plot of heat flow against temperature.The resin first undergoes a glass transition which appears as an endothermic peak at 60°C. This may be used to determine the degree of cure, as the temperature of this transition will increase with the degree of cure. The actual curing reactipn starts at 100°C and is denoted by a small exothermic rise followed by the main exotherm, which reaches a maximum at 160°C . It is the enthalpy, A H . of this reaction that has been used by Smith'J to characterise prepregs for use in multi-layer printed circuit board manufacture. AH can be used as a measure of the degree of cure as the heat of reaction decreases with a decrease in the amount of uncured resin left. AH is inversely proportional to the degree of cure. It is also related to the amount of flow achievable in the laminating press.Prepregs with A H 3 100 Jg-1 are preferred. These have good flow properties and always result in successful lamina- tion. Prepregs with AH < 100 J g-1 do not flow easily when heated and this results in delamination, which appears as air pockets within the printed circuit board. AH is used as an incoming goods quality control test on all batches of prepreg. In the case of one major supplier, AH correlates very well with their own test based on the scaled flow method developed by Bell Laboratories and Western Electric in the USA.4 In this test prepreg is characterised (scaled) by its flow in a small test press, which is related to the thickness of the cured composite. The higher the scaled flow number, the higher the flow and A H .corresponding to a lower degree of B-staging (cure). Other tests for epoxy - glass prepreg used in multi-layer printed circuit manufacture have been reviewed by Schiffers and Carreman.6 t r I I transition decomposition I Another example concerns no-flow epoxy prepreg, used in the manufacture of flexi-rigid multi-layer circuits, to laminate polyimide film and epoxy glass laminate together. In this instance a flow inhibitor has been added to the resin to reduce the amount of flow when it is heated. This also results in the epoxy becoming less brittle. The DSC curve is slightly different (Fig. 2) and the heat of reaction is lower. The experimental procedure for determining AH is the same as that used for standard prepregs except that the sample must be corrected for the glass cloth, which is not easily separated from the resin.The test is also run in a nitrogen atmosphere to reduce drifting of the DSC curve. The temperature and the time required to laminate epoxy glass laminate to polyimide film using no-flow prepreg is extremely critical. If the resin is not fully cured, de-smearing the holes in the printed circuit board using chromic acid after drilling will result in etch back along the bonding layer. Over-curing results in decomposition of the resin and delami- nation of the circuit board. Samples of no-flow prepreg were bonded to polyimide film and cured in a lamination press at temperatures ranging from 110 to 205 "C for 1 h. The degree of cure was then determined from the enthalpy of reaction of uncured resin using DSC.AH was found to decrease with increasing lamination temperature up to 170°C. This was confirmed by measurement of the glass transition temperature which reaches a maximum at 170 "C. Laminating for 1 h at 170 "C cures the no-flow prepreg resin to a level comparable to the degree of cure in the epoxy glass laminate, without decomposing the epoxy resin. Part of the problem is that even when fully cured the glass transition temperature of no-flow prepreg is 20°C lower than that of cured epoxy glass laminate and standard prepreg. This results in disproportionate etching during the de-smearing process. Epoxy Glass Laminate A second group of materials used in printed circuit manufac- ture are the base laminates. Phenolic - paper composites have been used for some time, but modern high-quality circuits for military and aerospace applications use epoxy glass laminates.Methods for characterising laminates have included measure- ment of the decomposition temperature using TMA and TGA and measurement of the glass transition temperature using TMA and DSC.7 0.15 t t c 0 v) C m X .- a 5 0, a J I I I I 50 100 150 200 Temperatu re/"C Fig. 4. TMA curve of an epoxy glass laminate To determine the glass transition and thermal decomposition temperatures by DSC, a small section of laminate is placed in an aluminium pan in the calorimeter alongside an empty reference pan and heated at 10 "C min-1 to 300 "C. This gives the DSC curve shown in Fig. 3. The glass transition temperat- ure for a fully cured epoxy glass laminate is 130 "C, and appears as a discontinuity in the heat capacity.The decomposition temperature appears as an exothermic rise at 2200°C. Both values are dependent on the degree of cure. Exothermic peaks at 160 "C indicate residual chemical reaction owing to incom- plete cross-linking of the epoxy resin. Glass transitions, blistering, delamination and decomposi- tion can all be determined by TMA. In TMA the expansion of the resin is measured under an applied load as the temperature is raised with time. The result is a plot of expansion against temperature. Samples are annealed beforehand to relieve stress present in the polymer, using an accelerated heat-up rate, to a temperature below the decomposition temperature. The actual test is made at a heating rate of 10"Cmin-1 to 300 "C.A typical TMA plot for a glass epoxy laminate is shown in Fig. 4. At the glass transition temperature the rate of expansion changes, and this is shown as a step in a plot of the16 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 I 1 I 1 I 1 0 100 200 300 400 Tern Deratu re/"C Fig. 5. mask Change in enthalpy with degree of curve for dry film solder first derivative of expansion against temperature. Blistering, delamination and decomposition are all shown as rapid increases in expansion. Solder Mask Two types of solder mask are in common use in the printed circuit industry. Dry film solder mask is a photopolymeric coating, often based on an acrylate polymer, which is applied as a film to the printed circuit board after manufacture to prevent solder bridging between conductors when components are wave soldered into place.The polymer is photoimaged and cured by photochemical free radical reactions that are initiated by exposure to ultraviolet light. However, heating in a conveyorised oven and further exposure to ultraviolet light is often necessary to cure the polymer fully. Infrared heating may be used. 1 1 I I I I I I I 50 100 150 200 250 300 Tern peraturei'c Fig. 6. DSC curve of a screen printable liquid epoxy solder mask Liquid epoxy solder masks are also used and these are applied to the printed circuit board by screen printing. The pattern is produced using a stencil. They have the advantage that they are much cheaper and only require heating at 120 "C for 30 min-1 h in an oven to cure fully.They do, however, lack the definition that can be achieved using dry film solder masks. Recent advances in polymer chemistry have led to the development of screen printable solder masks that can be photoimaged and cured using ultraviolet radiation. This gives the definition of dry film solder mask, without the cost. DSC curves of dry film solder mask are shown in Fig. 5 , in which the enthalpy of the major peak is an indication of the degree of cure. The same principles used to determine the degree of cure for epoxy resin prepregs can be used here. Any trace of an exotherm on the DSC curve is evidence that the processing conditions are not curing the solder mask correctly. Fig. 6 shows a DSC curve of a screen printable liquid epoxy solder mask. I I I 1 I 100 200 300 400 Tern peratu re/"C Fig.7. DSC curves of dry film acrylate solder masks DSC curves may also be used to differentiate between similar solder masks. Fig. 7 shows two dry film solder masks, one of which has an endothermic peak at 150 "C, indicating an additive not present in the other material. Both solder masks have cure exotherms near 240"C, showing them to be chemically similar. References 1 . 2. 3. 4. 5. 6. 7. Molyneux, M., Composites, 1983, 14, No. 2, 87. Smith, C. A . , Circuit World, 1985, 12, No. 1, 29. Smith, C. A., GECJ. Res., 1985, 3, 162. Bloechle, D. P., Circuit World, 1982, 9, No. 1, 8. Schiffer, W., Circuit World, 1986, 12, No. 3, 4. Carreman, J., Circuit World, 1985, 11, No. 4, 32. Smith, C. A . , Circuit World, 1986, 12, No. 2, 62. Quantitative Differential Scanning Calorimetry-from Heat Capacities to Free Energies M.J. Richardson National Physical Laboratory, Teddington, Middlesex TWI I OL W When the Thermal Methods Group was founded in 1965, thermodynamic standards for the subsequent application of calorimetry was a specialised technique practised in only a few differential scanning calorimetry (DSC) to more conventional laboratories throughout the world. Because of sample require- materials, potentially transforming the calorimetric scene, ments, operational complexities and the time scale of days, or "Potentially" must be emphasised because the majority of even weeks, measurements tended to be made on very well reported applications of DSC use it only as a fairly crude defined, highly purified materials rather than those which were characterisation technique that does not utilise the full met in day to day usage.The former should have provided the potential of the several instruments that are now availableANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 c 30 I Y cs, >. 0 r I 2 t. .- g 2 0 - m V m a c I 10 17 - - commercially. This was understandable before microcomput- ers became widespread: successful quantitative operation requires much simple, but tedious, mathematics and computa- tional aid is essential, but with this, any routine measurement is readily transformed into one of thermodynamic significance. This paper will briefly review the steps needed to produce free energy curves. Calibration: Temperature Quantitative work is possible only if both ordinate and abscissa are correctly calibrated.The latter is a time or, more usefully for the scanning mode, a temperature which may be directly measured or derived from the known heating or cooling rate. Whatever procedure is used, the final value refers to a sensor that is not in direct contact with the sample so that there is thermal lag between the two. The conventional temperature calibration seeks to overcome this by calibration with materials of known melting (or transition) temperature at the relevant heating rate (commonly 10 or 20 K min-1). This gives a unique calibration graph that clearly cannot be valid for all materials or even for different masses and/or geometries of the same material. This difficulty can be overcome by using the “enthalpy lag” (when the final programmed temperature is reached) to generate a thermal lag for individual runs.This procedure has the great advantage of being valid for cooling as well as heating-because of supercooling, conventional calib- rants do not freeze at well defined temperatures. Calibration: Specific Heat The ordinate is a differential power or temperature in power-compensation or heat-flux DSC, respectively. In both instances the magnitude is proportional to the difference in “heat capacity” between the sample and reference cells. “Heat capacity” includes all processes demanding or generating energy so that, in addition to the heat capacity itself, there may be heats of fusion or transition, recrystallisation and annealing 40 t T, 373.0 340 360 380 Tern pe ra t u re!K Fig.1. biphenyl (2.OCB). Heating rate, 10 K min--’ Heat capacity of solution-grown crystals of 4.4’-ethoxycyano- phenomena and chemical reactions. These processes super- impose peaks or troughs on a normally monotonous heat capacity curve and special treatment may be required for local disruptions to pseudo steady-state conditions. Fortunately, a common calibration is generally adequate, whatever the sample behaviour. Subtraction of data for the empty pan from that of the pan + calibrant (mass m,, specific heat cpc) gives the calibrant signal S, and KS, = rnccpc where K is the ordinate to heat capacity conversion factor. The most widely used calib- rant is a-alumina, although benzoic acid is useful at low temperatures. Once K has been established the procedure is reversed and cps (subscript s = sample) becomes the unknown.K is not normally recorded as such because cps = (m,c,,S,)/ (m,S,) - KS,/m, and the whole calculation is normally carried out in one operation. However, the behaviour of K is a useful indication of instrumental performance-how it is affected by instrumental settings and temperature (both ambient and programmed) and, for a given set of conditions, its day to day reproducibility. A variant of the above procedure is to measure an urea that corresponds to a known enthalpy change. Heats of fusion are popular candidates for this procedure, but an area due to heat capacity effects alone is equally valid. Whatever quantity is chosen, great care must be taken to ensure that the area measured corresponds to a thermodynamically meaningful quantity.Most “base lines” that are described in the literature do not meet this condition. Specific Heat and Enthalpy Changes A modern DSC gives heat capacities (cp) (Fig. 1) that are accurate to kl% over most of the temperature range of the 0 r I 0 -100 2 - 0 m 0 - 5 -200 P - 300 I I 1 I 320 340 360 380 Tern peratu re/ K Fig. 2. Enthalpy changes calculated from Fig. 1 using H , (390 K) as the reference state; the monotropic liquid crystal phase is also shown. _ _ -, Idealised curve; - - - -, liquid extrapolated assuming cp, = a + bT instrument. Integration leads, in turn, to enthalpy - tempera- ture curves (Fig. 2) which, whenever possible, should always be referred to a reproducible and well defined state-in Fig. 2 this is the isotropic liquid at 390 K.Heats of fusion [AH( r>] follow after extrapolation of data for the liquid; for molten 2.OCB this is mathematically simple because a linear cp - T relation- ship holds. A similar form of equation is valid for the solid, and the broken lines in Fig. 2 show how an idealised H - T curve I I A T X X k T- Fig. 3. Detail for the calculation of entropy changes (see text)18 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 would appear for 2.OCB in the absence of pre-melting and instrumental rate effects. In a correctly calibrated DSC the only effect of changes in the heating rate should be an apparent displacement of the enthalpy step, the magnitude at T, remaining unchanged. “Apparent” displacement should be emphasised because the effect is not due to superheating, as might be inferred from Fig.2, but to the finite time needed to transfer heat of fusion to the sample. Although it is not difficult to obtain AH( T,) from Fig. 2, entropy changes need some care in their derivation and this is considered below. Entropy Changes The formal calculation of entropy (S) changes from heat capacity data is by summation of terms in c,AT/T, (Fig. 3). This procedure is only valid in regions of thermodynamic reversibility where results should be independent of both the sign and magnitude of the rate of change of temperature (compliance with this requirement is a good test of the over-all performance of a DSC). When the reversibility criterion is not met, as in regions of melting or, especially, crystallisation (supercooling often delays this by tens of degrees), the apparent entropy change may decrease (melting) or increase (crystallisation) with increase in rate of change of temperature.The true, reversible entropy change must be somewhere in between and a good approximation may be obtained by extrapolating heating data to zero rate. However, this proce- dure loses the convenience of rapid experimentation and a satisfactory compromise is to calculate the entropy change along the idealised (broken) curves of Fig. 2 using standard thermodynamic procedures. Additional, low-temperature phase changes can be similarly treated. It is very useful to list both this calculated (reversible) entropy change and the observed (irreversible) value so that the correction to the latter can be monitored as a function of sample size, heating rate, etc. Pre-melting effects are neglected in this calculation but they are usually very small compared with the over-all value. Temperature + Fig. 4. the definition of AG( T ) Schematic free energy curves for the 2.OCB system showing Entropies of fusion [AS( 7‘)J are obtained by extrapolation of data for the molten material just as for AH(T) (Fig. 2). The reversibility correction can increase AS by up to 1% for a 10 K min-1 heating rate but the correction for supercooling can be an order of magnitude larger. Free Energy Changes Previous sections have shown how DSC measurements are used to derive AH(7‘) and AS(7‘). The corresponding Gibbs free energy follows from AG( 7’) = GI( 7‘) - G,( 7‘) = AH( 7‘) - TAS(T), and Fig. 4 demonstrates how GI functions as the reference state. The full curve in Fig. 5 shows AG( 7‘) for the solution-grown crystals of 2.OCB to which the data of Figs. 1 and 2 refer; here T, = 373.0 K and AH(373.0) = 117.6 J g-1. A different structure, with T , = 375.4K and AH(375.4) = 100.6 J g-1, is obtained by crystallisation from the melt in the DSC. This phase (broken line, Fig. 5 ) becomes metastable below 360.OK, accounting for the very slow transition to the solution crystallised form that is observed at room tempera- ture-many months are required for completion. Cyanobi- phenyls are particularly important for their liquid crystalline behaviour, 2.OCB is monotropic, the nematic - isotropic liquid transition [T, = 363.0K, AH(363.0) = 4.1 J g-I] is only observed in the supercooled liquid because the nematic phase is metastable with respect to either of the solid forms (Fig. 5 ) . 20 0, 7 - 10 I- U 4 - Nematic 0 TemperatureiK Fig. 5 . AG(T) for the several forms of 2.OCB Polymorphism is an extremely widespread phenomenon. Thermodynamics indicates nothing about the kinetics of phase changes but the information that it gives about their absolute stabilities is of great importance when properties are in- fluenced by crystal structure, the solubility of a drug, for example. DSC gives the required information with only minimal, soundly based assumptions.

ISSN:0144-557X    

DOI:10.1039/AP9882500008

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 19 Particles in Hot Gases-Sampling and Sample Preparation The following are summaries of two of the papers presented at a Meeting of the Particle Characterisation Group, held on June loth, 1987, at the Health and Safety Executive, 403-405 Edgware Road, Cricklewood, London N.W.2. Smoke Particles and their Optical Properties 1. Colbeck Institute of Aerosol Science, University of Essex, Wivenhoe Park, Colchester C04 3SQ Smoke is typically a heterogeneous mixture of particles of different sizes, structures and composition. High-temperature, flaming combustion produces black sooty smoke whereas white, oily smoke is formed by low-temperature, smouldering combustion. The environmental effects of smoke in the atmosphere. such as visibility reduction, air pollution and the so-called Nuclear Winter are predominantly caused by sooty smoke.Although their mass concentration is small compared with other particles in the atmosphere, these smoke aerosols have the unusual property of strongly absorbing light of visible wavelengths, but transmitting light of infrared wavelengths. This behaviour is central to the alteration of climate but the exact properties vary according to the origins of the particular smoke. Optical Properties The optical properties of smoke are functions of chemical composition, morphology and particle size. The composition depends on the type of fuel and the conditions under which it is burnt. The morphology and size are determined by formation processes and subsequent microphysical processes (e.g., coagulation and absorption of water vapour).As the physical properties of the particles are changing with time, the optical properties also change with time. 2.0 1.5 . 5 % $ 1.0 .- v) + Y 0 - 0.5 0 / / / r( / / / / 2000 1000 z 500 i 64 I I I I ‘/4 1 4 16 Ageing ti me/ h 0.3 0.25 E ‘1- 0.2 0.1 Fig. 1. Variation in morphology of carbonaceous smoke with ageing time, determined from SEM investigations. V , is the equivalent volume radius It has been traditional to use the Mie theory for homogeneous spheres to calculate the optical coefficients of atmospheric particles. This enables the variation of absorption with particle size to be modelled, assuming that they are spherical. It suggests that the extinction should decrease linearly with the size of the spherical aggregate, beyond a radius comparable to the wavelength.However, the shape of smoke particles can be fairly complex. Laboratory studies of black sooty smoke have shown it to be in the form of branched-chain agglomerates composed of smaller spherules. These fluffy clusters of spherules are up to 20ym in total length, whereas the individual particles are all of roughly equal size, about 2G.50 nm in diameter. Previous workers have con- verted the measurements of agglomerate size to an equivalent Scattering angle 4 Detector Laser I n Diffuser - detector Fig. 2. Schematic diagram of experimental layout volume diameter and then used the Mie theory. Recently, Berry and Percivall have developed a theory for light scattering from fluffy particles, based on the assumption that they consist of fractal aggregates of spherules, each spherule being signifi- cantly smaller than the wavelength of light.For a cluster containing Nparticles all of radius a, the cluster size, R , is given by R = aNl’D where D is the fractal dimension. If D = 1, then the spherules are formed into straight lines, if D = 2 they are in sheets and if D = 3, they are in a solid spherical shape, as assumed by the Mie theory. Computer models and measure- ments have shown the smoke clusters to have a fractal dimension of 1.78. Fractal theory predicts that when smoke coagulates in clusters of D < 2 the absorption of light is hardly changed and that the scattering per spherule initially increases and then levels off at a value exceeding that of an isolated spherule.20 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Experimental Experiments have been performed to study the influence of particle shape and morphology, as a function of time, on light scattering and absorption.Smoke produced from the combustion of liquefied petroleum gas has been sampled on 0.4 pm nuclepore filters and examined by scanning electron microscopy (SEM). From the SEM micrographs, the projected area of the cluster, fractal dimension and individual particle size have been estimated. Hence, the cluster size and number of particles in a cluster can be calculated. Their variation with time is shown in Fig. 1. It can be seen that after 16 h the cluster size has increased four-fold, whereas the number of particles in a cluster has increased approximately 20 times. A transmissiometer and integrating nephelometer have been designed to study the effect of coagulation on the optical properties (Fig.2). Observations of the molar absorption coefficient, by measuring the direct beam obscuration, appear to show that it remains remarkably constant with time with a value of approximately 1 1 m2 g-1. Similarly, the single scatter- ing albedo shows no significant trend. Hence, it appears that aggregation does not influence the optical properties. The polar nephelometry indicates the predominance of forward scatter and little change in the asymmetry factor with time. These observations are consistent with the optical theory of fractal smoke, and suggest that the absorption of light by smoke is hardly affected by coagulation.Reference 1. Berry, M. V., and Percival, I. C., Optica Acta, 1986, 33, 577. Particles and Sampling from Flames and Flue Gases A. M. Godridge Central Electricity Generating Board, Technology Planning and Research Division, March wood Engineering Laboratories, Marchwood, Southampton SO4 4ZB The studies described here are concerned with methods for sampling particles from flames, where temperatures are around 15OO0C, and from flue gases at the back end of boiler plants where temperatures are likely to be lower (12G3OO"C). In the boiler furnace, carbon burn-out data are required for flame models and heat transfer calculations. At the economiser and after the precipitators, particle concentrations are measured in order to assess precipitator efficiency and the amount and composition of particles going to the chimney.Combustion equipment that uses'gas or light oil as a fuel will, under certain conditions, make smoke. The fine soot particles present, which are made up of carbon with a little hydrogen, will individually be about 0.05 pm in size, although they may form long chains. Where heavy fuel oil is burnt and particularly residual fuel oil (RFO) soot, oil-coke particles and a little ash may be present in the emissions. The coke particles will be mainly in the size range 10-100pm. RFO contains only up to about 0.05% ash so that it is the coke and soot that makes up the bulk of the emissions. For coal-fired boilers, where the ash content of the coal can be up to about 3570, the main concern is with ash particles, although soot and coal chars or cokes may be present.Much of the ash (2040%) falls to the boiler floor and can be removed but the remainder, apart from deposited material, eventually reaches the boiler exit. Here it can be trapped in cyclones or electrostatic precipitators and only a very small amount (<0.115 grams per normal cubic metre at present) goes on to the chimney. Soot Measurements In the Shell method used here, a stain is produced by drawing the flue gases at a constant differential pressure through a filter-paper. The filter-paper, the differential pressure and the sampling time have been standardised as Whatman No. 4 , 3 in Hg (101.6 mbar) and 1 min, respectively. Comparison of the stain with a standard range of shades varying from white to black then yields a Shell smoke number between 0 and 9.This progression from white to black is in equal photometric steps through neutral shades of grey. The smoke scale spot number is defined as the percentage reduction, due to the smoke stain, of reflected incident light divided by ten. Thus, the first spot, which is the colour of the unprinted scale, is zero as there is no reduction in reflected incident light. The last spot on the scale is very dark and reflects only 10% of the incident light, corresponding to a reduction of 90% and hence a smoke number of nine. Smoke numbers can be measured by comparison with a printed scale and also by using a reflectometer, the instrument being set to represent 100% reflectance from a clean filter- paper. In flames, a water-cooled probe with the filter-paper mounted at the inlet end can be used.Matthews et al.1 have described such a probe for use in natural gas flames. The probe is essentially in two parts: a If in (38.1 mm) 0.d. water jacket and a 5/16 in (7.9 mm) 0.d. sampling tube which fits inside the water jacket and carries the filter-paper. The axial position of the sampling tube in the water jacket can be varied in order to control the temperature of the gases at the filter-paper. Graphs relating carbon concentration to smoke number are reported. There are a number of continuous automatic smoke density meters on the market using a lamp on one side of the duct and a photoelectric cell on the other. These instruments need to be accurately aligned optically and can be difficult to check for electrical component drift and clean optics.Instruments operating from one side of the duct only have been developed and these can be more easily removed or checked and are not affected by duct distortion. These developments have been summarised.2 Coke and Ash Measurements Measurements in Flue Gases No single instrument will give an automatic indication of the total solids burden in the flue gases. Instruments that are available respond either to small or large particles. The former give the plume its visibility so that they can be measured optically with smoke density meters, but the latter, contribut- ing to ground level deposits, need to be caught before their concentration can be determined. For measuring the larger particles in the flue gas a semi-continuous permanently installed instrument, called the CERL flue dust monitor, has been described by Snowshill.3 Here the instrument collects a solids sample by deposition on glass plates mounted in a specially designed cell.Their optical observation is integrated over an interval of some minutes before an air purge re-establishes the zero condition.ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 21 In order to collect samples of solids in the flue gas ducts of oil-fired boilers, where the solids concentrations are low, it is usual to use probes with filters (usually silica wool or tyglass bags-i. e . , woven glass fibres-although more recently PTFE filters have been used). The filters may be located at the hot end of the probe in the plant, or at the cold end outside the plant.In the latter instance the filter will need to be kept at a temperature above the acid dew point. Three types of probe have been tested, two with filters at the hot end of the probe and one with the filter outside the boiler. The concentrations and size distributions of the material collected were the same in all instances. On coal-fired plants these filters, with the possible exception of the bags, would block rapidly and miniature cyclones have been used ahead of the filters, e . g . , reference 4. Again, the cyclones and filters can be inside or outside the flue gas duct. Sampling in Flames In flames where the temperatures are much greater than the flue gas (1500°C compared with, say 300°C) it is necessary to use water-cooled probes.In oil-fired flames the filter can be located at the hot end, because the filter will block only slowly, and manually operated probes for doing this have been described5 where the filter is made of sintered bronze. However, this type of probe needs to be pulled in and out of the flame each time a sample is taken. It is more convenient to bring the sample to the back end of an internally heated probe (to prevent condensation and the solids sticking in the sample line). This is particularly true in coal flames, because it is usual to use cyclones to collect the solid material, and these cannot be located in the flames. It is possible to use a resistance-heated tube inside a water-cooled probe.6 This arrangement is complicated, but very necessary to avoid condensation and the formation of sludge in the probe.Another method that we have used involves cooling the probe with oil, operating at between 150 and 200 “C. In this way the dust-laden gases coming into contact with the probe walls will find surfaces at temperatures above the dew point. The cooling oil used is Transcal SA, manufactured by BP. The oil is capable of operating at bulk fluid temperatures of 320-343 “C and a skin temperature of 370°C. The vapour pressure is low (0.04 bar at 200°C) and the oil presents no special handling problems. The probe is fitted with thermocouples for monitor- ing the metal wall temperature and the bulk fluid temperature. The oil is circulated through a cooling circuit which comprises a water-cooled heat exchanger, pump, flow meter, expansion tank and valves. Particulate Material The soot - coke mixtures obtained from heavy fuel oils contained up to 8% hydrogen.The other non-carbonaceous material in these mixtures was ash and this ranged from about 14 to 36%. This ash contained many of the constituents present in the original oil; for example, V (27.6), Ni ( 5 . 8 ) , Fe (4.2), Ca (4.2), A1 (3.6), Na (15.2), Si (13.6), S (25.6), where the values refer to the percentage of oxide present. Most of the material, by mass, was in the size range 10-100 pm. Of course, this will depend very much on the quality of the initial fuel-oil atomisation. Particles from coal-fired plants contained different minerals from those present in oil, for example, more silica, aluminium, iron and calcium. A detailed comparison has been made of the impurities in oil and coal.’ Before the precipitators in a coal-fired plant the particles sizes are similar to those from an oil-fired plant (but of a different composition with only about 5% carbon), being up to about 100pm in size. After the precipitators or at the chimney, sizes are up to only about 20 pm.8 The work was carried out at the Marchwood Engineering Laboratories of the Technology Planning and Research Divi- sion and the paper is published with permission of the Central Electricity Generating Board. 1. 2. 3. 4. 5. 6. 7. 8. References Matthews, K. J . , Parr, M. K., and Stern, G. R . , J. Inst. Fuel, 1969, 42, 275. Richards, D. J. W., Jones, W. S., and Laxton, J . W., CEGB Res., 1977, 5 , 18. Snowshill, W. L., Anal. Proc., 1981, 18, 528. Hawksley, P. G. W . , Badzioch, S . , and Blackett, J. H . , “Measurements of Solids in Flue Gases,” BCURA Leather- head, 1961. Chedaille, J., and Braud, Y., “Industrial Flames,” Volume 1, Edward Arnold, London, 1972. Cowan, C. E., “A Combustion Solids Sampling Probe,” CEGB Report RD/M/M64, Unrestricted, CEGB, Southampton, 1969. Hart, A. B., and Lawn, C. J., CEGB Res., 1977, 5 , 4. Raask, E . , “Mineral Impurities in Coal Combustion,” Springer- Verlag, Berlin, 1985.

ISSN:0144-557X    

DOI:10.1039/AP9882500019

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

22 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Equipment News X-ray Fluorescence Spectrometer The QX is a wavelength-dispersive instru- ment which can be fitted with up to 10 monochromators for the simultaneous determination of up to 10 elements. The element range is sodium to uranium, and each instrument offers the choice of vac- uum or helium atmosphere. Controlled by the IBM PC System 2, the QX has a number of dedicated application pack- ages (e.g., cement analysis) available. Oxford Analytical Instruments Ltd., 20 Nuffield Way, Abingdon, Oxfordshire OX14 1TX. Software for Spectroscopy Further versions of Spectrafile infrared and ultraviolet software are announced so that most currently available spectromet- ers are now able to be interfaced. The latest release includes new spectrometers from Perkin-Elmer, Hitachi, Shimadzu, Kontron and Pye Unicam.Also announ- ced is a new analog interface, which allows users of Pye Unicam SP3 spec- trometers to interface directly with Spec- trafile without using the more costly RS232 interface. The new interface sup- ports scanning and re-plotting of spectra together with limited range scans, a “go- to” function and slewing of the monochro- mator. A new multi-component analysis routine allows the simultaneous quantifi- cation of up to 10 components in a complex mixture. For routine work, Cali- bration curve generation is allowed with up to nine standards possible. Heyden and Son Ltd., Spectrum House, Hillview Gardens, London NW4 2JQ. Software for Spectrometry LAB40 is a data processing software option consisting of four modules: for computer - computer transmission, custo- mised reporting, quality control and cost optimised charge correction.Intended for use with the makers’ range of X-ray and optical emission spectrometers, it enables the output of stand-alone instruments to be presented in various application- or user-specificformats. Moreover, the trans- mission facility allows the transfer of data to a remote computer for operations such as archiving, management reporting and financial administration. Another new addition is a version of the X40 analytical package for the makers’ P3100 Series personal computers and other IBM-com- patibles using the MS DOS operating system. Suitable for both PW1404 sequential and PW1606 simultaneous spectrometers, it incorporates all of the features previously available for DEC- based installations; in particular, it per- mits the use of the makers’ theoretical “alphas” for matrix correction.Philips Industrial and Electro-acoustic Systems Division, P.O. Box 218, 5600 MD Eindhoven, The Netherlands. X-ray Detector Psi is a thermoelectrically cooled X-ray detector which requires no liquid nitrogen cooling; it can be used in several materials analysis techniques. The elimination of liquid nitrogen cooling means reduced size, weight and cost, with increased convenience, a wider range of applicabil- ity and more mobility for many types of analytical instruments. Psi captures the entire spectrum of energies from X-ray diffraction, scatter and fluorescence information at every Bragg angle.The analyser electronics can then select the wanted and reject the unwanted spectral window regions for reprocessing. Kevex Corporation, 1101 Chess Drive, Foster City, California 94404-1199, USA. Atomic Absorption Spectrometer The Model 2100 is a fully IBM PC controlled instrument. It can determine up to 18 elements in 50 samples with fast throughput. Automatic lamp turret, burner positioning, gas box and flame sensing are standard features. By using the makers’ quick change mount the user can change from flame to furnace opera- tion in less than 3 min. A new furnace and autosampler are also available. The Model HGA700 is designed to be inter- faced directly to either the Model 2100 or the Model 1100B. Rapid graphite furnace signals are fully resolved on the high resolution display screen of the Epson PC or IBM PC controller.Background cor- rected analyte signals (solid line) and background-only signals (dashed line) are shown simultaneously to provide com- plete analytical information. The AS70 is the furnace autosampler; it offers simpli- fied programming from the spectrometer keyboard, automatic set-up of all auto- sampler parameters from stored methods, automatic calibration with improved accuracy with multiple standards, and variable pipetting speeds for handling viscous samples. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Accessory and Software for Colour Analysis A large aperture integrating sphere acces- sory has been specifically designed for colour measurement (diameter 150 mm).Its large aperture minimises small variations in the sample surface. Moreover, it offers good sample accessi- bility and is easily removed to enable the instrument to be used for transmission and absorbance measurements. COLOR- 2, a new version of the existing colour software, features CIE and laboratory measurements on both live and stored data using 2 observer positions and 3 illuminants, colour difference, whiteness/ yellowness index, recalculation of LAB and LUV values, interaction with PECUV software data files, and trans- mission measurements. A version of this software for the 7000 Series Professional Computer is also available (COLOR-3). Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Software for Emission Spectrometers ES30 is an analytical software package for the makers’ PV8030 and PV8050 Series optical emission spectrometers. It permits system calibration, automated analysis and results calculation via the makers’ P3102 or other IBM PC-compatible com- puter.Calculation facilities include a choice of mathematical models for inten- sity-concentration conversion plus regres- sion analysis to ensure reliable calibration over wide concentration ranges. Accu- racy is further enhanced by the use of additive and multiplicative intensity car- , rections for matrix effects, which are again derived by regression. Philips Industrial and Electro-acoustic Systems Division, P.O. Box 218, 5600 MD Eindhoven, The Netherlands. Data Handling Package for Chromatography Version 2 of Chromatochart contains significant enhancements, including higher resolution graphics, which make full use of the IBM Enhanced Graphics Adaptor.Another new feature is batch reprocessing of chromatograms, which further increases the speed at which data can be processed. Heyden and Son Ltd., Spectrum House, Hillview Gardens, London NW4 2JQ.ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 23 Dedicated Gas Analysis Carlo Erba Instruments have developed a series of dedicated gas analysers based on the existing Mega and Vega Series of gas chromatographs. The system employed provides a user-friendly analyser which may use TCD and FID in series, 2 TCDs and an FID, or TCD, methaniser and FID in series. Systems have already been developed for natural gas (IS0 NORM 6974), natural gas (modified), trans- former oil gas analysis (TOGA), hydro- carbon gas analysis using a wide-bore capillary and hydrocarbon gas analysis using a narrow-bore capillary.Carlo Erba Instruments (UK), MSE, Sussex Manor Park, Gatwick Road, Crawley RH10 2QQ. Chromatography Works tat ion Each Turbochrom multi-channel, multi- tasking, chromatography data station is able to acquire, process and reduce data from up to 15 instruments simultaneously. It can. at the same time, be used to generate custom reports, optimise acqui- sition parameters and run other pro- grams. It runs under MS DOS and uses Microsoft Corporation’s new Windows operating environment. The latter is a visual interface which allows the concur- rent operation of several programs or activities on the same CRT screen.User interaction with Turbochrom is by means of a mouse. Turbochrom is compatible with the new IBM Personal Systemi2 series of computers. For users of the makers’ Model 2600 there is a package available which upgrades the software to the new Model 2700 (Turbochrom) chromatography data system. Nelson Analytical Ltd., 860 Birch- wood Boulevard. Warrington, Cheshire WA3 7QZ. HPLC System The Model 510 isocratic HPLC system, ideal for instructional use, features a rapid refill pump and pulse damper for smooth flow, 3XL injector, which allows easy selection of three different internal sam- ple loops, settable highilow pressure shut- offs for sample protection, and a prime/ purge valve for easy mobile phase change. Options include semi-prep pumpheads, semi-prep flow cells and wavelength selection filters.Scientific Glass Engineering (UK) Ltd., 1 Potters Lane, Kiln Farm, Milton Keynes MKll 3LA. Detector for HPLC The LC-235 is a diode-array detector, which features automatic peak purity assessment, automatic identification of the wavelength of maximum absorbance, programmed and on-demand collection of spectra, high sensitivity spectra with spectral overlay, biocompatibility and double-beam diode-array optics monitor- ing of both sample and reference. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Instrumentation and Software for Thin-layer Chromatography A new analyser and evaluation system package, Berta + Eva, turn 2-dimen- sional TLC into a viable analytical tech- nique. Fifty times faster than sequential pseudo-2D imaging, Berta measures the whole surface of a 20 x 20 cm plate and gives good resolution in both dimensions, better than 1 mm in the case of CI4.The Eva evaluation system displays chromato- grams on a screen as a graph or colour- coded contour map. Regions of interest can be defined with a mouse for closer examination. Also available is a 2-D ploti2-D integration program, which runs on the makers’ Rita TLC analyser. This program is intended to plug the gap between Rita used in the conventional way and Berta + Eva. Raytest Instruments Ltd., St. John’s House, 131 Psalter Lane, Sheffield s11 8UX. Software for Gel Permeation Chromatography GPC 2000 is a software package for graphical and numerical analysis on data derived from GPC. It is designed as an enhancement package for the makers’ chromatography laboratory automation system (CLAS).The output from GPC 2000 includes a GPC calibration curve, a GPC data report, including sample reten- tion time and various molecular weight statistics, and graphical presentation of weight molecular weight, number mol- ecular weight and percentage cumulative weight molecular weight. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Automatic Coulometric Karl Fischer Titrator The AF7 has been developed to offer rapid analysis. It is capable of titrating water at 20 mg min-1, which equates to coulometric titrations with the speed and moisture range of titrimetric instruments. Moisture measurements over the range 1 p.p.m.-100% water are attainable on one instrument.Baird and Tatlock Ltd., P.O. Box 1, Romford, Essex RM1 1HA. Water Quality Monitor The Model 7975 self-checking, micro- processor-based water quality monitor can operate at an unmanned site for long periods, simultaneously measuring up to six different parameters (water tempera- ture, pH, conductivity, dissolved oxygen, turbidity and air temperature) with high and low alarms for each of the six chan- nels. All of these data can be relayed to a central station by telemetry or landline or fed into a local data logger. Kent Industrial Measurements Ltd., Oldends Lane, Stonehouse, Gloucester- shire GLlO 3TA. Balances, Software and Peripherals A special applications package, LabPac- M, for the makers’ AM/PM series of electronic analytical and precision balances provides a formulating system.As soon as the target weight of the first component has been keyed in, the balance switches the built-in DeltaTrac secondary analog display to overiunder mode. The required quantity can then be weighed in exactly, without having to watch the digital display. With a printer connected to the balance, each step of the formulation is recorded. The new AM analytical series of balances are equipped as standard with all the features of the -M technology previously available with only the PM series, such as a selectable vibra- tion adapter and permanently programmed applications for counting, per cent. weighing, plusiminus, a selec- tion of weight units and an interface allowing connection to peripheral instru- ments.The PM range of precision balances covers a readability span of 0.001 to 1 g and weighing ranges between 0-100 g and 0-30 kg. Included in this range of 17 balances are four DeltaRange models. Accessories and peripherals include the LP16 infrared dryer, LVl0 automatic feeder, Application Pacs and LabWare. Also available is the SM range of scales with weighing ranges up to 12 kg and all incorporating the -M technology. The TE range of scales consists of 10 models with capacities from 6 to 120 kg. Five models are multi-functional for weighing, count- ing, compounding and checkweighing; the other 5 are basic grosshet scales. Mettler Instrumente AG, CH-8606 Greifensee, Switzerland. Electronic Analytical Balances The Ohaus Galaxy range of balances enables accurate measurements as small as 0.1 mg to be taken over the entire weighing range.The weighing chamber is accessible via any of 3 glass sliding doors. Three models are available: 2 single range balances with weighing ranges of 110 and24 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 160 g and a dual-range model of 30 or 160 g, with the 30-g range accurate to 0.01 mg. BDH Ltd., Apparatus Division, P.O. Box 8, Dagenham, Essex RM8 1RY. Helium Leak Detector Ready for use in 3 min, the portable HLT 100 is easy to use and has no need for liquid nitrogen. One of Cambridge Mass Spectrometry's instruments, a laser ioni- sation mass analyser, was leak limited, reducing its maximum operatjng pressure from 10-9 to 10-5 Torr. Following various other tests the HLT 100 was brought in, rapidly pinpointing a faulty component Photometric Analyser The Vitalab 10 is a universal filter pho- tometer capable of accommodating all types of square cuvettes, including low volume drain cell cuvettes, and most round test-tube and flow cell types.It has fully automatic zeroing and calibration and its design allows the addition of the makers' alphanumeric DPU 40 printer. It is suitable for both routine clinical and industrial use. Vital Scientific Ltd., Huffwood Trad- ing Estate, Partridge Green, West Sussex RH13 8AU. Surface Analysis Instruments The Series 900 surface analysis instru- ments are modular in design. The S930 features a mass filtered Duoplasmatron source for dynamic depth profiling and dopant studies, and a pre-filtered Quad- rupole Mass Analyser for maximum sensi- tivity across a wide mass range.A selec- tion of microfocused liquid metal ion guns provide high resolution (30Ck50 nm) SIMS imaging. In static SIMS the makers' range of scanning FAB and inert gas ion guns provide sub-monolayer sensitivity for the precise chemical analysis of sur- faces. Instrument automation of acquisi- tion and analysis, advanced depth profi- ling and image processing are handled by the user friendly DS800 control and data system. Kratos Analytical, Barton Dock Road, Urmston, Manchester M31 2LD. logue and pulse re-transmission signals. The meter is self-contained and requires no secondary instrumentation. Kent Industrial Measurements Ltd., Oldends Lane, Stonehouse, Gloucester- shire GLl0 3TA. Flow Measurement System A three-component flow measurement system combines thermal anemometry techniques with a new data analysis algorithm to provide an accurate method for taking 3-D hot-wire and hot-film measurements.Although designed for 3-D flows, the system is also suitable for single and/or x-sensor analysis. A typical 3-D system includes a three-sensor probe, a computer-controlled three-channel ane- mometer with associated signal condition- ers, a temperature module, a high speed multi-channel digitiser and a data analysis software package. The addition of appropriate components allows expan- sion of the system up to 16 channels. BIRAL, P.O. Box 2, Portishead, Bris- to1 BS20 7JB. Ultrasonic Processors The Vibra-cell processes a wide range of samples and volumes from microlitres to gallons, preparing emulsions down to 0.01 pm, homogenising liquids, dissolving dif- ficult compounds and catalysing chemical and enzymatic reactions.Four different Vibra-cells are available for applications ranging from small-scale laboratory use with volumes as low as 100 p1 to process- ing larger biological samples and chemical processing up to a maximum of 200 Programmer for Baths and gallons. Other uses include preparing Circulators and its porous weld. Customers can hire The PZ1 programmer is an addition to the samples for particle size analysis, de- the detector complete with a 4 m3 h-' Barrington range of thermostatic gassing liquids and disaggregating par- pump, sniffer probe with 3-m hose, c a b instrumentation. Simple to operate, it ticulates.rated test leak, selection of adapter features digital setting and display span- Roth Scientific c o . Ltd., Alpha House, flanges with connection hose, and remote ning from -40 to +300 "C and stores up to 9-11 Alexandra Road, Farnborough, audio-visual indicator with 5 m cable. ten temperature profiles. With automatic Hampshire GU14 6BU Ba1ze1-s High Vacuum Ltd., North- switch-off and an alarm to indicate end- bridge Road, Berkhamsted, Hertford- of-program condition, the programmer signal ~~~l~~~~ shire HP4 1EN. to be set to repeat to HewJett-Packard's 3561A dynamic signal analyser, designed to meet spectral analy- nine times; these can to three Heat Flux Differential Scanning heating/cooling (l-looO OC sis test needs in electronics, vibration Calorimeter and four periods Of up to loo h.An analysis and acoustics applications, is program function available on hire. A purchase option plan allows the user to spread capital outlay or operating over the temperature range circulator fluid temperature differs from to evaluate equipment before purchasing. from -150 to +700 "C and can be used in the set value by a fully integrated computer system or start of each hold period. There is an Electroplan Rental catalogue. simply with a potentiometric recorder. Electroplan Rental, P.O. Box 19, Transported on the back of an estate Barrington, Grant Instruments Cambridge CB2 5QZ. Ltd*7 Orchard Road, Royston, Hertfordshire vehicle, a DSC 700 has successfully under- The DSC 70° analyser is capab1e Of comes into operation if the bath or than Oe5 o c at the SG8 5HH.gone a series of working demmstrations on customers' premises in the UK, Ire- land, Belgium and Sweden during a recent 4000-mile itinerary. The unit wor- ked well under field conditions through- out the tour. On many occasions it was transferred from the cold interior of the estate car, where it had remained over- night, into a laboratory environment of 22-23 "C. Stanton Redcroft Ltd., Copper Mill Lane, London SWll OBN. Ultrasonic Flow Meter This instrument is available in sizes from 200 mm to 2 m in diameter. It is suitable for measuring the flow of relatively clean fluids at process temperatures from -20 to + 100 "C and it can accommodate pres- sures up to 16 bar with an accuracy of k 1% of reading. It is suitable for any flow range between 0-1 m s-1 and 0-10 m s-1.Flow-rate indication and totalisation are provided as standard, along with ana- Plasma Analysis Kits A range of kits is available to make the analysis by HPLC of catecholamines in plasma fast, easy and convenient. Each kit is an integrated, pre-packed reagent system for the analysis of norepinephrine (noradrenalin), epinephrine (adrenalin) and dopamine. The kits are optimised for use with the Coulochem electrochemical detector. Analysis takes only 10 min and requires three simple steps.ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 25 Severn Analytical Ltd., Unit 2B, St. Francis’ Way, Shefford Industrial Estate, Shefford, Bedfordshire SG17 5DZ. Scanning Auger Microprobe The S820 scanning Auger microprobe (SAM) is designed to meet the semicon- ductor laboratory’s need for a dedicated instrument, compact and simple to oper- ate, with state-of-the-art performance specification (in excess of 60000 counts s-1 nA-1 on Cu LMM combined with spatial resolution of better than 50 nm).Burette A Morbank burette comes in a variety of sizes from 5 to 100 ml. The stopcock, key and barrel are all made from PTFE. The stopcock is joined to the burette by two screw-thread connectors, so that in the event of breakage the glass components can easily be replaced. J. Bibby Science Products Ltd., Stone, Staffordshire. Slimline Bottle A new straight-sided 60-ml container, the Kratos S820 scanning Auger microprohe Moreover, the rasterable, differentially pumped ion gun allows the system to be used as a highly sensitive, depth profiling, thin-film analyser.An energy dispersive X-ray detector is offered as an option to facilitate simultaneous Auger (surface) and EDX (bulk) analysis capability. Kratos Analytical, Barton Dock Road, Urmston, Manchester M3 1 2LD. Clinical Chemistry Analysers Vitalab 21 is programmable for up to 30 tests, and the 32 pl cell volume keeps reagent consumption low. The Vitalab 30 series, incorporating automatic wavelength selection, multi-function video display, a printer, a programmable 21 test memory and a sipper pump are available with plug-in filters (Vitalab 30), 8-position automatic filterwheel (Vitalab 31) or with monochromator (Vitalab 32). All models are fitted with curve fitting software for non-linear tests and all can be converted into the 100 series of chemistry batch analysers by the addition of a sampler and programmable diluter.The Vitalab 200 patient profile analyser can perform up to 12 tests at a time from a menu of 40 different methods. After loading, it calculates the fastest running sequence, performs quality control checks and can carry out up to 72 tests h-1. A range of osmometers and the Orion 10/20 ISE analyser for sodium and potassium are also available. Vital Scientific Ltd., Huffwood Trad- ing Estate, Partridge Green, Sussex RH13 8AU. 60 ml Plus Tall, is taller and slimmer than the normal 60-ml container and is avail- able with a wide variety of caps and labels, sterile or unsterile. Medfor Products, 15 King’s Road, Fleet, Hampshire GU13 9AA. Laboratory Information Handling Systems Five new products are announced. The PC Integrator is a dual-channel system for data acquisition, storage, integration, reporting, plotting and re-integration.By use of simple menu screens and his own selected values, the chemist can process chromatography data to final report stage, while at the same time using the PC to run a third-party program such as LOTUS 1-2-3. Turbochrom is a PC-based chromatography workstation. ACCESS- *Chrom is a multi-tasking chromato- graphy software package which runs on DEC VAX and MicroVAX I1 minicom- puters; using VMS-based software, it provides a centralised chromatography data reduction package running on DEC hardware. ACCESSkLIMS is a modular laboratory information management system fully compatible with the makers’ chromatography workstation and other mini-based systems and can be connected to them via Ethernet.Finally, a new multi-level networking facility, Open Architecture Network, allows maximum use to be made of many computing resources within the laboratory, enabling users to access the network from any location in the laboratory or from any level in the hierarchy of bench work- stations. Nelson Analytical Ltd., 860 Birchwood Boulevard, Birchwood, Warrington, Cheshire WA3 7QZ. Compressed Air Dryers Two small capacity ranges of desiccant dryers, the Mini and Midi Pneudri, are compact, offering a 60% space saving on conventional units of the same capacity. The Mini range, consisting of four models, covers air flow capacities from 3 to 15 scfm and the Midi range, with nine models, covers capacities from 20 to 160 scfm. Desiccant dryers will typically give pressure dewpoints of from -40 to -70°C. Delivered air quality can be guaranteed by using the makers’ OIL-X filters, the Grade AA pre-filter giving particulate removal down to 0.01 pm with oil mist less than 0.01 mg m-3.A Grade AC prefilter will provide compressed air containing oil vapour less than 0.003 mg m-3. For compressed air of the finest quality the makers offer the Pure-Dri, a 4-stage unit. By adding extra towers to this modular dryer its flow capacity can be increased in steps from 100 to 1600 scfm. Domnick Hunter Filters Ltd., Durham Road, Birtley, County Durham DH3 2SF. Chromatography Instruments The SFC3000 is a supercritical fluid chro- matograph system with programmable injection and a data station for instrument control as well as data acquisition.It is equipped with the makers’ on-column injector and an FID detector. A series of Maxima GC workstations allow instru- ment control and data acquisition. Word processing or spreadsheet calculations can be carried out in the foreground while data are acquired in the background mode. A range of dedicated gas analysers is also announced. Based on a 3-valve system fitted to the Vega and Mega series26 ANALYTICAL PROCEEDINGS, JANUARY 1988. VOL 25 of gas chromatographs, they can carry out a wide range of gas analysis (natural gas, TOGA, etc.). The “0” FID gas chromat- ography detector is responsive to oxygen- ated compounds and has been developed for the petroleum industry.A peroxy- acetyl nitrate analyser has also been developed. Also announced is Baseline, a new IBM based gas chromatography workstation complete with mouse-driven pull-down graphics, true multi-tasking, dual-channel operation, 22-bit interface and hard-disk storage. Carlo Erba Instruments (UK), MSE, Sussex Manor Park, Gatwick Road, Crawley RHlO 2QQ. Surface Area Analyser The Sorptomatic 1900 is based on an automatic multi-point BET principle and can be used to provide pore size informa- tion, surface area measurement, specific surfaces and chemical mapping of sur- faces. It is a modular system to which may be added a chemisorption unit, a krypton unit, a quadrupole thermal mass detector and an IBM based data processor. Carlo Erba Instruments (UK), MSE, Sussex Manor Park, Gatwick Road, Crawley RHlO 2QQ.Safelab Systems A range of products is announced: all- PTFE - FEP - PFA distillation systems with a range of six pore-free pure PTFE reaction vessels from 500 to 6000 ml; Bohlender’s range of fluoroplastics labor- atory ware, consisting of bottles, beakers, jars, tubing and PTFE, PPH and glass Safe-Lab stoppers; Chemoflex, Spira- chem, Multichem and Chemoline flex- ible, corrugated or helically convoluted special PTFElFEPiPFA hoses from Maag Technic AG of Switzerland; PTFE spray and PTFE paint, which can be brushed on to any metal surface; metal crucibles precision drawn from zirconium, inconel, nickel, molybdenum or tantalum; Basic and Super Chemisorb respirators; the Chemiscape emergency escape hoods; and the survivor escape - re-entry - rescue hoods.Safelab Systems Ltd., Bush House, 72 Prince Street, Bristol BS1 4HU. Literature A brochure, “Products for XRF ICP Sample Preparation,” describes materials and applications for spectrographic analy- sis. There is a section on the care and maintenance of precious metal laboratory apparatus. A comprehensive range of product information sheets outline the types of apparatus available, with recom- mended sizes, weights and materials listed in tables for easy reference. Johnson Matthey Materials Technol- ogy Division, Noble Metals Business Unit, Fourth Way, Exhibition Grounds, Wembley, Middlesex HA9 OHW. Literature is available on the TBT- Orthodyne range of chromatographs. Brochures describe the Argon chromato- graphs and a range of detectors, and examples are given of chromatograms obtained.Orthodyne s.a., Avenue de ]’Union, 25 , B-4300 Liege/Ans, Belgium. Three brochures on HPLC columns are announced. The first gives details of the complete Chrompack HPLC range and describes the 18 different packing materials available both in conventional stainless steel columns and in the new modular ChromSep HPLC columns. The other two feature new products: the high speed, high efficiency columns for fast high resolution HPLC separations and the new ChromSpher PAH column for the analysis of polycyclic hydrocarbons. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London E l 4 9TN. A brochure gives details of the Kemtek 700 compact automated liquid handling system, which is ideally suited to medical and industrial sample preparation.Com- patible with a wide range of computers, it is supplied with comprehensive software, and information is available on the pro- vision of customised software. Another brochure describes the Kemtek 1000 total liquid handling system. A number of optional extras, including a tube washer, a plate washer and a carousel and bar-code reader, are available. The Kemble Instrument Co. Ltd., Albert Drive, Burgess Hill, Sussex RH15 9NB. An application note, Number 810. gives information on determining the thermal characteristics of PVC by means of the makers’ FP85 DSC measuring cell in conjunction with the FP80 control unit. Using the FP85 it is possible, with the aid of the DSC curve, to determine the vitrification temperature and hence the proportion of plasticiser in the plastic. Mettler Instrumente AG. CH-8606 Greifensee, Switzerland. Literature presents details of the Visidry drying attachment for the Visiprep solid phase extraction vacuum manifold. Readily installed on the vacuum mani- fold, it prevents water from contaminat- ing normal-phase eluents and enables the operator to dry the packing bed in up to 12 samples at one time. Supelco Inc., Supelco Park, Bellefonte, PA 16823-0048, USA. An illustrated brochure describes the Model L7-65, a 65 000 rev min-* ultra- centrifuge for studies of nucleic acids and other biological materials. It lists the 36 preparative ultracentrifuge rotors that can be used with the L7-65 and explains the best possible processing efficiency via carrier belts available with the bowl rotor. A booklet provides information on appli- cations for the TL-100 benchtop ultracen- trifuge. Arranged in the form of a conti- nuing bibliography with annotations, arranged by subject, documenting the use of rapid ultra-centrifugation for small samples, it includes the following head- ings: binding studies, DNA, lipoproteins, proteins, RNA, sub-cellular fractions, translation reaction proteins and viruses. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire. A new short-form catalogue, for 1987-88, offers a source of information on a wide range of electro-optical laboratory equip- ment, from fibre optics to scientific and industrial lasers. Lambda Photometrics Ltd., Lambda House, Batford Mill, Harpenden, Hert- fordshire AL5 5BZ.

ISSN:0144-557X    

DOI:10.1039/AP9882500022

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

26 ANALYTICAL PROCEEDINGS, JANUARY 1988. VOL 25 Verein Deutscher lngenieure Guidelines VDI 2267. Part 4: Chemical Analysis of Particulates in Ambient Air. Determina- tion of Lead, Cadmium and Their Inor- ganic Compounds as Part of the Dust Precipitation by Atomic Absorption Spectrometry. Part 6: Chemical Analysis of Suspended Particulates in Ambient Air. Measurement of the Mass Concen- tration of Cadmium by Atomic Absorp- tion Spectrometry. VDI 2268. Part 1: Chemical Analysis of Particulate Matter. Determination of Ba, Be, Cd, Co, Cr, Cu, Ni, Pb, Sr, V, Zn in Particulate Emissions by Atomic Spec- trometric Methods. VDI 2452. Part 3: Gaseous Air Pollution Measurement. Measurement of Fluoride Ion Concentration. Sorption Method with Prepared Silver Balls and Heated Mem- brane Filter.VDI 2463. Part 9: Particulate Matter Measurement. Measurement of Mass Concentration in Ambient Air. Filter Method. LIS/P Filter Device.ANALYTICAL PROCEEDINGS, JANUARY 1988. VOL 25 27 The North West Region of the RSC Analytical Division and MacroGroup UK Announce a Joint One Day Meeting on RECENT ADVANCES IN POLYMER CHARACTERISATION to be held on Wednesday May 25th 1988 at the ICI Health Site Conference Centre, Runcorn, UK from 10.15 am to 5.45 pm Prof. G. Zerbi (Politecnico di Milano)-IR - Raman Spectroscopy Prof. D. E. Games (Univ. College, Cardiff)-Supercritical Fluid Chromatography Prof. J. V. Dawkins (Univ. of Loughborough)-Coupled Column Chromatograph\ Prof. R. J. Young (UMIST)-Raman Microscopy Prof. K. J. Packer (British Petroleum)-Solid State NMR Dr.D. Briggs (ICI Wilton Materials Centre)-Polymer Surface Analysis Dr. T. Hammond (Foseco Int/Univ. of Birmingham)-Pyrolysis GLC of Polymers Dr. J. H. Scrivens (ICI Wilton Materials Centre)-Polymer Mass Spectrometry Registration (including lunch and refreshments): Members of RSC or MacroGroup UK €45.00 Non-members of RSC or MacroGroup UK f65.00 Full Time Students or Retired Members of RSC o r MacroGroup UK f 15.00 For Full Details and Registration Forms Please Contact: Mr. R. G. Feasey, ICI Chemicals and Polymers Group, The Heath, P.O. Box 8, Runcorn, Cheshire WA7 4QG (Tel. 0928 51 1133)28 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 VDI 3863. Part 1: Measurement of Prevention of the VDI. The loose-leaf end of 1982 have been bilingual in Ger- Gaseous Emission. Determination of guidelines have been combined to form man and English. VDI Guidelines can be Acrylonitrile. Gas Chromatographic the “Manual on Air Pollution Preven- obtained from Beuth-Verlag GmbH, Method. Grab Sampling. tion,” although they are all available P.O. Box 1145, D-1000 Berlin 30, Federal The above guidelines are all produced separately. Guidelines produced since the by the Commission on Air Pollution Republic of Germany.

ISSN:0144-557X    

DOI:10.1039/AP9882500026

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

28 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Publications Received Toxicological Evaluation of Certain Food Additives and Contaminants. Prepared by The 29th Meeting of the Joint FAO/WHO Expert Committee on Food Additives. WHO Food Additives Series, 20. Pp. viii + 286. Cambridge University Press. 1987. Price f19.50; $24.95. ISBN 0 521 34347 X. Infrared Spectroscopy. W. 0. George and P. S. McIntyre. Analytical Chemistry by Open Learning. Pp. xx + 537. Wiley. 1987. Price f17.50 (paperback); $44; $87 (cloth). ISBN 0 471 91383 9 (paperback); 0 471 91382 0 (cloth). Industrial Applications of the Mossbauer Effect. Edited by Gary J. Long and John G. Stevens. Pp. x + 796. Plenum. 1986. Price $115. ISBN 0 306 42463 0. Analytical Aspects of Ozone Treatment of Water and Wastewater. Rip G.Rice, L. Joseph Bollyky and William J. Lacy. Pp. xiv + 413. Lewis Publishers, 1987. Price f49.25. ISBN 0 87371 064 9. The Art of Scientific Writing. Hans F. Ebel, Claus Bliefert, William E. Russey. Pp. xix + 493. VCH. 1987. Price DM48 (softcover); DM98 (hardcover). ISBN 3 527 26677 1 (VCH Verlags- gesellschaft); 0 89573 645 4 (VCH Pub- lishers). Introduction to Nondestructive Testing. A Training Guide. Paul E. Mix. Pp. xvi + 406. Wiley-Inter- science. 1987. Price f50.45. ISBN 0 471 83126 3. Analysis of Surface Waters. Hubert Hellmann. Ellis Horwood Series in Water and Wastewater Technology. Pp. 275. Ellis Horwood. 1987. Price f45. ISBN 0 7458 0213 3 (Ellis Horwood); 0 470 20924 0 (Halsted Press). Mass Spectrometry. Reg Davis, Martin Frearson. Analytical Chemistry by Open Learning.Pp. xviii + 603. Wiley. 1987. Price f17.50. ISBN 0 471 91389 8 (paperback); 0 471 91388 X. Classical Methods, Volume 2. John Mendham, David Dodd, Derek Cooper. Analytical Chemistry by Open Learning. Pp. xxii + 351. Wiley. 1987. Price f11.50. ISBN 0 471 91365 0; 0 471 91364 2. On-Column Injection in Capillary Gas Chromatography. Basic Technique, Retention Gaps, Solvent Effects. Konrad Grob. Chromatographic Methods. Pp. xx + 591. Huthig, 1987. Price DM188. ISBN 3 7785 1551 9. Apple I1 in the Laboratory. A. F. Kuckes and B. G. Thompson. Pp. x + 206. Cambridge University Press. 1987. Price f25; $37.50. ISBN 0 521 32198 0. Analytical Procedures for Therapeutic Drug Monitoring and Emergency Toxicol- ogy. Second Edition. Randall C. Baselt.Pp. x + 329. PSG Publishing Co. 1987. Price f34; ISBN 0 88416 722 4. Physical Methods of Chemistry. Second Edition. Volume IIIA. Determination of Chemical Composition and MolecularANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 29 KINETICS IN ANALYTICAL CHEMISTRY The third in this series of international symposia will be held in Cavtat, near Dubrovnik, Yugoslavia, on September 25-28, 1989. The organisers will be The Serbian Chemical Society. The scientific programme, which w i l l take place in the Croatia Hotel, will consist of plenary, invited and contributed papers and posters. The subject matter will include catalytic (enzymatic or non-enzymatic) and non-catalytic methods, differential reaction rate methods and unsegmented flow methods. The scientific committee is as follows: Professor H.A. Mottola (Stillwater, Oklahoma, USA); Professor G. Werner (Leipzig, GDR); Professor M. Valcarcel (Cordoba, Spain); Professor M. I . Karayannis (loannina, Greece); Professor G. A. Milovanovic (Belgrade, Yugoslavia); and Professor F. F. Gaal (Novi Sad, Yugoslavia). For further information concerning the conference contact Professor Gordana A. Milovanovic, Department of Chemistry, University of Belgrade, KAC, P.O. Box 550, 11001 Belgrade, Yugoslavia. 1988 The Fourth Biennial National Atomic Spectroscopy Symposium will be held at the University of York on 29 June - 1 July 1988 Plenary lectures will be given by: Dr A L Gray, Prof G M Hieftje, Dr N Omenetto, Dr M Thompson and Dr A P Thorne. There will also he invited lectures, submitted lectures and posters, an exhibition and a full social programme.Further infimnution can be obtained from: Dr Neil Barnett, Dept of Environmental Sciences, P 1 y mo 11 t h Pc 1 y t e c h n i c , Drake Circus , I'lyn~outh PL4 8AA. DIFFUSIVE AN ALTERNATIVE APPROACH TO WORKPLACE AIR MONITORING EDITED BY A BERLIt\I. R H BROWN, and K J SAUNDERS DIFFUSIVE SAMPLING Hardcover SOOpp ISBN 0 85186 343 Price E4S.00 $87.00 RSC Members Price €27.00 Diffusive Sampling is based on a symposium held in Luxembourg in September 1986 and organised jointly by the Commission of the European Communities and the United Kingdom Health and Safety Executive in cooperahon with the World Health Organization and the Royal Society of Chemistry. 0 Reviews the state of the art of diffusive sampler techniques 0 Stimulates the exchange of technical information 0 Assess the suitability and range of applications for workplace monitoring 0 Promotes the further development of this technique and its wider use.Ordering: RSC Members should send their orders to The Royal Society of Chemistry. Membership Manager, 30 Russell Square, London WCI B 5DT. U K Non RSC members should send their orders to The Royal Society Letchworth, Herts SG6 IHN, U K of Chemistry, Distribution Centre, Blackhorse Road30 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Structure-Part A. Edited by Bryant W. Rossiter, John F. Hamilton. Pp. xiv + 624. Wiley-Inter- science. 1987. Price f100.90. ISBN 0 471 85041 1. Spectroscopy of Inorganic-Based Materials. Edited by R. J. H. Clark and R.E. Hester. Advances in Spectroscopy, Vol- ume 14. Pp. xx + 472. Wiley. 1987. Price f79.95. ISBN 0 471 91483 5. xiv + 272. Wiley-Interscience. Price f59.65. ISBN 0 471 85884 6. Flavour Science and Technology. Proceed- ings of the 5th Weurman Flavour Research Symposium, held at the Sara Hotel, Volksendsen, Oslo, 23rd-25th March, 1987. Edited by M. Martens, G. A. Dalen and H. Russwurm Jr. Pp. xvi + 566. Wiley. 1987. Price 540. ISBN 0 471 91743 5. Cadmium in the Aquatic Environment. Edited by Jerome 0. Nriagu and John B. Sprague. Advances in Environmental Sciences and Technology, Volume 19. Pp. \. Using Literature. Stuart James. Analytical Chemistry by Open Learning. Pp. xvi + 598. Wiley. 1987. Price f17.50 (paperback); E44 (cloth); $87.50. ISBN 0 471 91221 2 (PaDerback): 0 471 91220 4 (cloth). Fluorescence and Phosphorescence. David Rendell. Analytical Chemistry by Open Learning. Pp. xx + 419. Wiley. 1987. Price f13.95. ISBN 0 471 91381 2. Applications of Mass Spectrometry in Food Science. Edited by John Gilbert. Pp. xxii + 440. Elsevier. 1987. Price f60. ISBN 1 85166 081 x. Inductively Coupled Plasmas in Analytical Atomic Spectrometry. Edited by Akbar Montaser and D. W. Golightly. Pp. xxvi + 660. VCH. 1987. Price DM215. ISBN 0 89573 334 X (VCH Publishers); 3 527 26529 5 (VCH Verlags- gesellschaft) .

ISSN:0144-557X    

DOI:10.1039/AP988250028b

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

30 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Courses Chromatography Workshops 1988 The Chromatographic Society will be holding two Workshops on Chromato- graphy. A HPLC Workshop will be held on April 11-15, and a GC Workshop will be held on July 18-22. Both will be held in Guildford. Further details are available from the Executive Secretary, Chromatographic Society, Trent Polytechnic, Burton Street, Nottingham NG1 4BU. Flowmeter Selection, Calibration and Application April 13-14 and 18-19, 1988, Amsterdam and London IBC Technical Services Ltd. will be organising these two-day seminars. The Amsterdam course will be held at the Amsterdam Hilton Hotel, while the Lon- don course will take place at the Portman Intercontinental Hotel. For further information contact Carol Gerrard, IBC Technical Services Ltd., Bath House (3rd Floor), 56 Holborn Viaduct, London EClA 2EX.Basic Microbiological Methods and the Analytical Chemist April 18-22, 1988, Loughborough The Microbiology Section of the Che- mistry Department of the University of Technology will be running the above residential one-week course. The cost will be f450 for residents and f395 for non- residents. The course will concentrate on practical aspects of microbiology, with a strong emphasis on counting and identifi- cation of bacteria from a variety of sources. The concepts of sterility testing will also be studied. Further details are available from Dr. R. K. Dart at the Department of Che- mistry, Loughborough University of Technology, Loughborough, Leicester- shire LE11 3TU.30 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Courses Chromatography Workshops 1988 The Chromatographic Society will be holding two Workshops on Chromato- graphy.A HPLC Workshop will be held on April 11-15, and a GC Workshop will be held on July 18-22. Both will be held in Guildford. Further details are available from the Executive Secretary, Chromatographic Society, Trent Polytechnic, Burton Street, Nottingham NG1 4BU. Flowmeter Selection, Calibration and Application April 13-14 and 18-19, 1988, Amsterdam and London IBC Technical Services Ltd. will be organising these two-day seminars. The Amsterdam course will be held at the Amsterdam Hilton Hotel, while the Lon- don course will take place at the Portman Intercontinental Hotel. For further information contact Carol Gerrard, IBC Technical Services Ltd., Bath House (3rd Floor), 56 Holborn Viaduct, London EClA 2EX. Basic Microbiological Methods and the Analytical Chemist April 18-22, 1988, Loughborough The Microbiology Section of the Che- mistry Department of the University of Technology will be running the above residential one-week course. The cost will be f450 for residents and f395 for non- residents. The course will concentrate on practical aspects of microbiology, with a strong emphasis on counting and identifi- cation of bacteria from a variety of sources. The concepts of sterility testing will also be studied. Further details are available from Dr. R. K. Dart at the Department of Che- mistry, Loughborough University of Technology, Loughborough, Leicester- shire LE11 3TU.

ISSN:0144-557X    

DOI:10.1039/AP988250030b

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

32 ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 Analytical Division Diary JANUARY Wednesday, 27th, 4 p.m.: Belfast Northern Ireland Region. Laser Spectroscopy. Queen’s University, Belfast. Contact: Mr. W. J. Swindall, Department of Chemistry, David Keir Building, Queen’s University, Belfast BT9 5AG. (Tel. 0232-661111, Ex. 4428). Thursday, 28th, 4 p.m.: London Automatic Methods Group: Annual General Meeting. 21 Years in Automation. Speaker: D. Betteridge. Whitbread Conference Centre, London. Contact: Dr. C. J. Jackson, Health and Safety Executive, Research Laboratory Services Division, Broad Lane, Sheffield S3 7HQ. (Tel. 0742-768141, Ex. 3302). Friday, 29th: Plymouth Western Region. Theophilus Redwood Lecture. Speaker: A. Townshend. The Polytechnic, Plymouth. Contact: Mr. F.W. Sweeting, Wessex Water Authority, Regional Scientific Centre, Mead Lane, Saltford, Bristol BS18 3ER. (Tel. 0225-873692, Ex. 144). FEBRUARY Tuesday, 2nd, 4.15 p.m.: Loughborough Midlands Region, jointly with the East Midlands Section of the RSC and the Loughborough Students Chemical Society . Flow Injection Analysis-The First Decade. Speaker: A. Townshcnd. Lecture Theatre JOOl , Edward Herbert Building, University of Technology, Loughborough. There are no registration formalities. Contact: Mr. H. E. Brookes, 35 Dunster Road, West Bridgford, Nottingham NG2 6JE. (Tel. 0602-231769). Thursday, 4th, 9.30 a.m.: London the Chromatographic Society. Chromatography and Electrophoresis Group, jointly with Chromatography in Occupational Hygiene. “Occupational Hygiene-The Need for Reliable Analytical Infor- mation: An Overview,” by J.Bridges. “Experiences from an Independent Consultancy Practice of the Use of Chromatography in Questions of Occupational Hygiene,” by Diana Simpson. “Chromatography in Occupational Hygiene-The Hygienist View,” by S. J . Lewis. “An Improved Method for the Determination of Ethylene Oxide in Air, Using 3M’s Diffusion Samplers,” by P. E. Tindle. “New Perspectives in Diffusive Sampling,” by R. H. Brown. “Operator Exposure to Agrochemical Sprays,” by D. S. Stevenson and T. McDonald. “Introducing the New HSE Workplace Analytical Scheme for Proficiency (WASP) for Occupational Hygiene Laboratories,” by N. L. West. Royal College of Surgeons, 35 Lincoln’s Inn Fields, London, w . c . 2 . Registration is necessary.Cost f31.50 to members and f46 to non-members. Contact: The Executive Secretary, The Chromatographic Society, Trent Polytechnic, Burton Street, Nottingham NG1 4BU. (Tel. 0602-48248). Thursday, 4th, 4 p.m.: Glasgow Scottish Region, jointly with the Glasgow and West of Scotland Section of the RSC and the Andersonian Society. Flow Injection Analysis-The First Decade. Speaker: A. Townshend. Department of Pure and Applied Chemistry, Thomas Graham Building, University of Strathclyde, Cathedral Street, Glasgow. There are no registration formalities. Contact: Dr. J. M. Warren, Department of Biochemistry, Royal Infirmary, Glasgow G4 OSF. (Tel. 041-552-3535, Ex. 5178). Tuesday, 9th, 4.15 p.m.: Loughborough Midlands Region, jointly with the East Midlands Section of the RSC and the Loughborough Students Chemical Society.The Scientific Investigation of Shoot ings. Speaker: R. Keeley. Lecture Theatre JOOl , Edward Herbert Building, University of Technology, Loughborough. There are no registration formalities. Contact: Mr. H. E. Brookes, 35 Dunster Road, West Bridgford, Nottingham NG2 6JE. (Tel. 0602-231769). Wednesday, loth, 2.15 p.m.: London Analytical Division. Alternative Methods for Trace Elements. “Some Aspects of ICP - MS in Food Analysis,“ by D. J. McWeeny. “Automated, Continuous-flow Analysis of Trace Metals in Water Using Stripping Chronopotentiometry,” by C. M. G. van den Berg. “HPLC Determination of Trace Metals,” by Phil Jones. “Chemical Analysis at Solid Surfaces,” by Jeremy Ness and D. J . Joiner. Scientific Societies Lecture Theatre, 23 Savile Row (entrance in New Burlington Place), London W.l.Registration is necessary. Cost &7 to members, f15 to non-members and f 2 to student and retired members. Contact: Miss P. E. Hutchinson, Analytical Division, Royal Society of Chemistry, Burlington House, London W1V OBN. (Tel. 01-437-8656). Thursday, llth, 10.30 a.m.: London Biological Methods and Automatic Methods Groups. Automated Microbiological Analysis. Chairman’s Introduction by M. C. Easter. “ AMBIS-a Novel System for Microbiological Identification,” by “Rapid Enumeration of Micro-organisms in Biological Fluids by S. Tabaqchali. Automated Fluorescence Microscopy,” by J . Scholefield. [continued inside back cover]ANALYTICAL PROCEEDINGS, JANUARY 1988, VOL 25 ... 111 Analytical Division Diary, continued February, continued *‘Multipoint Techniques for Antibiotic Susceptibility, Bacterial “Rapid Detection and Identification of Bacteria in Drinking Water “Role of Rapid Microbiological Techniques in the Food Industry.” Summing up by M.C. Easter. The Robin Brook Centre, St. Bartholomews Hospital, London. Registration is necessary. Cost f10 to members, f15 for non-members and f 8 for student, retired and unemployed members. Contact: Mr. A. J. Crooks, VRPL, PHLS, CAMR, Porton Down, Salisbury, Wiltshire SP4 OJG. (Tel. 0980-610391, Ex. 382). Identification and Radial Haemolysis,” by P. S . Pover. by Conductivity Measurement,” by G . Jones. by M. R . Adams and C. F. A. Hope. Wednesday, 17th, 6.30 p.m.: London Micro & Chemical Methods Group and South East Region.Discussion on Sample Preparation, with Particular Reference to Food Analysis. Introduced by Miss L. Dixon. Room A.506, The London School of Economics, Houghton Street, London W.C.2. There are no registration formalities. Contact: Mr. P. R. W. Baker, 55 Braemar Gardens, West Wickham, Kent BR4 OJN. (Tel. 01-777-1225). Wednesday, 24th, 1.25 p.m.: Hull North East Region. Process Analysis. “On-line Process Gas Chromatography in a Research and Develop- “Process Analysis in the Steel Industry,” by W. R. Marris. Demonstration of Water Monitor. “Sensors in Process Analysis Applications,” by H. Thompson. ment Environment,” by J. Green. “Spectrophotometric Field Monitor for Water Quality Parameters,” by P. J . Worsfold and J . R. Clinch. Lecture Theatre A, School of Chemistry, The University, Hull.Registration is necessary. Cost f12 for RSC members, f25 for non-members and f 2 for retired members and students. Contact: Dr. P. J. Worsfold, School of Chemistry, The University, Hull HU6 7RX. (Tel. 0482-465469). Wednesday, 24th, 6.30 p.m.: Moreton North West Region. Clinical Trials. “Clinical Trials-The Clinical Assessment of New Drugs,” (speaker “Pharmacokinetics-The Quantitative Fate of Drugs,” by S. Toon. “Advances in Analytical Methodologies for the Determination of E. R. Squibb & Sons Ltd., Reeds Lane, Moreton, Wirral. Registration is necessary; no charge. Contact: Dr. L. A. Gifford, Department of Pharmacy, University of Manchester, Coupland 111 Building, Oxford Road, Manchester M13 9PL. (Tel. 061-273-7121, Ex. 5 178). to be announced). Drugs,” by F. Mullins. Thursday, 25th, 4.15 p.m.: Aberdeen Scottish Region, jointly with the Aberdeen and North of Scotland Section of the RSC and the Aberdeen Students Chemical Society. Analytical Microwave Spectroscopy: New Directions. Department of Chemistry, Aberdeen University, Meston Walk, Old Aberdeen. No registration formalities. Contact: Dr. J. M. Warren, Department of Biochemistry, Royal Infirmary, Glasgow G4 OSF. (Tel. 041-552-3535, Ex. 5178).

ISSN:0144-557X    

DOI:10.1039/AP9882500032

出版商:RSC    

年代:1988

数据来源: RSC