摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 77 SHORT PAPER Determination of Metals in Poly(viny1 chloride) by Atomic Absorption Spectrometry Part 2.* Determination of Lead and Magnesium in Samples of Poly(viny1 chloride) with a High Content of Alkaline Earths Miguel A. Belarra, Jesus M. Anzano, Felix Gallarta and Juan R. Castillo Department of Analytical Chemistry, Science Faculty, University of Zaragoza, Zaragoza, Spain This is a continuation of the study of the use of EDTA in ammonia solution to dissolve the precipitate formed when a sample of PVC with a high content of alkaline earths is attacked with sulphuric acid and hydrogen peroxide. The method is used to determine lead and magnesium, and is both rapid and reliable. Keywords: Poly(vin yl chloride) analysis; lead determination; magnesium determination; flame atomic absorption spectrometry Poly(viny1 chloride) (PVC) is now widely used, in part due to the use of stabilising agents.Many of these agents are metallic and, therefore, can be determined easily by atomic absorption spectrometry. However, not much work has been carried out in this area. To dissolve the sample, Mendiola et al.1 tested five different methods and found that treatment with sulphuric acid and hydrogen peroxide gave the most satisfactory results. Although in the Mendiola study, 30% mlm hydrogen peroxide was used, Taubinger and Wilson,* in a study that was later extended by the Analytical Methods Committee ,39 pointed out the advantages of using this reagent at 50% mlm. Using this procedure, lead,l calcium and barium,s cadmium and zinc,6 and tin8 have been determined in PVC by atomic absorption spectrometry.Difficulties arise in this type of attack when the PVC sample contains alkaline earths or lead, because, under these condi- tions, the corresponding insoluble sulphate precipitates out. Mendiola et al.1 solved this problem by centrifuging the precipitate, dissolving it in nitric acid and determining the elements in the two resulting solutions by atomic absorption spectrometry. This procedure considerably lengthens the determination. In Part 19 we proposed the use of EDTA in ammonia solution to dissolve the precipitate formed when a PVC sample containing appreciable amounts of alkaline earths or lead is attacked with sulphuric acid and hydrogen peroxide. It was found that calcium, aluminium and antimony could be determined rapidly by atomic absorption spectrometry using this method, and that the reagents used did not alter the atomic absorption of these metals if the analyte solution is sufficiently diluted and the correct conditions are maintained.In this work, the study was extended to include the determination of lead and magnesium by atomic absorption spectrometry in samples of PVC with a high alkaline earth content. Basic lead salts are amongst the most important stabilisers for PVC, while magnesium oxide gives it greater hardness and rigidity. The results obtained in determining these elements are comparable, both in speed and accuracy, to those for calcium, antimony and aluminium. * For Part 1 of this series, see reference 9.Experimental Reagents Concentrated sulphuric acid, sp. gr. 1.84. Hydrogen peroxide, 30% mlm. Concentrated ammonia solution, sp. gr. 0.89. EDTA solution, 4% mlV. Dissolve 4.00 g of EDTA (disodium salt) in 100 ml of water with a few drops of ammonia. Standard lead solution, 1000 pg ml-1. Dissolve 1.60 g of lead nitrate in 50 ml of 1% V/VHN03 and dilute to 1 1 with 1% V/V Standard magnesium solution, 1000 Fg ml-1. Dissolve 1 .OO g of magnesium in 25 ml of 6 M HC1 and then dilute to 1 1 with distilled water. All solutions were prepared with analytical-reagent grade chemicals and re-distilled water, and were kept in poly- ethylene containers. Solutions of lower concentrations of these reagents were prepared each day by diluting the standard solutions.HN03. Apparatus A Perkin-Elmer Model 3030 atomic absorption spectrometer fitted with the appropriate Pye Unicam hollow-cathode lamps was used. The standard system of nebulisation and the corresponding burner for an air - acetylene flame (10-cm slit) were used. The instrument parameters used in measuring the atomic absorption of lead and magnesium are given in Table 1. In determining magnesium, two different sets of working conditions were used. For the highest sensitivity (distance of burner below the optical axis 7.5 mm) there is only a small linear range and these conditions were only used for extreme dilutions of the sample. In all other instances, the conditions of lower sensitivity, but with a greater linear range, were preferred. Preparation of the Sample The sample preparation procedure described previously was followed .9 Procedure Determination of lead and magnesium using a calibration Calibration graphs in the concentration ranges indicated in Table 1 were prepared using standard solutions of these graph78 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL.2 Table 1. Instrument parameters used in the atomic absorption spectrometry Distance of the Working burner below rangel Sensitivity/ Element Wavelengthhm Lamp current/mA Flame optical axis/mm pg ml-1 pg ml-1 Lead . . . . . . 217.0 5 Air - acetylene 7.5 0-10 0.23 (pale blue, oxidising) (pale blue, oxidising) (pale blue, oxidising) Magnesium . . . . 285.2 6 Air - acetylene 25.0 0-2 0.016 285.2 6 Air - acetylene 7.5 0 .5 0.010 Table 2. Results of recovery assays Metal found in Element sample/mg Lead . . . . 2.29 2.34 1.99 2.34 1.84 2.53 Magnesium . . 1.04 1.23 1.13 0.97 0.97 1.24 Metal added mg 2.65 2.65 2.65 2.65 2.49 2.49 1.29 1.29 1.29 1.29 1.29 1.29 Total metal found mg 4.98 4.99 4.64 4.96 4.34 5.03 2.30 2.51 2.39 2.23 2.25 2.49 Recovery, % 100.8 100.0 100.0 99.4 100.2 100.2 Mean . , 100.1 98.7 99.6 98.8 98.7 99.6 98.4 Mean . . 99.0 elements. The sample solutions were diluted between 5- and 10-fold for the lead determinations and between 10- and a 100-fold for the magnesium determinations. Determination of lead and magnesium by standard additions The sample solutions were diluted five times for the lead determinations and ten times for magnesium. To a series of 25-ml calibrated flasks, add 20 ml of the dilute solutions together with increasing, known amounts of the elements to be determined, diluting finally to 25 ml with distilled water.Measurement conditions The sample solutions are nebulised and the atomic absorp- tions of lead and magnesium are measured under the conditions given in Table 1. For magnesium the distance of the burner below the optical axis was 25.0 mm when the standard solution was diluted 10-fold and 7.5 mm when it was diluted 100-fold. Results and Discussion Attack of the Sample The general characteristics of the dissolution of the samples were given in Part 1.9 Recovery assays of lead and magnesium were carried out. As PVC samples with known concentrations of the metals under investigation were not available, the assay was carried out by adding 1 ml of a solution of these metals to the sample before the dissolution.The dissolution was carried out as described previously, and the lead and magnesium contents were determined using calibration graphs as indicated in the procedure. The results are given in Table 2. The recoveries of lead were entirely satisfactory, but those of magnesium were slightly low. However, the difference is so small that significant losses of magnesium during the dissolution of the sample can be ruled out. Effect of the Reagents on the Atomic Absorption of the Elements In order to prepare calibration graphs for the pure solutions of magnesium and lead, the effect of the reagents used in the dissolution of the sample on the atomic absorption of magnesium and lead was studied.In the determination of lead, a dilution of the treated sample to a volume of 500 ml or more with distilled water is necessary, to ensure that there is no modification of the atomic absorption signal due to the presence of the reagents. A volume of 1000 ml or higher is necessary for the magnesium determination. Even under these conditions, when working under conditions of maximum sensitivity (distance of the burner below the optical axis 7.5 mm) certain very slight modifications of the signal are observed (slope modification of less than k 1%). Analysis of PVC Samples The method proposed here has been used to determine lead and magnesium in a sample of commercially available PVC with a high calcium content (ca. 10%). The lead and magnesium contents were known to be ca.2 and 1%, respectively. These two metals were determined, following the proposed procedure, using both a calibration graph and the standard additions method. The results are given in Table 3. The results obtained under the described working con- ditions for both lead and magnesium were acceptable com- pared with the known approximate percentages of these elements. The more dilute solutions had higher standard deviations as anticipated and, in general, the standard additions method proved to be less precise than the calibration graph method.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 79 Table 3. Determination of lead and magnesium in PVC Lead Magnesium Parameter Calibration graph Standard additions Calibration graph Standard additions Dilutionoforiginalsolution .. . . 1 + 4 1+9 Numberofdeterminations . . . . 8 6 Average value/g per 100 g . . . . 1.96 1.94 Range/g per 100 g . . . . . . . . 1.92-1.99 1.86-2.05 Standard deviatiodg per 100 g . . . . 0.029 0.074 Relative standard deviation, % . . 1.5 3.8 1+4 6 1.98 1-96-2.01 0.030 1.5 1+9 1 + 99 8 6 0.99 0.97 0.014 0.075 1.4 7.7 0.97-1.00 0.86-1.03 1+9 6 1.02 0.97-1.04 0.043 4.2 Table 4. Analytical conditions of determinations Minimum dilution of standard solution for which there is no effect Element from dissolution reagents Calcium . . . . . . 10-foldt Magnesium . . . . . . lo-foldt Antimony . . . . . . 2-fold Lead . . . . . . . . 5-fOId Aluminium.. . . . . 2-f0ld$ * For a 0.1-g sample and with an RSD of less than 2%.t Not working under conditions of maximum sensitivity.9 $ Addition of KC1 to solutions used to prepare the calibration graphs. Minimum metal that can be determined in Interference between PVC*, Yo metals studied 2 No 0.05 No 1 No 0.5 No 1 CaifCa:Al>l Conclusion From the results given here, and those previously in Part 1,9 we conclude that treatment with EDTA and ammonia dissolves the precipitate formed when samples of PVC with high contents of alkaline earths or lead are attacked with sulphuric acid. Under these conditions, determination by atomic absorption spectrometry of calcium, aluminium, anti- mony, lead and magnesium, at levels of ca. 1%, is both fast and precise. These measurements can be made against aqueous solutions of these elements by simply diluting the samples sufficiently.able 4 gives a summary of the results obtained. It can be seen that treatment with EDTA and ammonia can be used to determine lead and magnesium in samples of PVC with lower contents than those indicated in the Table; the sample solution is simply diluted less, but in these instances the calibration graphs must be prepared with the dissolution reagents present. This study was financed by the Comisi6n Asesora de Investigaci6n Cientifica y Tecnica, Proyecto 3378183, Spanish Education and Science Department. References 1. Mendiola, J. M., Gonzalez, A., and Arribas, S., Afinidud, 1980,37, 39. 2. Taubinger, R. P., and Wilson, J. R., Analyst, 1965, 90, 429. 3. Analytical Methods Committee, Analyst, 1967, 92, 403. 4. Analytical Methods Committee, Analyst, 1976, 101, 62. 5. Mendiola, J. M., Gonzalez, A., and Ambas, S . , Afinidad, 1980,37,251. 6. Mendiola, J. M., and Gonzalez, A., Rev. Plast. Mod., 1981, 289, 413. 7. Mendiola, J. M., and Gonzalez, A., Rev. Plast. Mod., 1981, 299,550. 8. Anwar, J., and Marr, I. L., Talanta, 1982, 29, 869. 9. Belarra, M. A., Gallarta, F., Anzano, J. M., and Castillo, J. R., J. Anal. At. Spectrom., 1986, 1, 141. Note-Reference 9 is to Part 1 of this series. Paper J6112 Received February 28th, 1986 Accepted July 31st, 1986

ISSN:0267-9477    

DOI:10.1039/JA9870200077

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY, 1987, VOL. 2 81 COMMUNICATION Material for publication as a Communication must be on an urgent matter and be of obvious scientific importance. Rapidity of publication is enhanced if diagrams are omitted, but tables and formulae can be included. Communications receive priority and are usually published within 2-3 months of receipt. They are intended for brief descriptions of work that has progressed to a stage at which it is likely to be valuable to workers faced with similar problems. A fuller paper may be offered subsequently, if justified by later work. Manuscripts are usually examined by one referee and inclusion of a Communication is at the Editor's discretion. Oxide and Doubly Charged Ion Response of a Commercial Inductively Coupled Plasma Mass Spectrometry Instrument Alan L.Gray and John G. Williams Department of Chemistry, University of Surrey, Guildford, Surrey GU2 5XH, UK Keywords: Inductively coupled plasma mass spectrometry; MO + ions; M2+ ions; interferences Considerable interest has recently been shown in the oxide and doubly charged ion performance of the alternative plasma - mass spectrometer interfaces currently used in commercial instruments and a number of attempts have been made to draw conclusions from available data on processes occurring in these interfaces. These have, however, been hampered by the paucity of numerical data in the literature on the current performance obtained with these instruments in normal analytical use and valid performance comparisons have therefore been impracticable.The only independent data published on the VG PlasmaQuad instrument is that of Long and Brown1 and this is untypical of current practice as it was carried out on an early instrument using 0.45 mm diameter apertures. A similar report of oxide and doubly charged ion response has also been published by McLeod et a1.2 using the BGS prototype instrument fitted with 0.5 mm apertures. Both of these papers, although appearing in 1986, refer to work early in the time scale of applications development in inductively coupled plasma mass spectrometry (ICP-MS) and report results that are unrepresentative of the performance currently observed. In view of the importance of this debate to the assessment of analytical behaviour and to any resulting deductions on operating mechanisms it is considered desirable to publish a set of typical values obtained on a standard operating PlasmaQuad instrument used for analytical work in this department.Experimental The instrument used for this work was a standard VG PlasmaQuad fitted with the RFA plasma generator and torch box. This is equipped with a 3-turn load coil grounded at the torch mouth. Sampling apertures of 1 mm diameter are routinely used positioned 10 mm from the load coil, together with a skimmer of 0.7 mm diameter. Operating conditions chosen were again those used in routine analysis, power 1.3 kW, coolant flow 14 1 min-1, auxiliary flow zero and carrier gas flow 0.75 1 min-1. A Meinhard nebuliser was used in a water cooled spray chamber (13 "C) with a pumped sample uptake rate of 1.1 ml min-1.The instrument was set up exactly as it would be for routine multi-element analysis on a 1 pg ml-1 solution of Al, Co, In, Ce and Bi. The response obtained was approximately uniform across this mass range. The response was calibrated for the elements examined by running multi-element solutions as necessary at 1 pg ml-1. Oxide and doubly charged ion response was measured using solutions of 100 and 1000 pg ml-1. These of course saturated at the M+ peak but to calculate the response ratio the 1 pg ml-1 values were used extrapolated as necessary. High concentrations were used for two reasons: 1. They more closely represent the analytical situation where MO+ and M2+ responses from matrix elements cause interferences.2. Although instrument random background levels were in the range 1-5 counts s-1 some MO+ and M2+ responses had small blank peaks below them and although a blank was subtracted in each instance it was desirable to minimise blank subtraction errors as far as possible. For Cs2+ and Rb2+ the response occurred at a half mass position 66.5 and 43.5 a.m.u., respectively. Each of these partly overlaps a minor background peak, possibly from zinc memory and from 44C02+. Because of the very low value of the responses the mass analyser resolution was increased for these measurements so that these peaks at half mass unit intervals were resolved down to the base line, enabling a unique integral to be obtained for each. This resulted in a reduction of the ion transmission by a factor of two, which still left ample sensitivity for the analysis.At the carrier gas flow-rate used the mean ion energy of W o + ions was 12 eV. Results and Discussion The oxide response obtained is shown in Table 1 for 15 elements spanning a wide range of oxide bond strengths. It will be seen that the ratios MO+/M+ range from 2.8 x 10-8 to 1.3 X 10-2 and occur roughly in the same order as the bond strengths. Agreement within a factor of three is obtained with the earlier published values for the high strength oxides but for the weaker ones the values reported here are much lower. It is thought that this may indicate the formation of oxides by ion- molecule reactions within the expansion stage in the earlier work, in the same manner as ArO+ is formed. Great care is being taken in current practice to minimise these reactions so that the level of the ArO+ peak is only 10-20 ng ml-* equivalent and it is thought that this accounts for the low oxide levels seen for non-refractory species.It would not be82 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 Table 1. MO+/M+ response and oxide bond strength Bond MO+/M+ strength/ Element kJ mol-l This work Literature values Rb . . . . . . cs . . . . . . co . . . . . . Pb . . . . . . Fe . . . . . . Cr . . . . . . Al . . . . . . Ba . . . . . . P . . . . . . Mo . . . . . . Sm . . . . . . Ti . . . . . . Zr . . . . . . Ce . . . . . . Si . . . . . . 255 297 368 378 409 427 512 563 597 607 619 662 760 795 799 * Long and Brown.] t McLeod et al.2 5.5 x 10-7 - 2.8 x 10-8 1.7 x 10-5 1.2 x 10-5 1.1 x 10-3* 1.2 x 10-3t 7.1 x 10-4* 1.1 x 10-5 - 3.6 x 10-5 - 1.1 x 10-5 - 3.7 x 10-3 - 8.3 x 10-4 9.5 x 10-4 2.3 x 10-3 4.8 x 10-4* 1.8 x 10-3t 7.1 x 10-3* 1.8 x 10-3 - 4.7 x 10-3 - 1.3 X 10-2 - 1.5 x 10-3 - Table 2.M2+N+ response and ionisation energy M2+/M+ Literature Element Ei”/eV Calculated* This work valuest Ba . . . . 10.00 2.0X 10-1 4.1 X 10-2 3 . 2 ~ 10-2 Ce . . . . 10.85 5.4 X 10-2 1.4 X 10-2 Sm . . . . 11.07 3 . 8 ~ 10-2 7.9X 10-3 1.1 X 10-2 Zr 1.6 x 10-3 1.5 x 10-3 - . . . . 13.13 Ti . . . . 13.64 7.2X 10-4 6.9X 10-4 Pb . . . . 15.03 8.4 X 10-5 4.2 X 8.0 X Cs . . . . 25.08 1.5 X 10-1’ 5.5X 10-6 2.0X 10-3 Rb . . . . 27.5 3.5 x 10-13 2.4 x 10-6 - - - * Assuming Ti = 7.500 K, N, 3 X 1015 ~ m - ~ . t Long and Brown.1 ~~ ~ ~ expected that such oxides would be present in the plasma or possibly even in the boundary layer around the sampling aperture.Even refractory oxides have been found to be approximately an order of magnitude lower when samples are introduced by laser ablation without the high concentration of accompanying water from a nebulised solution, so some recombination from the dominant oxygen population seems probable for all oxides. The doubly charged ion response M2+/M+ is shown in Table 2 for eight elements of increasing second ionisation energy E;. Reasonable agreement is also found with the values of Long and Brown, except for Cs2+. Calculated values are also shown, assuming values of Ti 7500 K and N, 3 x 1015 cm-3, derived from the Saha equation, which assumes that thermal equilibrium exists in the plasma.This also assumes that no further ionisation occurs beyond the point at which Ti drops below 7 500 K. The experimental values suggest that this is not so and the Saha equation does not fit the response at all well. At the values of Ti and N , assumed, Ba and Ce appear to be less doubly ionised than would be expected and the elements of E: > 14 eV are over ionised. While using a lower value for Ti than is generally assumed would reduce the levels for Ba and Ce, it would not correct the response at the other end of the range. However, this behaviour is consistent with faster recombination occurring for M2+ ions than for M+ ions during ion extraction from the plasma, together with an additional mechanism for ionisation after extraction at a relatively low rate that does not follow the Saha relationship with E { .Several possible mechanisms can be suggested for this but the most likely seems to be that of collisional ionisation in the plasma expanding beyond the orifice, involving the small proportion (< 1%) of ions in the tail of the ion-energy distribution.3 At a mean ion energy of 12 eV, these may have energies greater than 25 eV. This would seem to account for the apparent flattening of the M2+/M+ response to a level of ca. 10-6, above E{ > 27.5 eV. Rubidium was included in the elements examined because it has the same E{ value as Ar. The level of @Ar2+ is extremely difficult to determine, in spite of the high population of @Ar+ ions, because the doubly charged ion coincides with 180H2+.This is a substantial peak in this system and cannot be calculated from 160H2+ because the latter is heavily saturated. In addition, determination of the very small 40Ar2+ peak after such a correction would be very prone to error. In a dry argon plasma with no water in the central channel only small OH2+ peaks are obtained and a better opportunity arises to measure 40Ar2+. Results from a group of runs were examined but the measured size of the 180H2+ peak was completely accounted for by that calculated from the 160H2+ response, within the level of the counting statistics on this small peak. Conclusions The levels of oxide and doubly charged ions for a representa- tive range of species are shown from measurements made on a commercial VG PlasmaQuad instrument. In terms of the analytical interferences generated by these species the oxide levels are the most significant, particularly for the lighter elements that commonly occur in the sample matrix.Elements whose bond strength lies above ca. 500 kJ mol-1 can show ratios of MO+/M+ rising from ca. 0.1% up to values of a few percent. for the most refractory species, and where these are present in the matrix it is important to be aware of this and where necessary correct for them. Fortunately their levels are found to be stable and thus lend themselves to correction from standard solutions. This re-emphasises the advantage of a survey scan of an unknown sample, before deciding which elements to select in an analytical programme. The effect of doubly charged ions on the pattern of interferences is generally less serious than that of oxides.It is most likely to be a nuisance from heavy elements as the M2+ ion occurs at half the parent mass, but except for metals and alloys these are not usually present at high levels in the matrix. One of the most serious interferences is from 138Ba2+ as Ba commonly occurs at significant levels in minerals and has the largest M2+ response, which coincides with 69Ga+. A number of similar problems can arise for other elements of low E{ where the M2+/M+ ratio is >10-4. In many instances, however, once the analyst is aware of the problem correction is straightforward.4 Interferences from elements where M2+/M+ lies below 10-4, such as 133Cs whose 2+ ion is seen between MZn+ and 67Zn+, can only arise from very high concentrations and will cause no problems at trace levels. With elements of odd mass the 2+ ion can be resolved on this instrument without unacceptable loss of sensitivity in the rare instances where it is found to be present. One of us (J.G.W.) acknowledges support from the Ministry of Defence, Procurement Executive. References 1. Long, S. E., and Brown, R. M., Analyst, 1986, 111,901. 2. McLeod, C. W., Date, A. R., and Cheung, Y. Y., Spectro- chim. Acta, Part B, 1986,41, 169. 3. Gray, A. L., Houk, R. S., and Williams, J. G., J. Anal. At. Spectrom., 1987,2, 13. 4. Date, A. R., Cheung, Y. Y., and Stuart, M. E., Spectrochirn. Acta, Part B, 1987, in the press. Paper J6l110 Received November 7th, I986

ISSN:0267-9477    

DOI:10.1039/JA9870200081

出版商:RSC    

年代:1987

数据来源: RSC

摘要:

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 83 INSTRUCTIONS TO AUTHORS The Journal of Analytical Atomic Spectrometry (JAAS) is an international journal for the publication of original research papers, short papers, communications and letters concerned with the development and analytical application of atomic spectrometric techniques. The journal is published bimonthly, and also includes comprehensive reviews on specific topics of interest to practising atomic spectroscopists and incorporates the literature reviews which were previously published in Annual Reports on Analytical Atomic Spectroscopy (ARAAS). Additional Special Conference Issues will also be published. Manuscripts intended for publication as papers or commun- ications must describe original work related to atomic spectrometric analysis.Papers on all aspects of the subject will be accepted, including fundamental studies, novel instrument developments and practical analytical applications. As well as atomic absorption, atomic emission and atomic fluorescence spectrometry, papers will be welcomed on atomic mass spectrometry and X-ray fluorescence/emission spectrometry. Papers describing the measurement of molecular species where these relate to the characterisation of sources normally used for the production of atoms, or are concerned for example with indirect methods of analyses will also be acceptable for publication. Papers describing the development and applications of hybrid techniques involving atomic spec- trometry ( e . g . , GC coupled AAS and HPLC - ICP) will be particularly welcome.Manuscripts on other subjects of direct interest to atomic spectroscopists including sample prepara- tion and dissolution and analyte pre-concentration proce- dures, as well as the statistical interpretation and use of atomic spectrometric data will also be acceptable for publication. There is no page charge for papers published in JAAS. 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Percentage concentrations of solutions should be stated in internationally recognised terms. Thus the symbols “m” for mass and “V” for volume are to be used instead of “w” for weight and “v” for volume. The following show the manner of expressing these percentages together with acceptable alterna- tives given in parentheses, where applicable: YO m/m (g per 100 g); % m/V (g per 100 ml); YO V/V. Further implications of the use of the term “mass” are that “relative atomic mass” of an element (A,) replaces atomic weight, and “relative molecular mass” of a substance (M,) replaces molecular weight. Concentrations of solutions of the common acids are often conveniently given as dilutions of the concentrated acids, such as “dilute hydrochloric acid (1 + 4) ,” which signifies 1 volume of the concentrated acid mixed with 4 volumes of water.This avoids the ambiguity of 1 : 4, which might represent either 1 + 4 or 1 + 3. Dilutions of other solutions can be expressed in a similar manner. Tables and diagrams. The number of tables should be kept to a minimum. Column headings should be brief. Tables consisting of only two columns can often be arranged horizontally. Tables must be supplied with titles and be so set out as to be understandable without reference to the text. Either tables or graphs may be used but not both for the same set of results, unless important additional information is given by so doing.The information given by a straight-line calibration graph can usually be conveyed adequately by an equation or statement in the text. The style used in headings to tables and in labels on the axes of graphs, where the numbers represent numerical values, is, for example: Volume/ml. The diagonal lines (solidus) will not be used to represent “per.” In accordance with the SI system, units such as grams per millilitre are already expressed in the form g ml-1. For a table (or graph), this would appear as: Concentration of solution/g ml-1. It should be noted that the “combined” unit, g ml-1, must not have any “intrusive” numbers. To express concentration in grams per 100 milli- litres, the word “per” will still be required: Concentrationlg per 100 ml. It may be preferable for an author to express concentrations in grams per litre (g 1-1) rather than grams per 100 ml.Most diagrams will be retraced and lettered in order to achieve uniform line thicknesses and lettering size and style, so it is not essential to prepare specially traced drawings. However, all diagrams should be carefully and clearly drawn on good quality paper and should be clearly lettered. If possible, complicated flow charts, circuit diagrams, etc., should be supplied as artwork for direct reproduction in order to avoid time-consuming and expensive redrawing. Three sets of illustrations should be provided, two sets of which may be made by any convenient copying process for transmission to the referees. All diagrams should be accompanied by a separately typed set of captions.Wherever possible, extensive identifying lettering should be placed in the caption rather than on lines on graphs, etc. Photographs. Photographs should be submitted only if they convey essential information that cannot be shown in any other way. They should be submitted as glossy or matt prints made to give the maximum detail. Colour photographs will be accepted only when a black-and-white photograph fails to show some vital feature and can be supplied either as prints or transparencies. References. References should be numbered serially in the text by means of superscript figures, e.g., Foote and Delves,’ Burns et a1.2 or Hirozawa,3 and collected in numerical order under “References” at the end of the paper. They should be listed, with the authors’ initials, in the following form (double-spaced typing) : 1.2. 3. Foote, J. W., and Delves, H. T., Analyst, 1983, 108, 492. Burns, D. T., Glockling, F., and Harriott, M., J . Chromatogr., 1980,200,305. Hirozawa, S . T., in Kolthoff, I. M., and Elving, P. J . , Editors, “Treatise on Analytical Chemistry,” Part 11, Volume 14, Wiley, New York, 1971, p. 23. Journal titles should be abbreviated according to the Chemical Abstracts Service Source Index (CASSI). The abbreviation for this journal is J . Anal. At. Spectrom. For books, the edition (if not the first), the publisher and the place and date of publication should be given, followed by the page number. Authors must, in their own interest, check their lists of references against the original papers; second-hand references are a frequent source of error.The number of references must be kept to a minimum.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 85 Appendix I The SI System of Units In the SI system there are seven base units- Some derived SI units that have special names are as follows- Physical quantity length mass time electric current thermodynamic temperature amount of substance luminous intensity Name of unit metre kilogram second ampere kelvin mole candela Examples of other derived SI units are- Physical quantity area volume density flow-rate concentration wavelength velocity magnetic field strength Symbol for unit m kg S A K mol cd Physical quantity energy force power electric charge electric potential difference electric resistance electric capacitance frequency magnetic flux density pressure (magnetic induction) Name of unit square metre cubic metre kilogram per cubic metre millilitre or litre per minute microgram or milligram per gram nanometre metre per second ampere per metre Certain units will be allowed in conjunction with the SI system, e.g.- Physical quantity volume magnetic flux density temperature, t energy (magnetic induction) Name of unit Symbol for unit Name of unit joule newton watt coulomb volt ohm farad hertz tesla pascal Symbol for unit m2 m3 kg m-3 ml min-1 or 1 min-1 pg g-1 or mg g-1 nm m s -1 A m-1 Definition of unit gauss degree Celsius electronvolt G "C eV 10-4 T tl"C= TIK - 273.16 1.6021 X 1O-IyJ Symbol for unit J N W C V D F HZ T Pa The common units of time (e.g., minute, hour, day) and the angular degree (") will continue to be used in appropriate contexts.Appendix II A b brevia t io ns Whenever suitable, elements may be referred to by their chemical symbols and compounds by their formulae. provided that they are defined at the first place of mention. Tlk following abbreviations will be used extensively in the Atomic Spectrometry Updates and may be used in original papers a.c. AA AAS AE AES AF AFS APDC ASV CMP CRM cw d.c. DCP alternating current atomic absorption atomic absorption spectrometry atomic emission atomic emission spectrometry atomic fluorescence atomic fluorescence spectrometry ammonium pyrrolidinedithiocarbamate (ammonium anodic-stripping voltammetry capacitively coupled microwave plasma certified reference material continuous wave direct current d.c. plasma tetramethylenedithiocarbamate) DMF DNA EDL EDTA ETA FAAS FAES FAFS FI GC GDL HCL h.f. HPLC IBMK N,N-dimethylformamide deoxyribonucleic acid electrodeless discharge lamp ethylenediaminetetraacetic acid electrothermal atomisation flame AAS flame AES flame AFS flow injection gas chromatography glow discharge lamp hollow-cathode lamp high-frequency high-performance liquid chromatography isobutyl methyl ketone (4-met h ylpentan-2-one)86 ICP IR LC LTE MECA MIP MS NAA NaDDC NTA PMT p.p.b. p.p.m. PTFE r.f. inductively coupled plasma infrared liquid chromatography local thermal equilibrium molecular emission cavity analysis microwave-induced plasma mass spectrometry neutron activation analysis sodium diethyldithiocarbamate nitrilotriacetic acid photomultiplier tube parts per billion (109) parts per million polytetrafluoroethylene radiofrequency JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, FEBRUARY 1987, VOL. 2 REE RM RSD SBR SEM SNR SSMS TCA TLC TOP0 u.h.f. uv VDU vuv XRF rare earth element reference material relative standard deviation signal to background ratio scanning electron microscopy signal to noise ratio spark-source mass spectrometry trichloroacetic acid thin-layer chromatography trioctylphosphine oxide ultra- high-frequency ultraviolet visual display unit vacuum ultraviolet X-ray fluorescence

ISSN:0267-9477    

DOI:10.1039/JA9870200083

出版商:RSC    

年代:1987

数据来源: RSC