JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY AUGUST 1991 VOL. 6 345 Conference Reports Third Winter Conference on Flow Injection Analysis January AZ USA 6th-9th 1991 Phoenix One of the interesting features of the flow injection techniques is that it provides common ground for analyti- cal chemists who might otherwise not consider themselves to have much in common. Thus the small group of stalwarts who braved the somewhat unseasonable coolness of Phoenix for a few days in January to attend the 3rd Winter Conference on Flow In- jection Analysis found as on previ- ous occasions that they had a lot to talk about. If it is possible to have established conference traditions at only the third attempt it would be tempting to report that the conference opened in the traditional manner with a lecture from Jarda RfiiiEka (University of Washington Seattle WA). Professor RdiiEka managed yet again to com- bine a thoughtful overview of flow analysis with some novel research from the extremely active group that he co-directs with Gary Christian.His unfailing enthusiasm for the pos- sibilities of flow analysis is hard to resist and his view that flow injection (FI) provides the interface between solution chemistry and instrumenta- tion surely identifies a major direc- tion for the development of analytical chemistry. A direction not just for research with the consequent impli- cations for the practice of analytical chemistry but intriguingly also a direction for the teaching of analyti- cal chemistry. Maybe the time is right for the replacement of the ‘quant’ and ‘instrumental’ courses (typically taught in US institutes of higher education) by courses that teach ana- lytical chemistry through the medium of flow techniques.The recent devel- opments in the field of FI for atomic spectrometry culminating in the appearance of the FIAS 200 unit from Perkin-Elmer were cited as a good example of how FI techniques provided such an interface. Sequential injection and ‘sinusoi- dal flow’ were also discussed to the delight of those practitioners who always maintained that FI would only achieve its true potential once the present rotary injection valve and peristaltic pump were replaced by more reliable components. The use of a stream switching valve to sequenti- ally aspirate wash sample and reag- ent solutions by the withdrawal of the plunger in a syringe pump represents a new concept in that the resulting FI peak produced on reversal of the plunger direction results from the interdispersion of sample and reagent at just a single boundary (conven- tional FI peaks are formed by the overlap of front and rear boundaries of the injected sample) under the hydrodynamic regimes produced by the variable flow of the piston pump.The theme of reliability of compo- nents was continued in subsequent talks concerned with process analysis and control. Duane Wolcott (Dow Chemicals Plaquemine LA) pre- sented results obtained with a versa- tile propulsion unit constructed from a number of FMI pump heads driven from a single stepper motor. A num- ber of operations could be imple- mented including on-line dilution and liquid-liquid extraction by vary- ing the volume per stroke and run- ning the pumps either in or out of phase.With up to 800 steps per stroke of the pump head precise control over fluid metering was pos- sible. Don Olson (Shell Develop- ment Houston TX) described his organization’s approach in develop- ing a ‘generic’ process analyser based on FI methodology. The versatility of the technique in the laboratory situa- tion was illustrated by the design of a manifold for the determination of five sulphur species in aqueous samples. The benefits of the reverse configu- ration (in which the sample is the carrier stream) were nicely illustrated by Ernie Boughman (Amoco Naper- ville IL) who described a process analysis system in which the pressure in the sample line was used for propulsion.The reagent was also de- livered from pressurized reservoirs and injected via a 1 0-port slider valve to produce two reagent zones with a sample zone trapped in between. Mixing was assisted by the use of a helical insert. The session on FI ap- plications to process streams finished with Karl Schick’s (FIAtron-Eppen- dorf Madison WI) description of a system for the determination of H2S and C02 based on gas-phase molecu- lar absorption. After liberation of the gases by the addition of acid HIS is determined by UV absorption and C02 by IR absorption. In addition a total alkalinity parameter could be determined via the enthalpy of neu- tralization measured with a thermis- tor detector. An indication of the maturity of FI methodology and of the impact on standard methods was provided by Scott Steig (Lachat Instruments Milwaukee WI) who described the work of a Joint Task Group of the Joint Editorial Board of Standard Methods for the Examination of Water and Wastewater to create a new section entitled ‘Automatic Continuous Flow Analysis’.He dis- cussed the difficulties that had arisen as a result of the writing of methods around the characteristics of one par- ticular manufacturer’s instrumenta- tion and proposed a set of generic manifold diagrams for the ‘big eight determinations of environmental lab- oratories’ (chloride fluoride ammo- nia total oxidized nitrogen nitrite phosphate silicate and sulphate). It was pointed out that The Environ- mental Protection Agency has already approved FI as an option in continu- ous-flow methodology.A critical examination of one of the fundamental differences between the two types of methodology was then made by Charles Patton (US Geologi- cal Survey Arvada CO) who pointed out that it was possible to obtain reproducible timing in a gas-seg- mented stream. This can be achieved by the use of the so-called air-bar technique (adding air bubbles to the analytical stream in phase with the roller lift-off). This technique can be adapted to FI to give a gas-segmented reactor which has mixing character- istics that are superior to the open tubular reactor and allows an en- hanced sample throughput to be achieved. Could the bubble be poised for a ‘come-back’? In the pursuit of improved detec- tion limits Dave Curran (University of Massachusetts Amherst MA) elec- trified his audience with the perf‘orm- ance of a simple cross correlation technique.A single-line manifold was used in which a reference signal was first generated with a high concentra- tion of analyte. This signal was stored and played back in real time synchro- nized with the analyte signal. The cross correlation (essentially multipli- cation and time averaging) produced a reduced sensitivity but this was offset by the noise reduction to such an extent that well over an order of346 magnitude improvement in the detec- tion limit for the amperometric determination of dopamine was obtained. There would seem to be no reason why this technique could not be applied to other types of detector. Another aspect of the use of com- puters in the pursuit of improved analytical performance was provided by Terry Tougas (Polaroid Waltham MA). A multi-component spectro- photometric procedure had been fully automated including the production and display of control charts and transfer of the results to VAX-based corporate databases.The need for automation in the provision of ana- lytical information in support of the running of a nuclear power station was illustrated by Mike Whitaker (Westinghouse Savannah River Com- pany Aiken SC) who described an approach to the measurement of pH in unbuffered solutions. A spectro- photometric procedure based on the indicator Resazurin has achieved precisions of less than 1% RSD over the pH range 4.7-5.3. The first day concluded with a description by Steve Hoke (US Army Biomedical Research and Develop- ment Laboratory Frederick MD) of a field instrument for monitoring the concentration of potentially toxic gases.Such gases are emitted not only by various incinerators and electrical fires but also by various military weapons. A rapid extraction system based on a continuous impinger had been interfaced with an FI system with potentiometric detection to give near real-time response for a number of constituents. The extent to which FI procedures are now part of analytical atomic spectrometry was reviewed by Julian Tyson (University of Massachusetts Amherst MA) in the first lecture of the next session. In particular the use of solid-phase reagents for analyte preconcentration and matrix removal has attracted considerable interest and a substantial number of publica- tions (over 60) have appeared that deal with such procedures.Dr. Tyson also outlined recent work in his own research group concerned with (a) matrix removal for hydride genera- tion by using a solid-phase reagent; (b) the use of a supercritical fluid carrier stream; and (c) the on-line digestion of the organic matrix of a slurry sample. A number of FI atomic spectrome- try topics were covered in more detail in the following papers. The problems of determining tin by hydride genera- tion procedures were discussed by Randy Hergenreder (Perkin-Elmer Norwalk CT). It was shown that JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY AUGUST 1991 VOL. 6 most of the problems arose from the presence of other hydride forming elements in the sample matrix when a heated quartz tube atomizer was used.A considerable improvement in performance was obtained when the generated hydride was collected in a graphite furnace that had been pre- treated by the injection of a solution of palladium. A characteristic con- centration similar to that obtained for direct introduction of an aqueous tin standard into the furnace was obtained. This procedure could well become the standard method of de- termining hydride forming elements. The topic of chemical vapour gen- eration was continued in the presen- tation by Ed Paxki (Bondar-Clegg North Vancouver British Columbia) who entertained his audience with an account of how a laboratory faced with the requirement to analyse large numbers of mineral samples for mer- cury had developed an automated FI cold vapour atomic absorption spec- trometer.The instrument could handle between 1000 and 1500 deter- minations per 24 hour day once a sample solution had been obtained. A dynamic range of between 0.5 and 5000 pg I-’ was obtained for a 200 pl sample solution. The problems that a laboratory of this sort faces were nicely illustrated by the disastrous effects of the atternpted analysis of a sample with an unexpectedly high gold content. The appearance of a purple coating of colloidal gold on the interior of the flow lines heralded an extended shut-down and some equally colourful language to describe Dr. Paski’s feelings about his secre- tive client. There are good commer- cial reasons for not disclosing the full details of the instrument’s construc- tion and operation which means unfortunately that the results of another first-rate piece of research in instrumental analytical spectroche- mistry will not find their way into the open literature.The on-line derivatization and ma- trix isolation theme was continued with a description by Herb Lancaster (University of Washington Seattle) of a sorbent extraction system coup- led to a flame atomic absorption spectrometer. In this procedure a chelating agent is first sorbed onto a solid reversed-phase chromatography stationary phase (typically CI8 ma- terial). The sample solution was then passed and the analyte species re- tained by the modified solid-phase reagent. Elution was effected by changing the polarity of the solvent and reversing the direction of fluid flow.It was pointed out that the design of manifolds for solid-phase extraction was often limited by a ‘legacy from chromatography’ namely that the system should con- tain a fully-packed column and use unidirectional flow. However by re- ducing the amount of solid phase in the column a kind of ‘fluid-bed’ was produced which although increasing the dispersion coefficient slightly avoided the problems of flow reduc- tion which often occur in this type of manifold as the back-pressure due to the column gradually increases with use. The versatility of FI procedures was illustrated by Elo Hansen (Tech- nical University Lyngby) who de- scribed an amplification procedure based on the use of co-immobilized enzymes. The manifold was concep- tually similar to that described for the preconcentration of trace elements for detection in atomic spectrometry but the chemistry was tailored to the determination of traces of pyruvate or lactate.The enzyme reactor con- tained both lactate oxidase and lac- tate dehydrogenase so that the pro- duct of an enzyme catalysed reaction was a substrate for the second system which regenerated the reactant. In the particular system chosen the contin- uous cycle produced a considerable excess of the co-product hydrogen peroxide which was detected by the chemiluminescence generated from the oxidation of luminol (catalysed by Fe*I1). Amplification factors of be- tween 100 and 1 50 were possible. The importance of enzymes and the need to monitor inhibitors was brought into sharp focus by Jim Hungerford (US Food and Drug Administration Bothell WA) who described the symptoms of Scombroid poisoning a reasonably common problem arising from the improper storage of certain foods especially cheese and fish.Vic- tims show typical allergic reaction symptoms due to disruption of con- trol mechanisms for the regulation of the histamine levels throughout the body. Diamine oxidase is one of the enzymes involved and an assay for possible toxic effects was constructed around the interruption by sample components of the steady-state en- zymic destruction of histamine. Fluo- rescence detection was used to moni- tor the reaction product between his- tamine and phthalaldehyde. Fluorescence detection was also used in the system described by Tho- mas Gubeli (University of Washing- ton Seattle) for the kinetic determi- nation of a proteolytic enzyme widely used in the detergent industry.The sinusoidal flow and sequential injec- tion procedures described earlier by Jarda REiiEka were used as the basis for a fully automated stopped-flow method. The substrate used was aJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY AUGUST 1991 VOL. 6 347 tripeptide containing 7-amino-4- methyl coumarin which when re- leased by the enzyme reaction had a fluorescence intensity 850 times that of the tripeptide. The claim of luminescence to be a detection mode ideally suited to flow injection presentation is only beaten by that of electrochemical procedures which are undoubtedly enjoying a new lease of life thanks to flow injection.The use of a nickel oxide potentiometric electrode for the de- tection of alcohols amino acids and carbohydrates was described by Cal- vin Huber (University of Wisconsin Milwaukee WI) who stated that FI provided an ideal method of control- ling the electrode environment dur- ing the pre-treatment stage. The sur- prising versatility of biologically modified electrodes was illustrated by the quick-fire presentation of numer- ous examples by Joe Wang (New Mexico State University Las Cruces NM) who has continued to raid the fruit and vegetable world for enzyme- containing tissue with which to fabri- cate electrodes. In this chapter of what is a fascinating and continuing story bananas potatoes papaya and zuccini made an appearance some- times in intimate contact with the electrode material (as with the bana- na-carbon paste electrode for the determination of dopamine) and sometimes as an upstream bioreactor (mounted in the tube wall) with downstream amperometric detection.The final day of the conference opened with an overview from Elo Hansen of whether FI is exploited optimally. With the FI literature standing at some 3300 publications in 1990 it was clear that many uses of FI centered on the potential for the development of automated chemical analysis procedures. However Dr. Hansen agreed that the real power of FI lies in the unique possibilities of the methodology which go beyond the development of continuous flow versions of previously devised batch chemical procedures. A number of examples of the unique FI features several of which involved atomic spectrometry were cited in support of this thesis.These included (a) the ability of an FI sample introduction system for flame and plasma based techniques to deliver samples with high dissolved solids or with high organic solvent contents; (b) the pos- sibility for time-based measurements such as peak width or gradient dilu- tion; and (c) the implementation of various indirect procedures. In addi- tion to the atomic spectrometry pos- sibilities features concerned with ki- netic characteristics such as kinetic marking kinetic discrimination at electrode and other sensor surfaces and stopped flow were discussed. The ability of an FI system to synthe- size reagents (possibly unstable ones) when needed was also discussed. It would seem there are still some un- derexploited areas and perhaps even some as yet undiscovered possibili- ties for FI.The discussions took a more practi- cal turn following the presentation by Gil Pacey (Miami University Ox- ford OH) concerning a new device for producing mixing at confluence points. This discussion suggested that there is still some difficulty in visualizing the scale of the longitudi- nal and radial gradients. Maybe flow injection should be demonstrated on more occasions (see Tyson J. F. Fresenius 2. Anal. Chem. 1987,329 675). A good example of the exploitation of the kinetic character of FI was provided by Mike Straka (Perstorp Analytical Herndon VA) who de- scribed a method for the determina- tion of total cyanide. Gas diffusion was first used (an illustration of the safe sample handling environment provided by an FI manifold) to sepa- rate the analyte which was then quan- tified by measurement of an unstable intermediate instead of the stable final product of the reaction between cyanide isonicotine acid and 3-me- thyl- 1 -phenyl-5-pyrazolone. As the full formation of the product is rela- tively slow the throughput was in- creased when the intermediate was monitored.Further utilization of the precise kinetic nature of fluid flow was provided by Richard Taylor (University of Washington Seattle WA) who presented results for the flow injection coulometric titration of acids and bases over 3-4 orders of magnitude of concentration. The wide working range was achieved by on-line dilution in a well-stirred tank.End-point detection was by remote spectrophotometry with fibre-optic light guides. The dilution chamber titrant generation chamber and detec- tor flow cell were integrated into one unit. Precisions of between 1 and 3% RSD were obtained. In the final presentation Adrian Wade (University of British Colum- bia Vancouver) presented results for the automated optimization of a spectrophotometric method for the determination of sulphide. The diffi- culties that an automated simplex optimization procedure could en- counter were nicely illustrated and the importance of not neglecting some basic chemistry stressed. The full range of the factor space for reagent concentrations including a region in which a precipitate formed which not unnaturally gave very high absorbance readings.The prob- lem was recognized by constructing a response surface map from a 7x7 experimental grid. The procedure eventually developed was applied to the analysis of wood pulp liquors. In addition to the formal presenta- tions and discussion the excellent venue chosen by the organizers (and the somewhat atypical inclement weather) ensured that there was plenty of opportunity for informal discussion among delegates as well as an opportunity to view equipment in a small exhibition mounted by Per- kin-Elmer Lachat and FIAtron- Eppendorf. One outcome of this dis- cussion was that the fourth Winter Conference on Flow Injection Analy- sis will take place in 1992. To accom- modate the burgeoning interest in the flow injection-atomic spectrometry combination the meeting will be held on January 12th- 14th immediately following the 1992 Winter Confer- ence on Plasma Spectrochemistry (to be held in San Diego January 6th-11 th 1992) although the venue will again be Phoenix.Julian F. Tyson University of Massachusetts Amherst MA USA348 JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY AUGUST 199 1 VOL. 6 Atomic Spectrometry Updates Editorial Board Meeting and Scientific Symposium March 27th-28thY 1991 Polytechnic South West Plymouth UK For those of us lucky enough to arrive on the evening prior to the meeting the proceedings could not have begun in a better fashion than the splendid meal to which we were treated at a Spanish restaurant in Plymouth’s his- toric Barbican area. When Neil Bar- nett was in Plymouth this was one of his favourite haunts one can only speculate about the dive in profits they must have suffered since his departure to Melbourne! The main business of the first day was the 25th meeting of the ASU (formerly ARAAS) Editorial Board.Discussions principally concentrated on reports from the executive mem- bers and reports from the six review group co-ordinators with special praise bestowed upon Steve Hill and David Littlejohn for the success of their groups in establishing the two new reviews covering firstly atomic emission and secondly atomic ab- sorption and fluorescence. Some con- cern was voiced over the sheer vol- ume of abstracts now being covered but if the reviews are to be thorough it is difficult to see how this can be avoided. One suggestion was to be more selective about the inclusion of conference abstracts particularly as there is often many a slip ‘twixt abstract and paper’.The day culminated in a hazard- ous journey across the waters to Cornwall and a sumptuous Board Dinner held in a converted coastal fort overlooking the entrance to the English Channel. Entertain- ment was provided by John Price who gave an amusing overview of the first 25 years of ARAAS/ASU. Retirement awards were given to Alan Ure David Littlejohn and Les Ebdon. The scientific symposium was en- titled ‘Alternative Plasma Sources’ and began with a fascinating lecture by Ramon Barnes on the develop- ment of the microwave-induced plasma which has led to the recent introduction of a commercial GC- MIP an instrument that has the considerable attraction of being ap- plicable to the analysis of non-metals.The second part of Professor Barnes’ talk concentrated on a new ICP confi- guration i.e. the sealed ICP. In this the discharge is sealed in a closed quartz container; such a design en- hanced sensitivity over the normal flowing gas ICP. The second presentation by John Dean was of an elegantly designed glow discharge cell which was mounted in the burner compartment of an atomic absorption spectro- meter. The device is being applied to the determination of nickel in steels. There then followed a review from David Littlejohn of progress at Strathclyde and elsewhere in FANES. Although problems exist particularly with calibration where internal standards often have to be used the potential of the technique was apparent particularly for the determination of non-metals.Cur- rent detection limits for FANES lie between those for ETAAS and ICP- AES. Two entertaining talks either side of lunch from Janet Armstrong and Mike Thompson concentrated on two of the more popular plasma sources the DCP and the ICP. Janet gave an overview of environmental analysis using DCP whilst Mike Thompson re-defined the calendar in outlining how the ICP has got to where it is now. The second overseas speaker was Jean-Michel Mermet who in his inim- itable style once again gave us plenty of food for thought this time on the subject of laser produced plasmas an idea first postulated in 1962. How- ever progress has been slow and development is still at the early stage. Nonetheless the technique promises local analysis of solid samples at very competitive detection limits. The uti- lization of fibre-optics makes on-line detection feasible. In the caboose was the third over- seas speaker Ben Fairman from Oveido University. Going by the aerial ballet performed by a number of his slides Ben must have upset the god of conference projectors. Despite major difficulties he persevered with his presentation of sample introduc- tion phenomena using DCP. Select- ing kaolin slurries as samples he used computerized tomography to map spatially the plasma and identify areas of maximum emission. In conclusion one must congratu- late Steve Hill and the staff in Plym- outh for their successful organization of the meeting a success which bodes well for the 6th BNAAS meeting in 1992 for which Polytechnic South West is also the venue. Simon Branch Rank Hovis MacDougalr‘ Research and Engineering Ltd. The Lord Rank Research Centre Lincoln Road High Wycombe Buckinghamshire UK