Anal. Chem. 1988, 60 342 13-360 R I
(Q206) Mikami, N.; Wakaboyashi, N.; Yamada, H.; Miyamoto, J. Pestic. Sci. 1985, 76,46-58. (Q207) Stout, S. J. I n Applications of New Msss Spectrometry Techniques h PestlcMe Chemistry: Rosen, J. D., Ed.; Wiley: New York, 1987; pp 9-21. ((2208) Sirnoneaux, B. J.; Marco, G. J. I n Applications of New Mass Spectrometry Techniques in PesticMe Chemistry; Rosen, J. D., Ed.: Wiley: New York, 1987; pp 222-246. (Q209) Kriemler. P.; Muecke, W. I n Applications of New Mass Spectrometry Technlques in PesticMe Chemistry; Rosen, J. D., Ed.; Wiiey: New York, 1987; pp 116-127. (4210) King, G. S.; Heath, J.; Runnalls, N.; Hammond, I. Presented at the 35th Annual Conference on Mass Spectrometry and Allied Topics, Denver, CO, 1987; pp 440-441. (Q211) Rosen, R. T.: Rosen, J. D. Biomed. Mass Spectrom. 1982, 9 , 443-449. (Q212) Mirocha, C. J.; Pawiosky, R. A.; Chatterjee, K.; Watson, S.; Hayes, W. J. Assoc. Off. Anal. Chem. 1983, 66, 1495-1499. (Q213) Pare, J. R.; Greenhaigh, R.; Lafontaine, P.; Apsimon, J. W. Anal Chem. 1985, 57, 1470-1472. (0214) Lauren, D. R.; Ashley, A.; Biackweii, B. A.; Greenhalgh, R.; Miller, J. D.;Nelsh. G. A. J. Agric. Food Chem. 1988. 3 6 , In press. (Q215) Lauren, D. R.: Di Menna, M. E.; Qreenhalgh, R.; Miller, J. D.; Neish, G. A.; Burgess, L. W. NZ J. Agric. Res., in press. (Q216) D’Agostino, P. A.: Provost, L. R.; Drover, D.R. J. Chromatogr. 1986, 367, 77-86. (Q217) Miles, W. F.; Gurprasad, N. P. Biomed. Mass Spectrom. 1985. 72, 652-658. (Q218) Brumiey, E. C.; Trucksess, M. W.; Adler, S. H.; Cohen, C. K.; White, K. D.; Sphon, J. A. J. Agric. FoodChem. 1985, 3 3 , 326-330. (Q219) Gilbert, J.; Startin, J. R.; Crews, C. J. Chromatogr. 1988, 368, 376-381. (Q220) Kientz, C. E.; Verweij, A. J. Chromatogr. 1986, 368, 229-240. (4221) Rizzo. A. F.; Saari, L.; Lindfors, E. J. Chromatogr. 1988, 368, 381-386. (4222) Holland, P. T.: McGhie, T. K.; Laureq, D. R., submitted for publication in J . Chromatogr. (Q223) Karppanen, E.; Rizzo, A.; Berg, S.; Lindfors, E.; Aho, R. J. Agric. Sci. Finland 1085, 5 7 , 195-208. (Q224) Hewetson, D. W.; Mirocha, C. J. J. Assoc. Off. Anal. Chem. 1987, 70, 647.
(Q225) Krishnamurthy, T.; Wasserman, M. 8.; Sarver, E. W. Biomed. Environ. Mass Spectrom. 1988, 73, 503-518. (Q228) Black, R. M.; Clarke, R. J.; Read, R. W. J. Chromatogr. 1988, 367, 103-1 15. (0227) Begley, P.; Foulger, B. E.; Jeffery, P. D.; Black, R. M.; Read, R. W. J. Chromatogr. 1986, 367, 87-101. ((2228) Black, R. M.; Clarke, R. J.; Read, R. W. J. Chromatogr. 1987, 388, 365-378. (Q229) Krishnamurthy, T.; Sarver, E. W. J. Chromatogr. 1986, 355, 253-264. (Q230) Kalinoski, H. T.; Udseth, H. R.; Wright, 6. W.; Smith, R. D. Anal. Chem. 1986, 58, 2421-2425. (Q231) Krishnamurthy, T.; Sarver, E. W.; Greene, S. L.; Jarris. B. B. J. AsSOC. Off. Anal. Chem. 1987, 7 0 , 132-140. (Q231a) Rood, H. D.; Buck, W. B.; Swanson, S. P. J. Agric. Food Chem. 1988, 3 6 , 74-79. ((2232) Rosen, J. D.; Rosen, R. T.; Hartman, T. G. J. Chromatogr. 1988, 355, 241-251. (0233) Krishnamurthy, T.; Sarver, E. W. Anal. Chem. 1987, 5 9 , 1272-1278. ((2234) Krishnamurthy, T.; Sarver, E. W. Biomed. Environ. Mass Spectrom ., in press. (Q235) Rajakyia, E.; Laasasenaho, K.; Sakkers, P. J. D. J. Chromarogr. 1987. 384, 391-402. (0236) Tieback, R.; Blaas, W.; Kellert, M.; Steinmeyer, S.; Weber, R. J. Chromatogr. 1985, 318, 103-111. (Q237) Visconti, A.; Treeful, L. M.; Mirocha, C. J. Biomed. Mass Spectrom. 1985, 72, 689. (Q238) Chatterjee, K.; Visconti, A.; Mirocha, C. J. J. Agric. Food Chem. 1986, 3 4 , 695-697. (Q239) Swanson, S . P.; Nicoletti, J.; Rood, H. D.; Buck, W. B.; Cote, L. M.; Yoshizawa, T. J. Chromatogr. 1987, 4 14, 335-342. ((2240) Sakamoto, T.; Swanson. S.P.; Yoshizawa, T.; Buck, W. B. J. Agric. Food Chem 1986, 3 4 , 458-460. ((2241) Cote, L.-M.; Nicoletti, J.; Swanson, S. P.; Buck, W. B. J. Agric. Food Chem. 1986, 3 4 , 458-460. ((2242) Yoshizawa, T.; Cote, L.M.; Swanson, S. P.; Buck, W. 8. Agric. Biol. Chem. 1986, 50, 227-229. (Q243) Voyksner, R. D.; Hagier, W. M.; Swanson, S. P. J. Chromatogr. 1987, 394, 183-199.
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Emission Spectrometry Peter N. Keliher,*>’Daniel J. Gerth, John L. Snyder, Muanan Wang,Zand S u e F. Zhu Chemistry Department, Villanova University, Villanova, Pennsylvania 19085 This is the 21st article in the series of biennial reviews in the field of emission spectrometry/spectroscopy and is the fifth written by the Villanova University author group (AlA4). This year Daniel J. Gerth and Human Wang join us as coauthors replacing Walter J. Boyko and Robert H. Clifford who assisted with the last review. This review article will survey selectively the emission spectrochemical literature of 1986 and 1987. By agreement, however, flame emission publications are reviewed in the section of this review issue entitled “Atomic Absorption, Atomic Fluorescence, and Flame Spectrometry” authored by James A. Holcombe and Dean A. Bass of the University of Texas at Austin (A5). This follows previous custom. Because of the late arrival of some journals appearing in December 1987, we may have missed some references of importance, and it is hoped that these will be discussed in the next biennial review. In general, we are following the format that we have used in our previous reviews (Al-A4). One important change, however, must be noted here. We have been citing important inductively coupled plasma mass spectrometry (ICP-MS) papers in recent reviews even though they are not (technically) emission spectrometry papers. Our reasons for citing these papers have been noted in previous reviews. In our most recent review, we noted in tabular form the explosive growth of the ICP-MS technique. This trend is even more noticeable Reprints of this review are available on request. *Presentaddress: Harbin Institute of Technology, Harbin, Peo-
ple’s Republic of China. 342 R
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now than it was two years ago. For that reason, Analytical Chemistry begins a new review in this issue entitled “Atomic Mass Spectrometry”. This new review, authored by David W. Koppenall of the University of Texas at Austin will include ICP-MS papers (A6). In this emission spectrometry review, therefore, we will not cite ICP-MS papers unless they are part of work comparing ICP-MS with optical techniques. Because of space considerations, we have had to be particularly selective in this review and we have not attempted to provide an all-inclusive bibliography. In this fundamental review, the emphasis will be on developments in theory, methodology, and instrumentation. Applications will be cited only insofar as they advance the state of the art or have particular current relevance. References are cited only if they are of particular importance to analytical chemists and spectroscopists; articles of primary interest to astronomers and/or physicists are not, in general (with some exceptions in section B), cited. Readers should note that detailed and specific application information is available from Analytical Abstracts, Chemical Abstracts, and also the more specific Atomic Absorption and Emission Spectrometry Abstracts published by the PRM Science and Technology Agency ( A n . In addition, the latest Application Reviews issue of Analytical Chemistry contains many recent spectrochemical application references (A@. Readers should also note that the Journal of Analytical Atomic Spectrometry (JAAS)contains a section entitled “Atomic spectrometry Updates” (ASU) which is, in fact, the new format of what had been called the Annual Reports on Analytical Atomic S ectroecopy (ARAAS) published by the Royal Society of Cfemistry. Typical ASU up@ 1900 American Chemical Society
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Paw N. K . l h n b kdessw 01 A n a w l
Chemisby at Villanwa Univsreiiy. He received hi8 AB. degree (1962) hom SI. MIchael's college and M.Sc. (1987) and R.D. (1969) W e s s from Universny 01 London. Prolessor Keliher also M I me D l p l ~ ma 01 Mambership (D.1.C.) 01 Imperial CoC l e p . ck. Kellher came to Villanova in 1969 :0' * he was promoted lo A s ~ ~ ~ lProlessor ale In 1974 and lo Prolessor in 1979. He has published approximately 85 papers in "ark ow areas of analytical chemistry wim an emphasis On ~ p e ~ l r ~ m methods. sbl~ He Division 01 Anaserved as Treasurer 01 lytical Chemistry (ACS) from 1978 through 1982 and he is presenHy an Anernate Councilor for the Dlvl~ion. He was Chakman of the Fedemtbn 01 Analytical Chsmbtry and Specmascopy Sac& lies (FACSS) Governing Board in 1979 and w e d as FACSS Exhibn Dlrectw h m 1981 through 1985. He was A ~ ~ i ~ l Program ant Chairman lw me 1986 Eastern Analytical Symposium (EAS) and 1987 EAS Program Chairman. Professor Keliher is also Ednor of me MicrochemicalJournal. the official OublIcation 01 the American Microchemical Society.
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Duw J. Oru, I8 -,king tmard th R D . Wee a1 Villanova u& d b c l b n 01 Prole094 Usliner He received his B S db aree 119741 from Western lilinob Univh.siN. kcimb. A I I ~ ~SBYBIBI yean 01 ind& trial experience. he received M.S. degree t r m vlllanova in 1987 He is presently employed by Bet2 Laboralorles where he is me inorganlc anaMica laboratory supam+ a.HISlnleresls are wlde ranging lncludlng ion chromatography. flow inkction anawrls. sample introduction techniques. microcomputer appllcatians In chemistry. and chemomelrlcs.
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ProleKeIiIWlr. He received his B.A. degree (1975) from Masslah College. Oranthan. PA. He men spent several yeam leaching chemistry and physics in Zambia and Zimbabwe. He received his M.S. degree horn VIhnwa in 1985 and is presenHy employed at Lanc~slerLabaatorias. Inc.. In Lancaster. PA. His Chemical interests include atomic absorption specbophotomeby. plasma emkdon opectromatry. gas chanatography. ion chromatography. and new methods lor ms determlnalio" Of halogens.
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dates include reports on environmental analysis (As), instrumentation (AIO), atomization and excitation ( A l l ) , and minerals and refractories (Al2). The last two years have shown clearly that JAAS incorporating ASU is a very worthy successor to ARAAS. The editor, Judith Egan. is commended for her outstandingefforts. For information on the philosophy of JAAS. the reader should consult the special February 1986 issue of Chemistry in Britain (Al3) and, in particular, the article on JAAS written by the late John M. Ottaway (Al4). Professor Ottaway had been Chairman of the JAAS Editorial Board and his untimely passing away a t the young age of 47 is of deep regret to the entire analytical chemistry community. In going through the 19861987 literature, we have seleded the following publications as being most relevant and most emission spectrometry papers published in these journals are cited in this review: Analyst (London), Analytica Chimica Acta, Analytical Chemistry, Analytical Letters, Applied Optics, Applied Spectroscopy, Applied Spectroscopy Reviews. Atomic Spectroscopy, Canadian Journal of Spectroscopy, CRC Critical Reviews in Analytical Chemistry, Enuironmental Science and Technology, Fresenius' Zeitschrift fur Analytische Chemie, ICP Information Newsletter, International Journal of Environmental Analytical Chemistry, JAAS, Journal of Chemical Education, Journal of the Optical Society of America, Journal of Quantitative Spectroscopy and Radiative Transfer, Microchemical Journal, Optica Acta, Progress in Analytical Spectroscopy, Reviews in Analytical Chemistry, Review of Scientific Instruments, Science, Spectrochimica Acta, Part E, Spectroscopy Letters, Talanta, and Water Research. Papers published in unreviewed magazines such as Americanllnternational Laboratory, Laboratory Practice, Research and Development, Spectroscopy, etc. are not generally cited. However, where we feel that a publication is of fundamental importance, it is cited whatever the source. 1988 Notes: As stated previously, JAAS has become a MAJOR new journal that should be read by all workers in the field of emission spectrometry. The ICP Information Newsletter (edited by Ramon M. Barnes)continues to he the "club" newsletter containing important information on current trends in atomic spectrometry as well as abstracts of atomic spectrometry papers presented a t major national and international meetings. No emission spectrometry lahoratory should he without this important newsletter!!! We note, sadly, the retirement of Josephine M. Petruzzi in 1987 BS Executive Editor of Analytical Chemistry. We concur with the editor ( A X ) with respect to her valuable service and we wish her well in her retirement.
BOOKS AND REVIEWS In our last review (A4), we took the unusual step of citing
1 -.
horn the Government 61 the People's R e p ~ l i cot China and thls aliowed hlm lo spend a lull year (1987) in Rolessm UsU her's iaboratorv. DurlnO his time at VlllanP
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mar wnh an emphasis on the development 01 improved techniques lor sample inbcduc-
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8u F. Zhu Is presenlly UmpIeUng her R.D. Umsis research w& u& d1re.p lion 01 ProleMor Keliher. She received her B.S. degree (1982) and her M.S. degee (1985) lrom Jllln Univ-ny. Changchun. ,, . People's Republic of Chlna. She began her ~, ' graduate otudleo at Villanova h Ihe autumn of 1985. Her thesis w a k is concerned with lmpravements in plasma emission Spectrometry with an emphasis on Inductively coupled plasma atomic fiuoresCenCe specbometry. Her l n t e r e ~also l ~ include the role of mmputers in chemlstry. *L.c Ms. u l u has recently received a Gordon F. 4 Kirkbright travel grant horn me AsSOCialhn 01 Brilish Specboscoplsls. This will allow IWlr lo anend the 41h BNASS conlerence at lhe UnlversHy 01 York. U.K.
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a book that had not, as of that time, been published, We did this because we felt that Inductively Coupled Plasmas in Analytical Spectrometry, edited by Akbar Montaser (George Washington University) and Danold W. Golightly (US. Geological Survey. Reston, VA) would become a very important book. Well, we were right!!! This book, which was published in early 1987 (A16), contains 16 extremely well written chapters on all important aspects of ICPs. In addition, there is a well written Foreword by Velmer A. Fassel, one of the fathers of the ICP. In the book's beginning chapter, Montaser and Golightly discuas the significance of ICPs relative to other plasmas. Miller (Johns Hopkins University) discusses basic concepts in atomic emission spectrometry (AES), Strasheim (University of Pretoria, South Africa) reports on instrumental requirements, Greenfield (Loughborough University of Technology) provides information on common rf generators, torches, and sample introduction systems, Thompson (Imperial College), discusses the analytical performance of ICPAES, Edelson (Ames Laboratory, Iowa) reports on high-resolution plasma spectrometry, and Hasegawa and Haraguchi (University of Tokyo) discuss some fundamental properties of ICPs. In part I1 of the book, Omenetto (European Community Center, Ispra, Italy) and Winefordner (University of Florida) report on atomic fluorescence spectrometry (AFS) in the ICP and Horlick and coworkers (University of Alberta, Canada) report on the latest developments in ICP-MS. In part I11 of this marvelous book, Gustavsson (Royal Institute of Technology, Sweden) discusses lipid sample introduction into plasmas and Routh and Tikkanen (ARL, Sunland, CA) ANALYTICAL CHEMISTRY, VOL. 80, NO. 12. JUNE 15. 1988
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comment on some difficulties associated with the introduction of solids into plasmas. Following this chapter, Caruso (University of Cincinnati) and co-workers report on the injection of gaseous samples into plasmas. deGalan and van der Plas (Technical University of Delft, Netherlands) discuss low-gas-flow torches for the ICP and Ohls (Hoesch Stahl AG, Dortmund, West Germany), Golightly, and Montaser have an extremely well written chapter on mixed-gas, molecular-gas, and helium ICPs operated at atmospheric and reduced pressures. The book concludes with a chapter by Keliher (Villanova University) givin an “overview” of analysis by ICP-AES. This book is H I J H L Y RECOMMENDED. Another extremely important book published in 1987 is the two-volume Inductively Coupled Plasma Emission Spectroscopy edited by P. W. J. M. Boumans. Part I of this book (A17‘) covers the basis of ICP-AES as an analytical method and discusses fundamental analytical concepts, performance, and figures of merit; principles of the instrumentation; and the relationship between the ICP and other lasma sources with some comments on ICP-AFS and ICP-Mi The majority of part I was written by Boumans. There are nine chapters in part I. Part I1 (A18) of the book contains several applications chapters for various materials such as metals and industrial materials, geological, environmental, agriculture and food, biological-clinical, and organics. There is also a chapter on the direct elemental analysis of solids by ICP-AES. In a particularly well-written chapter, Browner (Georgia Institute of Technology) discusses some fundamental aspects of aerosol generation and transport. Other chapters report on plasma modeling and computer simulation, spectroscopicdiagnostics, excitation mechanisms and discharge characteristics, and a somewhat philosophical chapter by Broekaert and Tolg (Institute for Spectroscopy, Dortmund, West Germany) on the status and trends of development of atomic spectrometric methods for elemental trace determinations. ?“IS TWOVOLUME BOOK I S ALSO HIGHLY RECOMMENDED. now injection analysis (FIA) is currently being used extensively as a method for sample introduction into various flames and plasmas. Valcarcel and Luque de Castro (A19) have written an excellent account on the princi les and applications of FIA in analytical chemistry. This {ook will be of great interest to emission spectroscopists. Adler (A20)has written a very interesting book on the analysis of extraterrestrial materials. The book includes descriptions of lunar, Martian, and Venusian studies accomplished (up to 1985) by the United States and the Soviet Union. Volume 10 of T h e New Metals Handbook has been published by the American Society for Metals; it is a study of materials characterization (A21). A recently published book on silicate rock analysis (A22) describes methods in which the sample is taken up into solution before determination by optical spectrometry. The chapters on ICP-AES and atomic absorption spectrophotometry (AAS) are extremely well done providing a wealth of information on the theoretical and practical application of these techniques. Welz (A23)has written the 2nd edition of his popular AAS book. Even though the book is on AAS, there is still much information useful to those using emission techniques. Several interesting books on lasers have appeared during the past two years. Andrews (A24) has written a book that provides a concise overview of lasers and their uses in chemistry. About one-third of the book is devoted to the principles of lasers and the special properties of their beams. Piepmeier (A25)has edited a most useful book entitled Analytical Applications of Lasers. Radziemski and co-workers (A.26)have edited a book entitled Laser Spectroscopy and its Applications, Zharov and Letokhov ( A 2 9 have written Laser Optoacoustic Spectroscopy, and Siegman (A.28) has written a very general book simply entitled Lasers. A book entitled Laser Scattering Spectroscopy of Biological Objects (A29) is actually the proceedings of the International Conference on Laser Scattering Spectroscopy of Biological Objects, held in Prague, Czechoslovakia, from July 6 to 10, 1986. A wellwritten book by Hollas entitled Modern Spectroscopy (A30) gives a concise account of the principles of laser action and the main types of lasers currently being used. There is also a discussion of the uses of lasers in spectroscopy. Hernandez (A31)has written an excellent book on FabryPerot interferometers. The book consists of eight chapters plus a glossary, bibliography, and indexes. The bibliography 344R * ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
contains over 400 references and describes nearly 90 years of Fabry-Perot development. Steel (A32) has also written a book entitled Interferometry. Currell’s more general book entitled Instrumentation (A33)contains information on spectroscopic theory as does Principles of Chemical Instrumentation (A34) by Bender. Stock and Orna (A35) have edited a fascinating book entitled The History and Preservation of Chemical Instrumentation. This book is actually a collection of papers presented at a History of Chemistry Symposium during the Chicago ACS meeting held in September 1985. In this collection, there are 18 papers describing a wide variety of old and modem analytical techniques. The most interesting paper to readers of this review will certainly be The History of Optical Emission Techniques for the Industrial User by W. G. Angelotti. Several books on computers, statistics, etc. are noted here. Pocklington (A361 has written a book on guidelines for the development of standard methods by collaborative studies and Cheremisinoff (A37) has written a useful book on statistics for engineers and scientists. Wernimont (A38) has written a book entitled Use of Statistics to Develop and Evaluate Analytical Methods. Woodget and Cooper have written Samples and Standards (A39),a very useful pragmatic book. Jurs (A40) has written a very well done book on computer software applications in chemistry. It contains sections on numerical and nonnumerical methods as well as a section on graphics. Vernin and Chanon (A41) have written a rather general book entitled Computer Aids to Chemistry and Ouchi (A42) has written a book entitled Personal Computers for Scientists a Byte at a Time. Two recent books on chemometrics are also noted here (A43,A44). A recently published book on detectors for liquid chromatography (A45) contains some useful information on the use of the ICP as a chromatographic detector. Rosenlund has written a book (A46) on the design and operation of a modern chemical laboratory and Maize11 (A47) has written a very pragmatic book on how to find chemical information. Related to this, Braun et al. (A48)have recently published a book on the scientometric evaluation of the literature of analytical chemistry. The 5th Edition of Grant and Hackh’s Chemical Dictionary (A49) is now available. A recently published book on Applied Geochemical Analysis (A50) contains some information on emission techniques. Several “A page” Analytical Chemistry reports are of particular importance to emission spectroscopists. In an extremely well written paper, Zander ( A N ) has provided a detailed comparison of ICPs, direct current plasmas (DCPs), and microwave-induced plasmas (MIPS). His conclusions are interesting. He states that the MIP has yet to find a consistent need in plasma AES. “It is an answer looking for a problem”. Zander feels that the DCP provides a less expensive, more operationally forgiving source for plasma AES. He notes that it is an exceptionally clever optical match to the echelle spectrometer to which it has always been mated. The authors of this review concur. He does state, however, that the ICP is the de facto source of plasma AES. He concludes his review by stating that “It (the ICP) may not be the best. But there are more of them around. And all the latest, hottest work is being done with them” (A51). Slavin (A52) has written a very useful article entitled “Flames, Furnaces, Plasmas, How do we Choose?” His interesting conclusion is that flame AAS and ICP techniques are preferable at levels where these two techniques are useful. However, Slavin states that laboratories that must do determinations at levels lower than those possible by flame AAS and ICP should be equipped to use graphite furnace technology. According to Slavin, graphite furnace AAS is now no more difficult than flame AAS and probably less difficult than using ICP techniques. Scheeline and Coleman (A53) have recently discussed electrical plasma sources that can directly vaporize solids for elemental analysis. According to Meyer (A54), the ICP as a tool for spectrochemical analysis has reached maturity faster than any of its spectroscopic predecessors. In an interesting “A page“ report, Meyer (A54) traces the 25-year history of ICPs and predicts future developments. Another “A p e” report on optical spectrometry includes a discussion of %Ps (A55). A very practical report written by Borman (A56)discusses advances in microwave dissolution. Borman (A57) has also reported on a “Workshop on the La-
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ser-AtomicFrontier” held at the National Academy of Sciences in Washington, DC, in late 1985. In a useful series of papers, Dessy gives some good advice as to how to choose a personal computer (PC) (A58,A591 and also explains some of the principles and pitfalls involved in the serial and parallel interfacing of instruments to computers (A60). Another article discusses some of the complications involved in the selection of analo to-digital converters and associated front-end signal confitioning hardware (A61). Gerson and Love (A62) describe various word processors for scientific writing. Beebe and Kowalski (A63)provide valuable information on multivariate calibration and analysis and Bezegh and Janata (AM)comment on information from noise. Veillon (A65) has written a very useful “A page” report discussing the trace element analysis of biological samples. He notes, correctly, that extremely sensitive instrumentation may be available in laboratories not equipped to control contamination adequately or to verify the accuracy of the determinations. An analytical technique that may, or may not, become extremely important in the future involves the utilization of Fourier transform (FT)techniques with atomic spectroscopy. For that reason, the review article by Faires (A66) is particularly appropriate at this time. A fairly complicated topic is presented in this article in a clear orderly way. There is a description of the recently constructed Los Alamos FT-ICP spectrometer as well as a short mention of a 1-m FT spectrometer installed in a solar telescope. On this stellar subject, Lipschutz (A67) discusses meteorites which are important because they contain the oldest solar system materials available for research. Various special issues of various journals have been published during the past two years. It is appropriate to begin this discussion with a reference to the “Gordon F. Kirkbright Memorial Issue” (A68)of Spectrochimica Acta, Part B honoring the memory of an outstanding analytical spectroscopist whose premature passing has saddened us all. This special issue contains a preface written by Guest Editor Gary M. Hieftje A69)) which outlines the career and research activities of Gordon F. Kirkbright. The issue itself contains a series of articles written by researchers closely associated with Professor Kirkbright; these are discussed in appropriate sections of this review. Spectrochimica Acta, Part B has published the Proceedings of the 1985 Winter Conference on Plasma Spectrochemistry held in Leysin, Switzerland (A70); as well as the Proceedings of the 1986 Winter Conference on Plasma S ectrochemistryheld in Kailua-Kona, HI (A71). The Guest Echor for this special issue was Ramon M. Barnes of the University of Massachusetts, the conference organizer. JAAS has published a special issue based on papers presented a t the Third Biennial National Atomic Spectroscopy Symposium (BNASS) held in Bristol, England, in July 1986 (A72). This issue contains a review article by deGalan (A73) outlining a physicist’s view on current questions in atomic spectroscopy. In addition to papers published in this BNASS issue, abstracts of other papers in the society for Analytical Chemistry (incorporating the 3rd BNAAS) Bristol meeting have recently been published (A74). JAAS has also published papers from the 1987 Winter Conference on Plasma and Laser Spectrochemistry held in Lyon, France (A75). This issue contains several outstanding papers based upon plenary lectures presented at the conference. Boumans and Vrakking (A76)review ICPs with respect to line widths and shapes, detection limits, and spectral interferences and Falk and Tilch (A77) discuss atomization efficiency and the overall performance of electrothermal atomizers in AAS, furnace atomization nonthermal excitation spectrometry (FANES), and laser-excited AFS. In a somewhat related paper, Dittrich and Fuchs (A78) describe the use of molecular nonthermal excitation spectrometry (MONES) for the determination of nonmetals using diatomic molecules with a FANES nebulizer. In a significant paper, Broekaert (A79) reports on current developments (no pun intended) with glow discharge lamps (GDLs). The electrical characteristicsof these analytically relevant sources, sample volatilization, and the predominant excitation processes are discussed. In another significant paper in this issue, Browner and Zhu (A80)discuss the differences between sample introduction strategies for ICPs when used as either photon sources for AES or ion sources for MS. The concept of a coupled interface in MS is contrasted with the uncoupled interface existing in emission
spectrometry detection. Differences in the roles that analyte mass transport and solvent mass transport may play in the two types of systems are compared. McLeod (A81) has reviewed the development and current status of FIA techniques in ICP spectrometry. Topics such as direct sample introduction, dilution, calibration, and on-line sample pretreatment are used to illustrate the versatility of the FIA-ICP technique. Marshall and Hieftje (A82) have reviewed their recent work on the measurement of true as kinetic temperatures in an ICP by laser-light scattering. &+temperature measurements were performed as a function of incident rf power and spatial position in the plasma and in the presence or absence of introduced aerosol. In this special JAAS issue, Turk’s plenary lecture (A83) on laser-enhanced ionization spectroscopy in flames and plasmas and Faires’ plenary lecture (A841 on FT-ICP provide much useful information. As noted previously, a special issue of Chemistry in Britain was published (A13)to celebrate the inauguration of JAAS. This issue contains very timely article by Ebdon, Greenfield, and Sharp (A85) entitled “The Versatile Inductively Coupled Plasma”. It is certainly recommended reading. This same issue contains an article on hydride generation techniques for AAS that will also be of interest to emission spectroscopists (A86). Several recent issues of Fresenius’ Zeitschrift fur Analytische Chemie ( A 8 3 contain selected papers from the 24th Colloquium Spectroscopicum Internationale (CSI) meeting held in Garmisch-Partenkirchen, West Germany, September 15-20,1985. In a somewhat philosophical paper, Fassel (A88) reviews the past, present, and the future of the ICP. Fijalkowski (A89) discusses the significance of dc arc plasmas as radiation sources; this subject is also addressed by Pavlovic (A90). Strasheim (A91)comments on various approaches to the multielement determination of metals using AES and, in a particularly interesting paper, Gray (A92) provides an assessment of the relationship between ICP-AES and ICP-MS. Caroli (A93)reports on hollow cathode discharges (HCD) as excitation sources and Dittrich and co-workers (A94)consider molecule formation in electrothermal atomizers and report on interferences and analytical possibilities via absorption, emission, and fluorescence processes. Ruzicka, one of the fathers of FIA, s eculates (A95) on its present use and future potential in AEE and AAS. Dawson (A96) reviews selected aspects of atomic spectrometry in biology and medicine and Fuwa (A97) discusses the analysis of various environmental materials by using spectroscopic methods. This is also discussed in an article by Michaelis (A98),while Mizuike (A99) gives a general report on preconcentration techniques and Pilsko (A100) reviews the application and role of spectrochemical analysis in geological sciences. In a “fun” article, Boumans (A101) discusses a century of spectral interferences in atomic emission spectrometry and asks “Can we master them with modern apparatus and approaches?” This article is highly recommended reading!!! Amouroux and co-workers (A102) discuss some alternative uses (other than for use in emission spectrometry) for various plasmas and de Galan and van der Plas (A103) report on the physical principles and analytical performance of a low-power ICP. An article by Welz and Schubert-Jacobs (A104) on atomization mechanisms in hydride-generation AAS will also be of interest to emission spectroscopists as will Willis’ report (A105) on aerosols in flame atomic spectroscopy. Willis has also written (A106) an article reviewing requirements and applications of instrumental analytical techniques in geochemistry. Omenetto and co-workers (A107) have reviewed some theoretical and analytical considerations for pulsed sources in laser induced fluorescence and ionization spectroscopy. In a well-written two-part review, Ebdon, Hill, and Ward report on the coupling of gas chromatography (A108) and liquid chromatography (A109) with various plasmas and flames. Christian and Ruzicka (A109) have very recently discussed some new applications of FIA in ICP-AES and Broekaert (A110) has written a state-of-the-art review discussing trends in the development of optical spectrochemical trace analysis using ICPs, DCPs, and MIPS. Broekaert and Tolg (A111)have also written a very well done review outlining recent developments in atomic spectrometry for elemental trace determinations. Broekaert also continues to write an instrument column for Spectrochimica Acta, Part B; some typical columns are cited (A112, A113). Some recent speANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
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cialized ICP reviews include applications to the analysis of radioactive materials (A114),spatial emission characteristics (A115),thermal vaporization (A116),statistical considerations (A117, A118), applications in applied geology and geochemistry (A119),applications to the analysis of biochemical samples (A120), and even a review of FT-ICP techniques (A121). Montaser and Van Hoven (A122)have an in-depth review of mixed-gas, molecular-gas, and helium ICPs and these “alternative” ICPs are discussed in great detail. This is a very well-written review. Five “gurus” of analytical atomic spectrometry, namely Greenfield, Hieftje, Omenetto, Scheeline, and Slavin, have jointly written (A123) a review tracing important developments over the 25-year period 1960 through 1985. Two emission approaches are considered in detail and are based on the high-voltage spark and the ICP. This is another one of these fun to read articles that provides a great deal of information. Another useful review is that of Sparkes and Ebdon (A124),who discuss sample introduction techniques for the DCP. Broekaert, Keliher, and McLaren (A125)have selectively reviewed options to be considered when purchasing new (or used) analytical spectroscopic instrumentation. This is a very “pragmatic” paper and should be useful to those about to spend large amounts of money on analytical instrumentation. Schrenk (A126) has reviewed the historical development of flame excitation sources for analytical spectrometry and, on the subject of the history of spectroscopy, Grasselli (A127) has reviewed the Michaelson-Morley experiment on the relative motion of the earth which demonstrated that the speed of light is unaffected by the motion of the earth. Miller’s postage stamp history of chemistry (A128)will be of interest to spectroscopists and philatelists. Progress in Analytical Atomic Spectroscopy dropped the “Atomic” in 1986 to become the more general Progress in Analytical Spectroscopy and there is increased emphasis on AAS and molecular spectrometry reviews. Nevertheless, two important papers from this journal should be noted here. Voigtman and Winefordner (A1291 have reviewed time-variant filters for analytical measurements using electronic measurements systems and Blades and co-workers (A130) have reported on excitation, ionization, and spectral line emission in the ICP. Lastly, our 1988 award for the “most fun and useful” article goes to Robert A. Chalmers, the Editor of Talanta,for his very useful article entitled “The Analysis of a Paper on Analytical Chemistry” (A131). This article should be read by a l l authors of scientific papers as well as by reviewers and editors. It should be noted that this article was published in a special issue of Talanta (A132)honoring Dr. Chalmers for his many years of service as Editor.
SPECTRAL DESCRIPTIONS AND CLASSIFICATIONS This year we have eliminated the tabular presentation of selected references (A1-A4) and adopted a completely narrative approach. Comments regarding this change in format are welcome. In a very interesting paper, Boumans and Vrakking ( B I ) present data on the widths and shapes of approximately 350 prominent lines of 65 elements emitted by an ICP. An atlas of approximately 90 line profiles, and a table detailing physical and Doppler widths, and wavelengths and relative intensities of HFS components are included. Blades et al. (B2) discuss LTE, ion-atom intensity ratios, electron number distribution measurements, analyte ionization mechanisms, and excited state level populations in a review with 160 references. Balfour and Chandrasekhar (B3) present the emission spectrum of the indium chloride ion (InCl+)between 360 and 420 nm. Sixteen bands were classified for the system. Chanq and Lee (B4) report the observation of chemiluminescence in the 290-520 nm range during warming of microwave-discharged mixtures of CSz/Nz/Ar, CO/N2/Ar, and CH4/N2/Ar. They attributed the most intense progression to the vl sequence of the a3 2,+ - XIZ,+transition of C2N2 Huber, Klug, and Alberti (B5) photographed the jet emission spectrum of the CN radical in the UV and Schumann regions from approximately 150 to 350 nm. Majewski et al. (B6)have assigned 113 emission lines of the v2 band of H3+ by using a highpressure hollow cathode discharge cell and Fourier transform 346R
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spectrometer. Montaser and co-workers (B7) have studied the signal-to-background ratios of the prominent lines of 45 elements in a low-power (1200 W) Ar-N inductively coupled plasma. They report that the use of pure nitrogen in the outer flow of the plasma improves the detection limits of a number of elements. Greenfield, Malcolm, and Thomsen (B8) have recorded the resonance and nonresonance fluorescence spectrum of Pb by using ICP-AFS. Sensitivityat the ppb level was attained at several nonresonance wavelengths, and remarkable freedom from spectral interferences was observed. The radial intensity distributions of atom and ion lines of Be, Mg, Zn, and Li were measured by Kovacic and Barnes (B9) and compared to theoretical distributions. The model used simulated the observed distributions satisfactorily for radii between 1and 3 mm. Gillson and Horlick (B10)mapped the fluorescence from neutral calcium atoms and ions in the inductively coupled plasma. These maps were compared with emission maps of the same species. Data are also presented for Sr and Mo. Furuta (B11)used the vertical and radial emission profiles of various yttrium species to demonstrate that excitation is predominately due to electron collisions in the NAZ (normal analytical zone). He also confirms that the ICP is close to local thermal equilibrium in the NAZ. Choot and Horlick (B12) used a photodiode array spectromter to produce radially resolved electron density maps of Ar, Ar/Nz, and Ar/02 inductively coupled plasmas. They report maximum values of approximately 7 x ioi5 electrons/cm3 at 3.5 mm off axis and 5 mm above the load coil, and (3-4) X 1015 in the aerosol channel 10 mm above the load coil. Burton and Blades (B13)compared the emission profiles of Fe atom and ion lines in conventional and low power, low flow ICP torches. Excitation temperature profile differences were attributed to the differences in gas flow dynamics between the two torches. Choot and Horlick (B14) followed the changes the vertical spatial emission structure for a variety of analytes in an ICP when the Ar coolant is gradually replaced by Nz. They found that, in general, as the fraction of Nz in the coolant is increased, the zone of maximum emission shifts downward toward the load coil, and the intensity of ion line emission increases relative to that of neutral atom line emission. The accurate determination of temperatures in plasma emission sources is still an area of great interest. Fishman, Il’in, and Salakhov (B15) give an analysis of temperature determination methods based on self-reversedlines in optically thick plasmas. Hasegawa and Winefordner (B16) determined a temperature of approximately 4000 K at an observation height of 70 mm above the load coil from the emission spectra of the N2 second position bands. They suggest that energy gained from collisions with electrons is lost through radial heat conduction. Seliskar, Miller, and Fleitz (B17)also used the N2rotational bands to determine plasma temperatures. Hart, Smith, and Omenetto (B18)demonstrated that the absolute number densities of the metastable and radiative 4s Ar levels approach the values predicted by the Boltzmann equilibrium for a temperature of 6500 K. Gerasimov et al. (B19)examined the dependence of the concentration of Ar atoms in the 1s3 metastable and 1s4resonance states on the distance from the load coil. Marshall and Hieftje (B20) employed laser light Rayleigh scattering to measure localized gas densities and derive gas kinetic temperatures in an ICP. The reported temperatures were slightly higher than those obtained by Doppler broadening methods. Brown et al. (B21) used the 306.4-nm OH band to calculate a temperature of 3580 K for the central region of a moderate power (500 W) Ar microwave induced plasma (MIP). A discussion of rotational state distributions as they are related to LTE and temperature determinations is included. Huang and Liu (22) discuss the decay of an ICP above the load coil. They comment on the role of compression heating in sustaining the plasma, and the importance of radial convection in temperature profiles. Tang and Trassy (B23) studied the influence of water on the analyte excitation temperatures in an ICP. They show that it is H, provided by the dissociation of water, that has a predominant role in the thermal exchange process between the sample and the plasma. Fanin, Miller, and Seliskar (B24) provide experimental evidence for a simple kinetic model describing the population of the q3Pand qlP states of helium in a 27-MHz He-ICP. Van der Mullen et al. (B25) use Boltzmann-Saha plots to show that magnesium is close to LTE throughout an inductively
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coupled plasma. They developed a simple model which shows that charge transfer is the dominant excitation mechanism in an ICP, and deviations from LTE are only observed in levels sensitive to charge exchange with argon ions. Parisi and Heiftje (B26)have studied the effects of a sinusoidally modulated power source on excitation in an ICP-AFS system. They found that the plasma exhibits a nonlinear response to changes in input power, and that the maximum excitation temperature is correlated with the peak of the modulation waveform, while the fluorescence intensity is related to the valley of the modulation. McCann, Chen, and Payne (B27) used a combination of a NdYAG laser and a dye laser to measure the energy levels in Ar and Kr. The amount of photoionization was calculated and agrees well with observation. Kielkopf and Myneni (B28) used a Fabry-Perot interferometer to study the H-a Balmer line emitted by a lowexcitation electric discharge at liquid nitrogen and room temperatures. The data were used to determine the amount of excitation energy transferred by neutral collisions. Bluemel and Smilansky (B29) discuss radiation induced ionization of hydrogen atoms in fields below the classical ionization threshold. They found that ionization occurs due to enhanced population of a band of high n states that ionize easily. Black and Jusinski (B30) utilized resonance enhanced multiphoton ionization (REMPI) to detect atomic nitrogen(%) as a result of the two-photon dissociation of N20 in microwave discharges of mixtures of N2 and Ar. An increase in the N2 fraction of the mixture resulted in a decrease in the N(2D) signal. Hasegawa and Winefordner (B31) demonstrated that argon collisions are the dominant excitation mechanism for rotational transitions of N2, while vibrational transitions are not easily characterized. Sekiya, Tsuji, and Nishimura (B32) studied the He+-N2 charge transfer reaction in both a conventional flowing-afterglow apparatus and a low-pressure apparatus. The N2+-C2, N2+-B2,and N2+-D1emission s stems were observed in the 190-320 nm region, with the N2Y D’ emission predominating in the 210-260 nm region. Niefer and co-workers (B33) measured the fine structure mixing of mercury 6s6d states through collisions with Hg, Ar, and N2 Cross sections for all transfers are presented. Walker and Blades (B34,B35) used a 4096 pixel linear photodiode array spectrometer to determine the emission intensities of 22 atomic and 26 ionic iron lines and 16 atomic and 16 ionic chromium lines in an ICP. Their results indicate that excited state populations for atom lines are nonlinear with respect to excitation energy, while ion lines exhibit a linear relationship. The results are discussed in terms of a partial LTE model. Hasegawa and Haraguchi (B36)have developed a collisional-radiativeprocess theory to explain the excitation mechanisms of magnesium in an Ar ICP. By comparing reactions rates for ionization processes, they determined that electronic impact is the dominant excitation/ionization mechanism for Mg, rather than Penning ionization or charge transfer reactions. Smith, Hart, and Omenetto (B37) measured the ionization yield from both single-step and two-step laser-induced excitation, followed by collisional ionization of lithium atoms in a separated airacetylene flame. They estimated collisional ionization rate coefficientsand discussed the analytical sensitivities attainable by both excitation techniques. Vaughan and Doering (B38) measured the absolute differential and integral electron excitation cross sections for the 98.9 nm atomic oxygen 3P-3D transition. Their data are a factor of 2 lower than previous estimates and agree favorably with aurora and dayglow emission intensities. Similarly, Zipf (B39) has studied the excitation of the S3So-2p3P oxygen resonance transition at 130.4 nm. His cross-section estimates are a factor of 2-3 lower than previous estimates but are in good agreement with recent quantum calculations. Niggli and Huber (B40) used a Fourier transform spectrometer to make emission measurements of a hollow cathode discharge containing barium. The branching fractions, and from them, the transition probabilities of eight upper levels were calculated, with accuracies of 1% to 60%. Wujec and Musielok (B41)determined the transition probabilities of 211 V I1 lines from 234 to 420 nm in a wall-stabilized helium arc. The results are compared with previous experimental work as well as theoretical calculations. Walters and Niewoudt (B42) used the half width of the Stark broadened H-@ line to determine the electron number density in a 27.12-MHz,
1200-W ICP. From these measurements, the transition probabilities of three Ar lines were determined via the two-line method. Piper (B43) measured the radiative lifetime of the lowest excited singlet state of nitrogen in a discharge flow reactor. The metastable species were generated in a hollow cathode dc discharge through nitrogen in argon and detected by vacuum UV fluorescence. Measured lifetimes were in the area of 23 ms. Schade and Helbig (B44) determined the lifetimes of 10 Ta I1 levels by using pulsed laser excitation and time-resolved observation of the reemitted fluorescence. Zhechev and Koleva (B45)used Hanle signals to determine the lifetimes of P I1 levels and compare them to previous values obtained with beam-foil spectroscopy. High-frequency discharge excitation in a hollow cathode dicharge was used to provide the necessary degree of coherence. A novel laser spectroscopic technique providing excellent signal to noise performance and high spectral resolution is described by Tong and Chen (B46). The potential of the technique is demonstrated by resolving the sodium D~ HFS lines. Czerwinska (B47) determined the extent of electricquadrupole radiation admixture in three bismuth atom lines and one bismuth ion line via a computer program using experimentally determined hyperfine structure and Zeeman pattern data for various magnetic fields as input. Rose et al. (B48) describe the use of picosecond grating experiments as a new type of high-resolution time domain spectroscopy. As an example of the technique, the ground and excited-state hyperfine frequencies of sodium were determined. Femenias and co-workers (B49) used grating and Fourier transform spectroscopy to study the rotational structure of the optical spectrum of niobium oxide. Preliminary rotational constants for the X42- state are presented. Zhu, Xu, and Gallagher (B50) used multistep laser excitation and time-of-flight to determine energy and angular distributions of electrons ejected from the strontium 5pns J = 1 autoionizing series. A sixchannel quantum defect theory was developed from the data. Jones, Pichler, and Wiese (B51) studied the line profiles of plasma broadened and slightly red- or blue-shifted spectral lines of argon and nitrogen in a wall stabilized arc. The results for red-shifted lines are in close agreement with the quasistatic theory of line broadening, but the blue-shifted lines exhibit a reversal of the predicted pattern. Rea, Chang, and Hanson (B52) investigated the collisional line width of OH generated behind reflected shockwaves in hydrogen-oxygenargon and hydrogen-oxygen-nitrogen mixtures with a rapid-tuning frequency-doubled dye laser. Lines near the 307 nm rotational transition series were examined to evaluate a possible J” dependence in the observed broadening. Nieuwesteeg, Hollander, and Alkemade (B53) examined the far wings of the sodium D lines, perturbed by neon and xenon atoms, at 990 K by fluorescence excitation. The most reliable XZ, All, and B’Z: potentials in these collisional systems are discussed. Moussounda and Ranson (B54,B55) have studied the pressure broadening of argon lines in a high-pressure plasma sustained by surface microwave propagation (Surfatron). Line broadening was measured at different gas temperatures and comparisons were made to prior theoretical work. Jones, Wiese, and Woltz (B56) were able to separate the symmetrical Stark broadening and asymmetrical plasma ion broadening components of argon line profiles obtained with a wall-stabilized arc. The plasma ion broadening contribution was shown to agree well with the quasi-static theory of line broadening. Harima, Tachibana, and Urano (B57)have measured the collisionally broadened line profiles of the strontium resonance line at 421.6 nm and discuss the results in terms of the semiclassical impact and quasi-static theories. Zokai et al. (B58)examined the line profiles of the resonance lines of barium (455.4 and 493.4 nm) obtained from a flow lamp and discuss the broadening due to helium and argon. The results are discussed in the context of other group I1 metal ions. Uzelac and Konjevic (B59)measured the profile of the helium 1447.1-nm line and its forbidden component at 447.0 nm in a dense, cool plasma (electron temperature of 1.5 eV). The low-temperature data agree more closely with theoretical calculations than previous data obtained at higher temperatures. Vitel (B60) has measured the profile of the H-a line in dense plasmas produced in linear flashtubes. The full line widths at half maximum are given. Sanchez, Fulton, and Griem (B61)studied the importance of ion dynamic effects on the profiles of the Balmer a transitions of H and D. They ANALYTICAL CHEMISTRY, VOL.
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were able to closely model the experimentallyobtained profiles by employing a model using Lorentzian profiles based on relaxation theory calculations for the Stark broadening contributions. Danzmann, Gruetzmacher, and Wende (B62) describe the use of Doppler-free two-photon polarization spectroscopy to measure the Stark profiles of the hydrogen L-a line in a dense plasma. Their technique makes possible measurements under high temperature and density conditions where other subDoppler laser techniques have failed. Pittman and Konjevic (B63)measured the Stark profiles of six spectral lines belonging to 3d-4f transitions of N+ in a low-pressure pulsed arc. Electron densities and temperatures were also calculated. Walters, Gunter, and Zeeman (B64) desi ned a computerized two-motor scanning system to measure t e profile of the H-/3 line. The spatially integrated Stark profile was then converted to a radially corrected profile by using Abel inte al equations. Lemaire, Chotin, and Rostas (B65)measured t f e broadening and shift parameters of the sodium D lines perturbed by helium in a combustion-driven shock tube. The line profiles were recorded with an intensified Reticon photodiode array coupled to a high-resolution spectrograph. In two related papers, Wada, Adachi, and Hirose (B66)and Fujimaki, Adachi, and Hirose (B67) used optogalvanic spectroscopy to study line shapes of the 5p’ to 7d’ or 9d’ transitions of krypton, and Stark shifting of the Kr 8d[3/2]z-5p[!/2]z atomic line. Term values of the autoionized 7d‘ and 9d levels were determined. The theoretical aspects of line broadening have been addressed by many workers. Spielfiedel, Feautrier, and Roueff (B68)studied the 0 557.7-nm line profile perturbed by argon by using a semiclassical close coupling formalism. Radiative and collisional couplin s were included and their effects discussed. Julienne a n f Mies (B69)used the close-couplin theory to calculate the absorption profile of the Sr 1P-1 resonance line. All calculated parameters are in good agreement with experiment. Zhi and Qian (E70) describe a simple theoretical model of the spectral line profile in a turbulent gas. They decompose a Voigt profile into Lorentzian and Gaussian components, and include terms relating to turbulent motion in the Gaussian contribution. Nee (B71)used a relaxation line-broadening theory to investigate the behavior of first-order plasma satellites of Hz. The theory was generalized to higher order to describe the second harmonic satellites. Woltz (B72) has published a table of theoretical profiles of isolated spectral lines broadened by quasi-static ions. The calculations are based upon the earlier work of Griem (1974) and cover a wider frequency range and include a larger number of ion-broadening parameters than the previous work. Okada, Yoshihara, and Kitade (B73)used the Fabry-Perot interferometer and the theory of Hilbert and Schmidt to reconstruct spectral lines of various profiles. The method gives satisfactory results in the presence of Gaussian noise. Hubeny and Oxenius (B74) have made more explicit a previously published semiclassicalformulation of the atomic line profile coefficients in terms of generalized redistribution functions by deriving atomic redistribution functions for three-photon processes. The physical assumptions underlying the theory are discussed. Cope and Lovett (B75) have derived a general expression for the Voigt profile, containing general width and shift functions depending on the mass and relative speed of the perturbing body. Shannon, Harris, McHugh, and Lewis (B76) use the Ca 422.7-nm resonance line to demonstrate some inadequacies in the conventional Voigt profile expression. They provide an expression which more closely approximates experimental line profiles. Al-Sagabi and Peach (B77)derived general expressions for line profiles based upon the assumptions that all emitter-perturber interactions are additive and the perturber travels in a straight line. Good agreement with experimentally obtained line shapes of sodium perturbed by heavy rare gases was obtained. Cagigal and Gonzalez (B78, B79) used photon statistics and a multichannel analyzer system to analyze the shapes of two spectral lines with Gaussian profile and compared the results with those obtained when lines with a Lorentzian profile are similarly analyzed. Finally, Gigosos, Cardenoso, and Torres ( B O )used a computer model to compare the binary and complete binary collision approximations used in electronic Stark broadening calculations. Line profiles of the Lyman H line were generated by using both approximations and the results were compared to
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those obtained from the exact calculation.
INSTRUMENTATION This section of the review discusses those papers where the primary emphasis is on instrumental development and design. It is recognized however that the citation of a particular paper in a section of the review can be somewhat arbitrary. Sample Introduction. 1. Special Liquid Sample Introduction. Umemoto and Kubota (CI-C3)have reported many interesting applications of the direct graphite cup insertion technique in the determination of lead, tin, and bissulfur and phosphorus in solution (C2), muth in solution (CI), and arsenic and antimony in iron and steel (C3)by ICP-AES. In order to correct background changes caused by rapid insertion of the graphite cup and elimination spectral interferences due to matrices, a high-resolution echelle spectrometer was used with wavelength modulation. Borsier and Labarraque (C4) have described an electronic device for automatic regulation of sheathing gas flow rate and nebulization in an ICP to get a stability gain for routine analysis in geochemical prospecting. Horlick and co-workers (C5, C6)have presented a new design for a direct insertion system which is a mechanical system that allows precise movement of the sample cup into the ICP discharge and can be attached to commercial ICPs. Good quantitative results can be obtained for volatile elements with reasonable precision and low detection limits with the use of 10 MLof solution or 10 mg of powder. Solution nebulization into low-power MIP for atomic emission spectrometry has been of interest to many workers. Ng and Shen (C7) have used a MAK nebulizer to introduce liquid aerosols containing Cr, Mn, In, V, Pb, Sr, or Zr into a low-power (105-115 W), low argon flow (537 mL/min) MIP. Favorable detection limits in 3% nitric acid water samples were obtained compared to those reported for a 150-W ArMIP and the conventional ICP for most of the elements. Long and Perkins (CS) reported that the direct introduction of aqueous samples into a low-power MIP could be achieved with the use of a highly efficient TWlomicrowave cavity. Samples from a concentric glass nebulizer Scott type spray chamber are fed directly into the cavity wit no desolvation apparatus. This plasma is characterized as an atom cell by the study of emission profiles, working curves, and limits of detection. Ionization and vaporization interferences that occur with the use of this plasma are also discussed. A modulated sample-introduction device has been constructed and evaluated by Steele and Hieftje for use in flame emission spectrometry (C9)and ICP emission spectrometry ((210). With this device, the flow rate of aerosol to the excitation source is modulated by the application, at a specific frequency, of a pressure pulse to the nebulizer chamber; the use of frequency-selective detection permits efficient signal recovery. The construction and operation of the device are described and its performance for several elements is evaluated in terms of detection limits., S,/ B enhancement, and working-curve linearity. 2. Solid Sample Introduction. In two well-written paDers. De Silva and Guevremont ( C l l . C12) have continued theu studies on a fluidized-bed sampling system for the direct introduction of solids into an ICP. Performance parameters including several hardware design parameters and experimental parameters were optimized and internal reference methods have been applied. Ono, Saeki, and Chiba (CI3)have developed an ultrafine particle generation (UFP) system for the direct analysis of solid metal samples by ICP-AES. Fine particles are generated by a spark discharge and then swept into the ICP. Scheeline and Coleman (C14) have used electrical plasma sources for direct solid elemental analysis. They concluded that representative and effective sampling is more difficult than reproducible excitation. Brenner, Lorber, and Goldbart ( C I S ) have discussed several interference effects when a graphite cup conntaining a silicate sample is inserted horizontally into a low-power ICP. The presence of a graphite diluent can prevent glass formation, and, as a result, early volatilization, maximum signal-to-background ratios, and reduced tailing occur. An interesting solid sampling technique has been described by Luo, Jian, Zhu, and Xu (C16)in which the powder sample is bombarded by the focused giant pulsed laser beam in sequence from point to point at a repetition rate of 10-20 points per second. The aerosol produced by laser
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vaporization is introduced into the conventional ICP torch with a stream of Ar. Introduction of powder suspension and slurry is an important technique for solid sample introduction. In two reCIS) have inveslated papers, Huang and co-workers (1217, ti ated powder suspension sample introduction technique for ItP-AES. A GMK nebulizing system was modified and used to introduce powder suspension samples into the ICP. In the paper (C17),the sample introduction system and factors affecting spectral intensities were discussed and the second paper (CIS) considers some applications of this technique. In three extremely important papers, Ebdon and co-workers (CI9-C21) have systematically discussed direct atomic spectrometric analysis by slurry atomization. The parameters that affect the slurry atomization of whole coal in an ICP for AES have been investigated and analysis of whole coal was conducted by this technique with a precision of 12% (which is much better than that for flame AAS). In a related paper, Sparkes and Ebdon (C22) reported an application of slurry atomization to agricultural samples. They concluded that the slurry atomization allows solid samples to be introduced into the plasma with minimal modification to the application and allows calibration to be achieved with simple aqueous standards. Watson (C23) described a procedure for the analysis of a range of pyrometallurgicalproducts that involves the direct introduction of an aerosol of the finely divided sample suspended in a mixed liquid medium into an ICP source in an AES by a v-type Babington nebulizer. Halicz and Brenner (C24) introduced slurries of silicate rocks and their glasses and suspensions of clay minerals into an ICP with high-solid nebulizers. Monasterios, Jones, and Salin (C25) determined copper and zinc in human head hair by ICP-AES with a direct sample insertion device without digestion. The analysis of high-solids matrices using the Meinhard concentric nebulizer in ICP-AES has been commented on by Cobbold (C26) and a simple modification to the plasma torch was described to allow many high solid solutions to be aspirated continuously without blockage. 3. Gas Sample Introduction and Hydride Generation. A fast gas sampling system for ICP spectrometry has been described by Miller and Seliskar (C27). The system is based on a fast-switching valve which is coupled to a He-driven actuator and was tested by determining relative standard deviations for N2, N, H, and D.Mauty, Parsons, and Moore (C28) have modified an ICP spectrometer for gaseous sample introduction. The system uses a gas proportioner utilizing rotameters to achieve sample gas concentrations and mixing with the sample argon gas. Identification of plasma gas and plasma induced by products, both atomic and molecular, were determined. In a well-written paper by Wang and Barnes (C29), a mathematical model for continuous hydride generation with ICP spectrometry has been proposed. Hydride transfer between generation and the ICP has been modeled and experimental results for As, Pb, Sn, and Te hydrides are compared with model calculations, and deviations between them are evaluated statistically. In another related paper, the same authors (C30) studied the solution pH dependencies of hydride-forming elements, As, Pb, Se, and Sn. All of the main chemical reactions related to the hydride-forming system are considered, and detailed mathematical calculations are experimentally verified with ICP-AES. Ohls (C31)has recently described the determination of hydride-forming elements in complex matrices, such as steels, by AAS using the hydride generation system MHH-S. The possible use of the system in combination with ICP-AES is also indicated. In his experience with a miniature hydride generation device used in conjunction with MIP-AES for the determination of antimony, arsenic, lead, and tin, Barnett (C32) has found that the minature hydride generation device did not match the conventional system in terms of detection power as the improved sample transport efficiency of the miniature generator could not compensate for the larger sample volumes employed in conventional hydride generators. It did provide, however, a rapid, low-cost and reproducible means of directly introducing hydrides into an MIP. Huang and his co-workers (C33)have developed a nebulizel-hydride generator system in which large droplets of the acidified sample aerosol from a pneumatic nebulizer were trapped by the impact wall of a smoking-
pipe-shaped hydride generator, collected in its bowl, and reacted with NaBH4 solution pumped into the bowl to form volatile hydrides. Hershey and Keliher (C34) have used three commercially available hydride eneration devices in conjunction with AAS and ICP-AE8 to study the possible interelement interferences from 50 elements. They found that 19 of these elements caused signal reductions of at least 10% and concluded that these interferences could be reduced (drasticallyin some cases) by an appropriate choice of hydride generation system and by manipulation of the acid strength. There have been many applications of hydride generation in determination of hydride-forming elements in conjunction with plasma spectrometry. Walton (C35) has described the analysis of four NBS reference low-alloy steel for arsenic, antimony, and bismuth by hydride generation ICP-AES. Ek and Hulden (C36) developed a continuously operating hydride-generation system for the determination of volatile hydride-forming elements such as As and Se by DCP-AES. Boampong, Brindle, and Ponzoni ((237) have modified a commercially available hydride generator to improve the operating procedure and enhance the arsenic signal in determination of As(II1) and As(V) as total As. They found that identical results could be produced from both oxidation states of arsenic; however, as As(V) is reduced more slowly than As(III), peak areas and not peak heights must be measured when the arsine is immediately stripped from the system. When the reduction is allowed to proceed for 20 s before the arsine is stripped, peak heights may be used. Anderson, Thompson, and Culbard (C38) have studied on reaction media in selective reduction of arsenic from arsenate, arsenite, monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA). The rapid determination of As(II1) alone, DMAA alone, As(II1) + As(V) and total arsenic has been achieved. 4. Flow Injection. Garcia, Garcia, and Medel (C39) outlined a flow injection ion-exchange preconcentration procedure, using a microcolumn loaded with Amberlite IRA-400, for the simple and quantitative determination of trace amounts of aluminum in the ng L-' range by AAS and /or ICP-AES. Cook, McLeod, and Worsfold (C40) described a procedure for the deposition and elution of arsenate, borate, chromate, molybdate, phosphate, selenate, and vanadate by using activated alumina as a column packing material for adsorption of oxyanions in flow injection analysis with ICPAES. In a related paper, Cox, McLeod, Miles, and Cook (C41) have used a microcolumn of activated alumina in developing a rapid and sensitive method for the determination of sulfate based on flow injection ICP-AES. Martin and Ikrig (C42)described an automated computer intelligent sample handling system for ICP analysis by use of commercial flow injection equipment. Koropchak and Winn ((243) reported the preliminary data for application of thermospray vaporization to sample nebulization for FIA-ICPAES. Granchi, Biggerstaff, Hilliard, and Grey (C44) have combined a robot and flow injection for automated sample preparation and analysis of used oils by ICP emission spectrometry. 5. Electrothermal Vaporization. Zimnik and Sneddon (C45) have pointed out that the use of electrothermal vaporization for sample introduction of microliter volumes and microgram masses to a DCP for emission spectrometric determination of metal ions gives low detection limits, good linear dynamic range, good accuracy, and acceptable precision. Potential interferences can be minimized, but transport efficiency can be low if diffusion and condensation are not carefully controlled. Matusiewicz (C46) has discussed electrothermal vaporization for sample introduction into the ICP in analytical emission spectrometry. He concluded that the electrothermal vaporization technique employing graphite or metal electrodes for sample introduction into the ICP excitation source is an attractive alternative approach to conventional ICP sample introduction methods and in most instances detection limits are superior to those obtained with nebulization-basedsystems and comparable to those obtained with graphite furnace AAS. Kawaguchi, Zhan, and Mizuike (C47) have adopted a newly designed introduction system for ICP-AES samples, with a small vaporization chamber, a Teflon tube of 1mm diameter, and a small torch for effectively introducing and atomizing sample vapor produced by the heat of a tungsten wire with a 0.22-F capacitor. Detection limits obtained for various elements were lower than those measured ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
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EM I SS I ON SPECTROMETRY by either a similar method with layer vaporization chamber or a graphite-rod atomization method. Mitchell, Greene, and Sneddon (‘248) have presented a study on the use of electrothermal vaporization for introduction of solid sample into a DCP and were able to determine mercury in solid algal cells directly by this method. Barnett and Kirkbright (C49) coupled an inexpensive Ta “boat” vaporization device directly to an MIP plasma for the determination of iodine in hydrochloric acid. Abdillahi and Snook (C50) have used a helium MIP with bromine generation and electrothermal vaporization for sample introduction in determination of bromide. They found that fluorine, chlorine, and iodine as well as other common anions and cations do not significantly interfere with the measurements, below 100 times the amount determined, and detection limits for both techniques were 1 ng. Alvarado, Cavalli, and Omenetto (C51) have utilized a commercial ICP-AES in combination with an electrothermal atomization system for sample introduction into the plasma and modified its operation so that transient signals from the analytes can be integrated. Good signal-to-backgroundratios were achieved by ensuring that the time interval of the analyte peak was accurately selected. Sugimae and Barnes (C52)have performed a rapid, direct determination of trace elements in suspended particulate matter collected on glass fiber by means of ICP-AES with electrothermal vaporization. The adoption of a commercial electrothermal vaporization system for introduction into a three-electrode DCP was also explored by Barnes and co-workers (E21). In another related paper, Barnes and co-authors (C53) assessed the development and analytical utility of an electrothermal vaporization technique employing a Perkin-Elmer HGA-500 graphite furnace for sample introduction into the ICP. They also discussed the operational characteristics, including the effect of the length of the transport tube to the ICP torch, vaporization temperature, carrier argon flow rate, observation height above the coil, and plasma power. Browner and co-workers (C54)have reported that transport efficiency measurements made with a graphite rod electrothermal vaporizer used for ICP-AES are much higher than the values of typically found with conventional pneumatic nebulizers and spray chambers. In a paper entitled “Time Gating for the Elimination of Interferences in Electrothermal Vaporization-Inductively Coupled Plasma Atomic Emission Spectrometry” Tikkanen and Niemczyk (C55) have noted that the use of an electrothermal vaporizer as a sample introduction system for an ICP-AES allows for time sequencing of appearance times of various sample constituents according to the constituent volatilities to eliminate the spectral interference noted for A1 on As determinations and easily ionized elements on Pb, Mn, and Fe determination. Kitazume (C65) has used chemical etching and filament vaporization ICP-AES in determination of phosphorus depth profiles in semiconductor silicon. Oreshkov and Petrakiev (C57) have discussed some peculiarities of space-time distribution of the atoms of the elements in the plasma of a dc arc in a regime of anode evaporation. Matousek, Orr, and Selby (C58) have investigated the interferences due to easily ionized elements in a microwave-induced plasma system with graphite furnace sample introduction. Dean and Snook (C59) reported atomic absorption measurements above a graphite rod used as an electrothermal vaporization device for sample introduction in ICP-AES. Implications of experiments were discussed with regard to possible losses of analyte to the walls of the apparatus during transport of sample aerosol to the ICP. Kumamaru, Okamoto, and Matsuo (C60) have described a versatile sample introduction system with graphite tube furnace for ICP-AES. 6. Preconcentration. Hirata, Limeyaki, and Ikeda (C61) have developed a method utilizing a miniature ion-exchange column of Muromac A-1 (Muromachi Chemicals, Tokyo) to increase the sensitivity for aluminum, chromium(III),iron(III), titanium, and vanadium measurements by ICP-AES. Kumamaru, Nitta, Matsuo, and Kimura (C62)described a flow inanifold which permits suction-flow liquid-liquid extraction of copper in a discrete aqueous sample as its macrocyclic dioxotetramine chelate into chloroform. The detection limit is 1.5 ng cm-3 copper and the relative standard deviation is 2.2% for 100 ng c d copper by this method. In a related paper, the same research group (C63) used a citrate buffer line thruugh a suction sampling cup to introduce a discrete 350R
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aqueous sample solution into ICP-AES for the determination of lead and copper. Kamata, Nakashima, and Furukawa (C64)have described a method to determine trace amounts of thorium and uranium in coal ash by ICP-AES after extraction with 8-thenoyltrifluoroacetone and back-extraction with dilute nitric acid. By this method the detection limits were 11 pg L for thorium and 29 pg/L for uranium and relative stan ard deviations ranged from 3.00% to 8.6% for thorium and 3.9% to 4.3% for uranium. Abdullah, Fuwa, and Haraguchi (C65) have presented an electrochemical preconcentration of trace metals for simultaneous multielement determination by ICP-AES utilizing a graphite-cup direct-insertion technique, where controlled potential electrolysis of trace metals in an electrolyte solution similar to seawater has been examined by the use of a newly designed Teflon cell to allow cathodic deposition. Matusiewicz, Fish, and Malinski (C66) have described the production and use of mercury film electrodes for matrix separation and preconcentration of trace metals from biological materials prior to their determination by ICP-AES. The separation and preconcentration are achieved also by controlled potential electrolysis on mercury-plate, glassy C electrodes. 7. Use of Lasers. Mitchell, Sneddon, and Radziemski (C67) have presented a sample chamber system which can be used for direct determination of metals and cations in solid or pelletized powdered samples by laser ablation/DCP spectrometry. The same authors (C68)have recently developed and evaluated this system for the direct determination of copper in pelletized powder and solid samples. Sneddon (C69) also reported some preliminary observations on the study of matrix effects in this laser/DCP spectrometer and found that the emission intensity of Cu and Mn in a solid sample determined by laser/DCP is dependent on the type of compound and concentration of matrix. Ultratrace determination of osmium by laser excitation of precipitates has been reported by Haskell and Wright (C70). They have demonstrated excellent selectivity and sensitivity, lower detection limits, and freedom from interferences of this technique. 8. Organic Solvents. Massen and co-authors (C71)have determined solvent plasma loads of nine solvents, including water, for a wide range of nebulization conditions by making use of the so-called continuous weighing method. They concluded that the solvent saturation vapor pressure governs the solvent plasma load, whereas the evaporization factor dominated the distribution of the solvent over the liquid and vapor phase at the exit of the spray chamber. In another related paper (C72),experimental control of the solvent load of ICP and effects of the chloroform plasma load on their analytical performance have been described. Meyer (C73)has described an operation of an air ICP used for the determination of metals in xylene. Comparable detection limits are obtained by direct injection of sample aerosols produced ultrasonically without desolvation. 9. Nebulizers, Chambers, and Aerosol Formation. The Hildebrand grid nebulizer (Leeman Labs) was evaluated by Caruso and co-workers (C74) for ICP use with high solids content solutions. They commented that the nebulizer provided good long- and short-term stability for introducing synthetic Ocean water and a 5% dissolved solids solution into the ICP. The nebulizer exhibited no clogging problems or memory effects and a linear dynamic range of at least 3-4 orders of magnitude was obtained. Brotherton and Caruso (C75) also evaluated this nebulizer in the introduction of organic solvents into ICP and determined limiting aspiration rates for various organic solvents for the Hildebrand nebulizer with a mini-Pyrex spray chamber, a cooled Pyrex spray chamber, and a large Pyrex spray chamber. Cobbold (C76) has commented that certain high-solid matrices can be nebulized through a Meinhard concentric nebulizer for extended periods without blockage of the nebulizer. Nixon and Smith (C77) have compared the Jarrell-Ash, Perkin-Elmer, and modified Perkin-Elmer nebulizers for ICP analysis and presented accuracy and recision data for the determination of Ca, Mg, Fe, Zn, and 8 u in serum and urine control specimens. A study of neumatic nebulization with helium has been conducted by 8d.land Carnahan (C78)in order to characterize
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it for helium plasma system. Luffer and Salin (C79) have designed a rapid throu hput nebulizer-spray chamber system for ICP-AES. Routh (880)has utilized Fraunhofer diffraction to characterize nebulizer aerosol parameters such as median size, size distribution, relative aerosol number density, and aerosol transport efficiency. Karnick, Zitelli, and van der Wal (C81)have successfully interfaced an ultrasonic micronebulizer for effective nebulization at 2-20 pL/min liquid to allow the determination of nonvolatile analytes by microbore HPLC with flame photometric detection. An improved ultrasonic nebulizer of Teflon with a quartz transducer and nylon sampling tube was used by Fu, Duo, and Wang (C82)for ICP-AES. They commented that the nebulizer is stable with a nebulization efficiency of about 40% and is feasible for trace analytes and analytes of samples of high salt concentration. Elgersma, Maessen, and Niessen (C83)have built and tested a low-consumptionthermospray nebulizer for its possible use as an interface for an ICP system and systems using liquid flow rates of the order of 100 pL/min, while Vermeiren, Taylor, and Dams (C84) have used a thermospray nebulizer as sample introduction system for ICP-AES determination of eight elements. Koropchak and Winn (C85)have studied the fundamental characteristics of thermospray aerosols and sample introduction for atomic spectrometry. MichaudPoumel and Mermet (C86)have compared several nebulizers working below 0.8 L/min of concentric, cross-flow, Vee, frit, and ultrasonic type in terms of signal-to-noise ratio, uptake rate, efficiency, and memory effects. In a two important papers, Chen and Barnes (C87, C88) have discussed the characterization of a recycling nebulization system for ICP spectrometry. A theoretical model for this system has been developed and stability and humidified argon carrier gas and matrix and memory effects have been studied. Fassel and Bear (C89)have described an improved, continuous-flow ultrasonic nebulizer equipped with a desolvation system for generating dehydrated aerosol particles prior to their injection into analytical ICP. Uchida, Kojima, Isao, and Goto ((290) have investigated discrete nebulization for the determination of manganese by ICP-AES. A novel sample introduction system for ICP atomic spectrometry based on supercritical fluids has been described by Olesik and Olesik (C91). No nebulizer or spray chamber is used and results using C02as a supercritical fluid are reported. The development of a nebulizer system as an “interface” for ICP has been described by Gustavsson (C92)in which he pointed out that the working principle of the interface is to attain nearly 100% conversion of the sample into a dried aerosol in an excess of argon. He (C93)has presented a 31-reference review on progress with aerosol spray chambers for ICP atomic emission spectrometry. In another paper, He and co-workers (C94) have compared a cyclone chamber with a Scott-type chamber in ICP-AES and with a conical chamber in ICP-AFS. They concluded that analytical improvement was observed with the cyclone chamber. In a related paper, He and co-workers (C95) have used the cyclone spray chamber to replace the conventional Scott spray chamber in the determination of rare earths by ICP-AES. Montaser and co-authors (C96) have evaluated two cyclone spray chambers of different sizes for ICP-AES and concluded that, in general, the signal-bbackground ratios, detection limits, and precisions of the analyte signal intensities obtained with the small cyclone chamber are slightly superior to those achieved with a Scott spray chamber and a recycling gravitational sedimentation chamber. Dale and Buchanan (C97)have reported a comparison of the analytical performance of five cloud chambers of different geometry used in conjunction with a commercial concentric glass nebulizer. &in (C98)constructed a vertical cylinder-type spray chamber for ICP-AES in which the aerosol was conveyed to the plasma through concentric quartz tubes, while Guo (C99)has designed a new type of nebulizer for ICP-AES which was made of quartz and consisted of water-cooling and heating vaporization regions. Direct aerosol introduction into ICP has been achieved by Kawaguchi, Kamakura, Maeda, and Mizuike (ClOO)and relations between the decreasing rate of particle number density and particle size have been discussed. Schwartz and Meyer (C101) have investigated the characterization of aerosols generated by thermospray nebulization for atomic spectrometry. Magyar, Lienemann, and Vonmont (C102) have been
able to master the analytical problem of high background plasma emission in determination of metals in organic solutions by ICP-AAS and ICP-AES by feeding oxygen via the carrier gas flow for combustion of the emitting molecules. This droplet generator provides more stable droplet production, production of droplets over a wider range of size, and easier operation than earlier designs. Novel Spectrometer Systems. Fassel and co-workers (C103)have successfully observed optical spectra through a sampling orifice inserted directly into an ICP. The optical system does not use lenses, mirrors, or windows so that vacuum ultraviolet wavelengths as low as the ionization energy of Ar can be detected. Spatially resolved emission studies of argon resonance lines from an ICP have been reported. In a related paper (C104), the same authors have discussed the analytical figures of merit for the nonmetals, metalloids, and selected metals by ICP-AES. Qiu and co-workers (C105)have used a plane grating spectrograph in observing line hyperfine structure. Karanssios and Horlick (C106) have recently developed a new commercial spectrometer that combines a linear photodiode array detector and an echelle spectrometer with a very unique dispenion/selection/recombination line selector. In their continued work, Ma, Chen, and Tan (C107) have used the ICAP9000 multichannel spectrometer in high-purity rare-earth oxide analysis. Davis and Winefordner (C108) have evaluated a Voigt effect coherent forward scattering atomic spectrometer which involves the rotation of polarized light by atoms located within a transverse or a longitudinal magnetic field, the Voigt and the Faraday effect, respectively. By an end-on viewed ICP-AES, Pan, You, He, Wang, Ma, Huang, and Xu (C109)have determined 40 trace impurity elements in uranium compounds. Wachter and Cremers (C110) have reported the determination of uranium in solution using laser-induced breakdown spectroscopy. Millard, Dalling, and Radziemski ( C I I I) have combined a time-resolved laser-induced breakdown spectrometry with the long spark technique for the rapid determination of beryllium in beryllium-copper alloys. Omenetto and co-workers (C112)have used two excimer lasers to pump two dye lasers in the optical detection of laser-induced ionization in an ICP for the study of ion-electron recombination and ionization equilibrium. Kitagawa and Usami ((2113) have constructed a photodetector-synchronized rapid scanning spectrometer with a rotating grating directly driven by a synchronous motor. The basic analytical performance has been evaluated and some applications have been demonstrated. Hendrick and Michel (C114) have used simplex optimization and Box-Behnken partial factorial experimental design techniques to optimize the quantitative performance of a DCP system. An attempt has been made by Crawford, Rees, and Diego (C115) to measure the instrumental response function of the Mount Stromlo coude echelle spectrograph. Houk and Lim (C116) have investigated atomic emission spectrometry with a reduced-pressure afterglow extracted from an ICP. A lowpressure interface has been developed by Whitten, Kouting, Nolan, and Ramsey (C117)which permits high-resolution laser spectroscopy to be performed with an air-acetylene burner. Antoniades and Peyser ((2118) have developed an optical multichannel analyzer-based high-resolution, multipoint spectroscopic apparatus which allows a high wavelength resolution smaller than 0.02 A. Zhao and Ji (CI19)have installed an abbe comparator for adjusting the exit slit in an atomic emission spectrometer with ICP source. Levy, Quaglia, Lazure, and McGeorge (C120) have described a new spectrometer system which is based on a linear self-scanning photodiode array detector for ICP-AES. Wuensch, Dewies, Ohls, and Koch (C121) have successfully used a separate spectrometer in dual-optic simultaneous spectrometry for the measurement of all background-near analyte lines. Trukhacheva (C122) has developed a method for the suppression of the effects of apparatus distortions introduced by the optical system on the function measured in the spectroscopic diagnostics of plasma. Detectors and Torches. Photodiode array detectors and photomultiplier tubes (PMT) are still commonly used detectors. van der Plas, Uitbeijerse, de Loos-Vollebregt, and de Galan (C123) have demonstrated the use of a photodiode array as a multichannel detector for off-line continuum correction in ICP-AES. Burton and Blades (C124) have invesANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988
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tigated the influence of instrumental broadening on line shapes detected by photomultiplier tubes and photodiode array detectors. In an interesting paper, Keane and Fry (C125) have described the expansion of the domain of a red-infrared photodiode array ICP-AES to include simultaneous detection of fluorine, chlorine, bromine, and sulfur. In a short note, Carney and Goldberg (CI26) have designed an inexpensive circuit for pulsing-off a side window photomultiplier tube. In a paper on spectrochemical measurements with a multichannel integrating detector, Denton and co-workers (C127) have discussed topics related to the optimum use of integrating detectors in analytical spectroscopy. In another paper, the same authors (C128)have described a charge transfer device detector for analytical optical spectroscopy. Howard and Maynard (C129) have described a technique for the correction of gain variation in microchannel plate intensified multichannel detectors in emission spectroscopy. Sims and Denton (C130)have evaluated a solid-state camera system designed for use as a multichannel detection system for spectroscopic application. The camera is based on a charge-injection-device sensor that permits very high dynamic range operation by virtue of its unique nondestructive readout capability. van der Plas and de Galan (C131)have discussed the feasibility of a variety of potentially suitable ceramics for the segmented ICP torch. They found that the best overall results have been obtained with boron nitride and silicon nitride coated with a 10-pm layer of silicon carbide, but the lifetime of the torch is only 90 h a t 900 W rf power. Carpenter and Ebdon (C132) have optimized the analytical performance of two sample introduction-torch configurations for ICP-AES using the variable step-size simplex method and signal to background ratio as criterion of merit. Michaud-Pousse and Mermet (C133) have investigated the influence of the generator frequency and the plasma gas inlet area on torch design in ICP-AES. Their experiments were carried out up to 100 MHz, besides the conventional 27-MHz frequency, in order to design low-power, low flow rate torches. Medding, Anderson, Kaiser, and Ng (C134)have discussed the design and use of a high-precision, low-operating-cost nebulizer/torch system for ICP analysis. In an important note, Greenfield and Thomsen (C135)have demonstrated that two ICPs can be formed from one freerunning high-frequency generator. This may make ASIA (Atomizer, Source, ICP in AFS) more of a competitor to ICP-AES than it is at the moment. They also noted that two plasmas can be used in emission to separate the volatilization and excitation processes with two plasmas side by side or in line. Use of Computers. Computer-controlled instrumentation is increasingly popular. In a paper on computer-controlled optimization of an ICP, Norman and Ebdon (C136) have compared the optimized running conditions of two spray chamber designs with the same nebulizer and torch assemblies. Gu (C137) has presented a review with 23 references of computer-programmable scanning monochromators for the ICPAES technique. An inexpensive microcomputer control of instrumentation using the Commodore-64has been presented by Goliber and Michel (C138). Ottaway and co-workers (C139) have constructed an electrothermal atomic emission spectrometer system with a low-resolution monochromator which incorporates microcomputer-controlled wavelength modulation. In a related paper, Ottaway and co-workers (C140)have successfully employed an Apple IIe microcomputer to correct the background radiation in electrothermal atomization atomic emission spectrometry. Writing interface programs is a major step in interfacing instruments with microcomputer. Sara (C141) has described the principles of writing interface programs for analytical instruments and microcomputers. In a related paper, Taylor and De Donder (C142)have described the hardware adaptations and developed software which enable qualitative and semiquantitative analysis to be performed by means of a computer-controlled monochromator in combination with an ICP excitation source. Lundberg, Baxter, and Frech (C143) have combined a constant-temperature atomizer with a computer-controlled echelle spectrometer system for graphite atomic emission spectrometry. Hareland, Grant, Ward, and Anderson (C144) have developed a computer-controlled densitometer for data acquisition and high-speed analysis of photographically recorded optical emission spectra. Computer 352R
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algorithms for locating and identifying peaks and for calculating the wavelengths of spectral lines from their positions in the spectrum are described. Broekaert and co-workers (C145) have presented a microcomputer-controlled dualchannel monochromator for plasma atomic emission spectrometry with time-constant and transient signals. RyanHotchkiss and Ingle (C146)have demonstrated a computerbased data-acquisition system for an intensified diode array detector. They found the unique combination of hardware and software provides many data-acquisition and calculation options useful for multiple-wavelength spectrometric measurements. By an IBM-PC interfaced with a first-generation SIT Vidicon/OMA, Hieftje and co-workers (C147) have successfully studied two-dimensional images of spectroscopic sources including the control of the instrument and the collection, manipulation, and storage of data. Karanassios and Horlick (C148) have designed a dualprocessor, distributed-intelligence approach to the computerization of an atomic emission spectrometer in which one processor handles data acquisition and instrument control and the second processor handles data presentation and user interaction. Ficher, Lee, and Mara (C149)have described some techniques for evaluating control of automated multideterminant analytical instruments by computer. Cerino (C150) has described an integrated system consisting of the PerkinElmer Masterlab system for sample preparation, the plasma I1 emission spectrometer for analysis, and the LIMS 2000 laboratory information management system for data archival. Huang and co-workers (C151) have investigated spectral interferences of the matrix elements in soil and sediment with the “polychromatorscan” software of a Baird ICP. Lewis and Megargle (C152)have developed a custom data system for an emission spectrometry workstation equipped with a combination of ICP and dc arc excitation sources and photograph and photomultiplier tube detection. Chromatographic Detection System. 1. Gas Chromatographic (GC) Detection. There is much interest in this area. In an important paper, Jin and co-workers (C153)have reported some observations on the development of a novel gas chromatographic microwave plasma torch ionization detector (MPTID). In a related paper, the same group (C154) has studied the analytical performance of the MPTID system and successfully reported detection limits for benzene of g/s and a linear dynamic range of lo3. Goode and Kimbrough (C155)have performed an experimental study of the signalto-noise ratio in the microwave-induced plasma gas chromatographic detector while Zeng, Jia, and Yu ((2156) have investigated the operating parameters and applications of GCatmospheric pressure helium MIP emission spectrometry. Riviere and Mermet (C157) have used a MIP produced by a surfatron structure as an element-selective detector for a capillary-column gas chromatography. Applications of MIP as a detector for GC have been reported by many researchers. In a significant paper, Tsunoda, Matsumotom, Haraguchi, and Fuwa (C158)have determined dimethyl selenide in biological samples by using GC and MIP-AES, while Baumann and Heumann (C159)described an analytical procedure for the determination of different organobromine compounds in vehicle exhaust gases by using a GC/microwave plasma system. Mohamadm, Zerezghi, and Caruso (C160) have presented an initial investigation of a low-power (
