Nuclear and radiochemical analysis - Analytical ... - ACS Publications

Anal. Chem. 1908. 6 0 , 42R-62R (E115) Berger, G. S. A&. X-Ray Anal. 1986, 2 9 , 581-585. (E116) EMecker, R.; Jackwerth, E. Fresenius’ 2.Anal. Chem. 1987, 328, 469-474. (E117) Lytle, N. W.; HIII, M. W.; Mangelson, N. F.; Kwak, S. S. W. Nucl. Instrum. Methods RIP. Res. lS87, 8 2 2 , 104-108. (E118) Wolf, E.; Wegschelder, W.; Kolmer, H. Adv. X-Ray Anal. 1987, 3 0 , 273-280. (E119) Nielson, K. K.; Rogers, V. C.; Mahoney, A. W. Adv. X-Ray Anal.

1986, 2 9 , 551-556. (E120) Rastegar, 6.;Jundt. F.; Gallmann, A.; Rastegar. F.; Leroy, M. J. F. X-Ray Spectrom. 1986, 15, 83-86. (€121) Helsen, J. A,; Vrebos, B. A. R. X-Ray Spectrom. 1988, 15, 173-175. (E122) NovoseCRadovic, V.; Maljkovlc, D. X-Ray Specfrom. 1987, 16, 2 11-2 15. (€123) Cross, J. B.; Jones, R. D. Adv. X-Ray Anal. 1987, 3 0 , 89-96.

Nuclear and Radiochemical Analysis William D. Ehmann* and Steven W. Yates Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055

In this, our second fundamental review under the present authorship and title, we have chosen to continue our emphasis on topics representing the use of nuclear properties for chemical analysis. Excluded are topics in the areas of health physics, nuclear spectroscopy (unless directly related to analysis), nuclear engineering, fusion, radioactive waste disposal, fallout, and nuclear and particle physics. Other topics plasma desuch as particle-induced X-ray emission (PEE), sorption mass spectrometry, radioimmunoassay, Mossbauer spectroscopy, nuclear dating methods, and radiotracer applications are treated briefly here, since they are adequately covered in other current reviews in this or other major journals. Only a brief mention is made of well logging, since many of the advances in this field do not currently appear in the open literature. As in our previous review, we finish with short comments on some interesting developments in nuclear and radiochemistry that are not strictly analytical in nature. This review is based largely on a computerized keyword search of Chemical Abstracts (CA) for the period from midNovember 1985 through December 31, 1987. Due to the normal delay in abstracting and entering the data into the computer files, this search may not include articles that appeared in late 1987 issues of some journals. These will appear in our next review. Approximately 50% of the articles reviewed were again found by searching with the keyphase “radiochemical analysis”. In general, we have excluded papers in the form of agency, laboratory, or industry reports, patents, legs accessible conference proceedings, and publications in less common languages. Exceptions are made where the material is unique and not well represented in other more accessible publications. In the latter case, and for all non-English publications, CA citations are appended to the references. We have tried to select representative publications and, especially in the lists of applications, make no claim to complete coverage. We ho e the topics and the selected publications we have includecfwill provide a t least a starting point for your personal review of advances in the area of nuclear methods of analysis.

A. BOOKS AND REVIEWS We have again chosen to review comprehensive books and review articles separately from ori inal research publications. Table I presents a list of selectec! books and reviews which we feel will be of greatest interest to our readers. Six books published since our 1986 review (AI) offer a broad coverage of radiochemistry, nuclear chemistry, or popular nuclear methods of analysis. All are published in English. The most comprehensive is in the series Treatise on Analytical Chemistry, edited by I. M. Kolthoff and P. J. Elving for Wiley (AZ). This portion of the series is identified as Volume 14, Section K, and is entitled “Nuclear Activation and Radioisotopic Methods of Analysis”. This formidable work consisting of 795 pa es was written b 18 European authors. Portions of the vofume are devotedTto a presentation of the fundamentals of nuclear and radiochemistry, radiation detectors, radiotracers, radioimmunoassay, nuclear activation analysis, and selected applications of nuclear methods of analysis. Among the applications reviewed are analyses of high-purity 42 R

materials and samples of interest to those engaged in biological, environmental, geochemical, cosmochemical,and archaeological research. This is an extremely useful book and is a “must” for every laboratory using nuclear methods of analysis. Unfortunately, its high cost will probably preclude its use as a textbook. The CRC Handbook of Fast Neutron Generators by J. Csikai (A3) is an excellent review of neutron eenerator technology and applications of fast neutron actiiation analysis (FNAA). The handbook consists of two volumes totaling 466 pages. The first volume describes the principles of operation and output characteristics of small accelerators that are used as neutron generators. The second volume presents a discussion of fundamental nuclear research with neutron generators, nuclear data measurement methods, and fast neutron cross section data. These volumes are also a valuable source of references. A Guide to Practical Radiochemistry edited by An. N. Nesmeyanov is a two-volume English translation of the Russian work (A4). Volume 1contains 312 pages covering general principles of radiochemistry, chemical and electrochemical methods in radiochemistry,and hot atom chemistry. Volume 2 with 446 pages covers the chemical methods of preparation and analysis of the “radioactive elements”-e.g., Tc, U, Th, and the transuranium elements. Examples of the use of radiotracers are included. The book is essentially a textbook consisting of a collection of laboratory experiments and demonstrations interspersed with a brief text. It is doubtful if the approach used in this book would fit into curricula normally used for radiochemistry courses in the United States. The book by W. Geary entitled “RadiochemicalMethods” is a 229 page volume in the series Analytical Chemistry by Open Learning published in England by Wiley (A5). This is a textbook prepared for self-study outside the traditional classroom. The format consists of brief text followed by self-assessment questions. Answers are provided. Topics included the principles of radiochemistry, preparation of radioactive materials, nuclear instrumentation, radioimmunoassay, nuclear activation analysis, tracer methodology, and radiation protection. The book would be particularly useful for on-the-job training of technical personnel in industrial facilities that use radioactive materials or employ nuclear methods of analysis. Nuclear Chemistry by A. VBrtes and I. Kiss (A6) is part of the series Topics in Inorganic and General Chemistry by Elsevier Science Publishers. The notice of publication arrived too late for us to obtain an examination copy, but the prospectus for the approximately 600 page volume states that it is an introduction to the application of nuclear science in modern chemistry. Chapters cover basic phenomena and concepts in nuclear physics, characterization of chemical structure based on interactions of radiation with matter, radioactive tracing, the chemistry of ultralow concentrations, hot atom chemistry, radiation chemistry, isotope effects, isotope enrichment, and nuclear reactors. The book is described as a textbook for students in chemistry, chemical engineering, geology, and biology, as well as a reference book

0003-2700/88/0360-42R~06.50/0 0 1988 American Chemical Society

NUCLEAR AND RADIOCHEMICAL ANALYSIS

Table 1. Selected Bwks and Reviews in Radiochemistry. Nuclear Chemistry. and Nuclear Methods of Analysis

wII*n D. mmam )a a pmlessm in lhe Chemism Department 01 the UniverstQ 01 Kentucky

He

received

hls B S and M S

W e e 6 in chemism hm the UniventQ 01 WkcOnSln at Madlson and his ph D in r a d b

Chemism under Me direction 01 Truman P.

-.: ,

Joined the faculty 01 the University 01 Kentucky In 1958. At me University 01 Ksntucky he had been elected DIstingulshBd FTOI~SMX of the College of Arts and ScC enws. appointed University Research Prolessor, rewived the Sturgiii Award lor contributions to graduate education. and served 8s Chairman 01 the Department of Chemistry and ASSOCiate Dean fw Research In the Qaduate School. He has also been a Fullbright Research Fellow at the lnstnute for Advanced Studies of the Australian National University and a vlsnlng schokr at Arlzona State University and Florida State University. HIS research Interests include lnnovati~eapproaches to bace element analytical chemistry using nuclear methods, especially as ap. plied lo rewarch pobbms In geochemlshy and cormochemlshy, and studies of me re$tbnships 01 brain trace element ImbalanceS 10 neurological disear es. Steven W. Vales is a pmlsssor in lhe Chemism Department of the University of Kentucky. H e received his 0,s. degree in chemism horn the Unlversny 01 Missouri at &iumbk and hls Ph.D. in nuclear chemishy horn Purdue University (1973). Alter 2 years of postdoctaai research at Argonne Natlonai LBbOTato~y.Dr. ‘fates Mned me IacutQ at lhe UnivevsrstQ of Kentucky in lhe Unbersity 01 Kentuc1975. He r&ed ky Research Foundation Award in 1981 and was a visRlng scholar at the KFAJuellch. West Germany. His research efforts have been primarily In baslc nuclear spechoscopy and nuclear structure studles 01 delamed and trensnional nuclei. but he makes an occasional excursion into applying aCCeierator-baSBd techniques for elemental analysis.

Nuclear Activation Methods methodology general and comprehensive FNAA PGNAA CPAA RNAA

and NDP

derivative methods group separations individual elements preconcentration, molecular, sample treatment eyelie N A A errors, accuracy, precision, calculations neutron sources applications environmental forensic geology, geochemistry high-purity materials industrial ceramics microelectronics on-line analysis medicine, hiomedicsl general in vivo nutrition tissues, hair, body fluids Isotope Dilution Analysis radioreceptor assay, radioimmunoassay other Tomography, Radiography

A1-2, A4-I, A 1 6 2 2 AS, A23-24 A 25, A51, A115 .. . . . .A26-30, AU7

...

A31 A32 A33 A34 A35 A36-38, A85 A39-40 A41-45 A46 A4Q, A41. A50-51 A48 A124 A49, A83-84 A5C-51 A52-55, A81 A35, A56-51 A58 A59-62, A88 A6361 A68 A12, A69, A122

Ian-Beam Methods PIGE

A28, A M , AIO, A89 A21, A28, A54, A81, A101-103, A110, A124 A25, A28 A49, AIO, A81, A91-93, A108, A113 A28, A81, A105-113, A123 A l l , A l l , A90, A94-104, A106 A109

PIXE

for industrial personnel who deal with practical aspects of nuclear energy. Again, the high price of this book will probably limit ita use as a textbook in university radiochemistry or nuclear chemistry courses. The last of the more comprehensive new books is Essenrials of Nuclear Chemistry. 2nd Ed. hy H. J. Arnikar ( A n . This 343 page volume published by Wiley Eastern Ltd.in 1987 is the second edition of a textbook first puhlished in 1982. Chapters include The Atomir Nucleus, Properties of Nurleons and Nuclei, Radioactivity, Nuclear Reartions, Nuclear Fission, tiurlear Reactors, Applications of hdioartivity. and Elements of Radiation Chemistry. Additiuns in this edition include more material on nurlear magnetism and NMH, and disrus&omof the chemical evolution of the elemenm. thermonuclear fusion, Indian nuclear reactors, and the Oklo fossil nurlear reactnr. The txmk is largely nonmathematical hut does inrlude some numerical problems with answers. The volume shnuld meet the needs of an introdumry course in nurlear chemistry at the senior undergraduate level. Other new books address more specialized topirs. Radioharmaceuticals: Progress and Cliniral Perspectiues edited y A . R. Fritzberg ior CRC Press (A@,examines radiopharmaceuticals from both the clinical and researrh perspectives. In the same area, Ana1,tical and Chromatographic Techniques in Radii,pharmnreutiral Chemisrry edited by D. M. Wieland, M. C. Tobes. and T. J . Manger fur Springer-Verlag ( A ~ covers J many useful radiorhromatographic techniques. Data for Rndioactit.r M’asrr Management and Nuclear Applications authored by D. C. Stewan for John Wiley and Snns (A101 discusses radioactive waste management and includes some information useful in neutron activation methods. The F’roron Microprobe: Applirafionq in rhe Biomediral Field authored by R. D. Vis and puhlished by CRC Press ( A l l ) considers the analytical capabilities of the nurkar mirroprobe. Positron fi’mission Tomojiraphj is the title of a new book Inr. S,(A12). edited hy M. Heivirh and A. Alavi for Alan R. I:LS Finally. the twcwolume second edition of The Chemisrry of

E

RBS nuclear reaction analysis nuclear microprobes Transmission. Attenuation, Scattering

A21, A51, A54, A51, A I 2 , A86, A l l 0

Stds for Nuclear Elemental Analysis

Methods

A36-31, A13

Well Logging A15

Instrumentation y spectroscopy neutron detectors Tracer Studies biological, medical pharmaceutical environmental industrial Isotopic Dating Methods accelerator-based,general accelerator-based.target preparation conventional methods Related Topics actinide chemistry radioactive waste management

A14 A114 A&9. A44, A55, Al5-79 A44, A80 A81-82 A116120 A121 A125-129 A13 A10

the Actinide Elements edited by J. J. Katz. G. T. Seaborg, and L. R. Morss (A13) has been released by Chapman and Hall Publishers. ANALYTICAL CHEMISTRY, VOL.

BO, NO. 12. JUNE 15. 1988 43R


In old businew, we erroneously stated in our previous review that the book Emanation Thermal Analysis and Other Radiometric Emanation Techniques by V. Balek and J. Toelgyessy (A14) was in Hungarian, as reported by Chemical Abstracts. We received letters noting that the book, jointly published in 1984 by Akadgmiai Kiad6 (Hungary)and Elsevier Scientific Publishing Co., was in English. We also failed to note the publication of the 1984 book by A. W. Wylie entitled Nuclear Assaying of Mining Boreholes which was published by Elsevier (A15).

B. NUCLEAR ACTIVATION METHODS 1. Instrumental Thermal Neutron Activation Analysis (INAA). Publications demonstrating the applications of INAA continue to be numerous. It is still the method of choice for precise, accurate, multielemental analyses of complex matrices. However, the technique is clearly mature and relatively few major advances in methodology have been reported during the last several years. In our 1986 fundamental review, we noted the great potential for the use of activable (some prefer the term 'activatable") tracers with detection by INAA. Unfortunately, few further developments have been reported. Whitley and Aggett (B1)spiked infant diet with 58Feand 63Custable isotopic tracers to study mineral uptake for term and preterm babies. 58Fewas determined by INAA and @Cuand 65Cuby RNAA. Nakaishi et al. (B2) used Eu and Au as activable tracers in the INAA investigation of debris from glass target materials in laser fusion research. Derivative activation analysis (DAA) is a method that is also based on an activable tracer. In this method, the element or chemical entity to be determined is either replaced or complexed with a surrogate element for which NAA has an enhanced sensitivity. Principles of the method and several applications (e.g., determination of P, Ni, T1) have been published by Ehmann et al. (A31). Isakander (B3) brominated a variety of edible oils and used DAA to successfully measure unsaturation of the oils. Frasch et al. (B4) used Ag binding followed by INAA determination of % to measure protein concentrations. They found that the binding of Ag is not specific to any charged or polar groups on the proteins, and the molar Ag to protein ratios exhibited relatively small differences for the variety of proteins report that results they examined. Kleppinger and Yates (E) of student laboratory experiments for the determination of P by DAA and directly by FNAA compare favorably. The use of very short or pulsed reactor irradiations is an area of greatly increased interest during the current review period. Short-time activation analysis employing detection of indicator radionuclides with half-lives in the subsecond to 20-s range has been used by Grass et al. (B6)to analyze geological samples and NBS SRM 1648, urban air particulates. The principles of a "loss-free counting system" and detection sensitivities for geochemical applications are also presented. Bode et al. (B7)describe a microprocessor-controlledfacility at the Interuniversity Reactor Institute, Delft, Netherlands, for use with short half-life radionuclides. A fast "rabbit" sample transfer s stem constructed of plastic and carbon fiber to minimize rabcit contamination activities and computer control procedures are described. Trends in instrumentation for the use of short-lived radionuclides in INAA are reviewed by Westphal et al. (B8).They also describe a state-of-the-art y-ray spectroscopy system for very high counting rates and a new method for high-resolution and high through-put processing of nuclear detector signals. Truglio and Guinn (B9) have developed an INAA Advance Prediction Computer Program that has been applied to a variety of biological and environmental reference standards to determine INAA detection limits based on short-lived product radionuclides and total analysis times of 1.5-192 s. The determination of B via 20-ms half-live 12Bin NBS reference materials and fertilizer materials has been described by Nielsen and Schmidt (B10). Huang and Huang (BI I) have used short-lived radionuclides produced by neutron irradiation to study impurity profiling in mixed diffusion systems. Parry (BIZ) has compared a planar intrinsic Ge detector to a coaxial Ge(Li) detector for the measurement of short-lived radionuclides. Of 44 elements studied, only Br, Rh, Nd, and Nb exhibited improved sensitivity by measurement of X rays or low-energy y-rays with the Ge planar detector. Data for reference rock samples are also presented. 44R

ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988

James and Oyedele (B13) and James (B14) have used the TRIGA research reador at Texas A&M University to produce fast transient reactor pulses by pneumatic ejection of the transient control rod upward to a preset distance. Pulse shape variations (B13),the design and constructionof a rapid sample transfer system (B13), and enhancement factors for INAA using the pulse technique (B14)are discussed. It was concluded that enhancement factors exceed unity for product radionuclides with half-lives shorter than 42 s. The technique was tested by analysis of several environmental samples and reference standards. Grass (B15) used short-time steady-state and pulse irradiations to determine U (b delayed neutron counting), B (by measurement of 20-ms gB), Au (after enrichment on C and measurement of 7.8-s IWmAu), and Na (by measurement of 20-ms %Na) in standard reference materials and environmental samples. Other than the review by Spyrou (A35) referenced previously, only a few references to cyclic INAA were found for the current review period. Al-Mugrabi and Spyrou (B16)have considered the techniques required for the optimization of the signal-to-noise ratio in cyclic activation analysis. Input to a program for simulation and optimization of a y-ray spectrum is derived for a sample irradiated in the cyclic mode with consideration given to the photopeak, Compton continuum, single and double escape peaks, and bremsstrahlung radiation. By use of the program, sensitivities and detection limits of the nuclides of interest can be deduced. Papadopoulos (B17)has described a new activation technique based on cyclic activation combined with intermediate temporary sample storage and special data processing for INAA determination of uranium. Grass (B15) used repeated analyses of subsamples of feldspar in determining Na by measurement of 20-ms 24mNa. In addition to the reviews by Garg and Batra (A39) and Shtan et al. (AN),several groups have explored the application of isotopic neutron sources to INAA. Nascimento and Simabuco (B18)used a 21.1-pg 252Cfsource for evaluation of mineral supplements for animals. Krishnan et al. (B19) have used two 100-pg 252Cfsources to determine Ca in vivo in rats and human hands. Nomai et al. (B20) have described procedures for determining trace impurities in minerals by INAA with low neutron flux irradiations. Interest in single comparator standardization methods in INAA has continued to the current review period. The popular k,-standardization method is essentially an absolute standarhtion technique based on the use of the fundamental equation of activation analpis. Occasionally unreliable nuclear data are replaced with a compound nuclear constant, KO,which has been determined for most elements with an accuracy of 3-5%. De Corte et al. (B21) has discussed the accuracy and applicability of the k,-standardization method with reference to relevant nuclear data, a non-1/E epithermal flux distribution, counting parameters, nonconstancy of the flux during irradiation, and related factors. Other papers from the same research group a t the Institute for Nuclear Science, Gent, Belgium, have presented a program for ko-method data reduction and techniques for detector efficiency calculation (B22), have considered the traceability of the method for both routine analysis and certification work (B23),have provided improved nuclear data on 94Zrand 96Zrfor use in neutron and have redetermined the half-life of 97Zr metrology (B24), to be 16.744 f 0.011 h (B24). Hien et al. (B25) have determined k0,*" factors for 10 elements with thermal neutrons in a reactor column. Feng (B26)and Feng et al. (B27) have considered R-matrix and k-matrix elements to express correlations among various elements that may be used in monostandard approaches to INAA. Koyama et al. (B28)used U, Sb, Cr, Co, and Lu as monitors in evaluating the neutron spectrum. Kazachevskii et al. (B29)used nichrome wire as a comparator, while Kim et al. (B30) used either Au or Co as a single comparator in the analysis of a number of rock standards. A monostandard program used with a Commodore computer and analyses of 15 E tian granite rock samples for 21 elements by the monost%%ud method have been reported by Zaghloul et al. (B31). Nelson (B32) has developed a complete INAA program for a PC-type microcomputer based on use of the monocomparator method. G b and co-workers at the University of California, W e , have published a number of papers on advance predictor programs for INAA (B9, B33-35). These programs take into


account nuclear pro rties and contributions of the Compton continuum from algignificant neutron-induced y-emitting radionuclides to provide advance estimates of detection limits and optimum irradiation, decay, and counting conditions for INAA of complex matrices. Obrusnik and Eckschlager (B36), Zhang et al. (B37),Burgess (B38),and Burgess and Hyumbu (B39) have all published predictor procedures for the optimization of adjustable parameters in INAA. Zhang also reports new data for a number of NBS and IAEA reference standards. Detection limits and precision in a variety of irradiation and counting regimes have been considered by Egan (B40),and a general consideration of detection limits and the effect of interferences on these limits has been published by Naumov et al. (B41). A wide variety of INAA software has been written for miniand microcomputers. Bothe (B42)described a basic program for calculating elemental concentrations, and Grossman and Baedecker (B43) used graphical procedures to control the analysis of selected photopeaks and evaluate detector performance in the analysis of geological matrices. Kennedy et al. (B44) developed an activation analysis system for shortlived radionuclides based on an IBM-PC coupled to a Canberra Series 80 multichannel analyzer. This system included automatic dead-time correction. Nieschmidt (B45) has described an INAA system based on use of a VAX computer which includes corrections for random and coincidence summing and finite sample size corrections at close geometries. Additional papers dealing with computational aspects of INAA include software for data collection and processing of y-ray spectra (B46-51), separate Compton-background determination in INAA (B52),anti-Compton y-ray spectrometry (B53, B 4 ) ,and the resolution of two radionuclides with overlapping y-ray energies based on half-life differences (B55). Heydorn ( B 6 )has considered quality assurance in neutron activation analysis. He points out that NAA does not have to rely on other reference materials to ascertain the quality of the analytical results. The characteristics of the method make possible the estimation of uncertainties of individual results from basic a priori assumptions. Minimization of blank values in the INAA of biological materials has been addressed Abrasions . of stainless steel, titanium, and by Lux et al. (B7) quartz scalpels, ball mill homogenization of samples prior to irradiation, and contamination of quartz vials that pass through a RNAA procedure are among the topics discussed. Gawlik et al. (B58) described a procedure in which biological samples are enclosed in thin-walled quartz vials, immersed in liquid nitrogen, and irradiated for up to 14 da s. The method is claimed to minimize losses of Fe, Zn, and ge which or oven-drying of samples may be associated with freezeprior to enca sulation for irra iation. Problems associated with postirraliation weighin of biological sam les have been discussed by Kiem et al. (&9). Primary antsecond-order nuclear interferences,mainly in geological matrices, have been evaluated by several groups (B60-63). Sampling constants as related to the establishment of a otential reference standard have been investigated by Hey&rn and Damsgaard (B64). In the area of instrumentation for INAA, Wogman and Lepel have described the use of a 252CfBUfueled subcritical neutron multiplier for activation analysis (B65).A flux density s-l was attained. The system was of approximately lo9n used with Ge(Li) and HPGe detectors and anticoincidence shielding. Over 65 elements were measured in environmental samples with this system, in some cases down to the sub-pg/g level. A method for the reduction of @-interference (bremsstrahlung) in y-spectrometry of geological samples has been presented by Garmann (B66). New y-ray spectroscopy systems for INAA are described by Suzuki and Hirai (B67) and Suzuki et al. (B68). Multiparameter coincidence spectrometry has been used for INAA of Sn and Ir in ultrabasic rocks by Meyer (B69). One of the developments in INAA that we will be hearing much more about in the future is the use of cold neutron beams. Neutrons are passed through a cold source in the reactor and are guided down beam tubes to an irradiation location that may be tens of meters distant. The lower neutron energies result in higher effective cross sections, and the remote location of the irradiation facility together with use of guide tubes means that fast neutron and y-ray backgrounds are greatiy reduced. The principles of cold neutron INAA have

been discussed by Lindstrom et al. (B70). Although the main use of the method will be in prompt gamma neutron activation analysis, it has also been used for irradiation and conventional delayed activity detection to characterize pigments in a Rembrandt painting (B71). This work used the cold neutron guide tubes of the reactor in Grenoble and, with a scanning device, measured activities by use of successive autoradiographs. In another unique approach to INAA, etchable damage tracks in detector materials left by charged particles that are emitted following thermal neutron capture reactions are detected (B72). The most common applications are the determination of B in metals and coatings and U in O-ring seals. Both mapping and quantitative determination are possible. The spatial resolution for mapping is approximately 25 pm. Lithium, N, and possibly S and 0 can also be determined. A final unusual application of INAA involves the use by Clarke et al. (B73) of mass spectroscopic measurement of 3He (from the decay of 3H) and 4He gases produced by neutron-induced reactions on 6Li and log. Interference reactions on N, C, and 0 are serious where the fast neutron (>0.2 MeV) flux is high, but the thermal column of the heavywater-enriched NBS Reactor (Gaithersburg, MD) was used successfully for determination of Li and B in human blood, blood components, and several biological reference materials. Suitable corrections for other thermal-neutron (np) reactions associated with the biological matrix must be taken into account. Selected applications of INAA are presented in Table 11. The listing is not exhaustive but provides references in a variety of scientific disciplines that the reader may easily find in major international journals. References to less common journals or proceedings are included only for those categories where the literature is limited. 2. Reactor Epithermal Neutron Activation Analysis (ENAA). A number of research reactor facilities now have shielded irradiation sites installed in the reactor core for ENAA. Descriptions and evaluations of Cd-shielded irradiation facilitieshave been published by Holzbecher et al. (B171) and Williamson et al. (B172). However, many analysts still encapsulate each individual irradiation unit in a thermal neutron filter and remove the filter material after the irradiation. Due to the high levels of activity induced in the fiiters, the latter procedure does not have much apped to the analyst, or to reactor operations personnel. Future applications of ENAA will probably be based on use of fixed, in-core irradiation channels. A comparison of Cd, B (as B4C), and Cd+B filters for ENAA sample capsules has been presented by Okada et al. (BI 73). Approximately 50 radionuclides were detected with a Ge(Li) detector after 2-5-min reactor irradiations. Sensitivities of Ag, Au, I, In, Se, Sm, Sn, and Yb were improved by use of the Cd filter, and As, Ba, Br, Mo, Ni, Rb, Sn, Sr, and Zr sensitivities were improved by use of either a B or a B+Cd filter. Problems associated with the use of B4Cthermal neutron filters in ENAA have been discussed by Chisela et al. (B174). Cooling of both sintered and powdered B4C filter confiiations during the irradiation is desirable. It was noted that the accumulation of the 'OB(n,a)'Li reaction products in filters containing B may limit the reuse of the filters in subsequent irradiations. Chisela et al. (B175) have also described the use of high-purity graphite as an alternative to polyethylene for primary sample containers in ENAA. Tian (BI 76) has reviewed definitions of generalized advantage factors and examined factors leading to the optimization of irradiation conditions in ENAA. Zaghloul et al. (B177) described an ENAA a proach based on use of a monostandard (Au) and small 8 d sample covers to minimize problems associated with the use of large Cd irradiation capsules. Several groups have also considered corrections to the resonance integral and characteristics of the epithermal neutron spectrum as applied to ENAA (B178,B179). Tokay et al. (B180)reported a technique for reducing interferences in ENAA, based on the existence of nonoverlapping resonance peaks in the neutron absorption cross-sectionsof nuclides in the analytical sample. Interferences were reduced by use of appropriate neutron filters. New published applications of ENAA are few in number. ENAA of biological materials with use of a B4C or BN filter has been reported by Chisela and co-workers (B181-B183). Coal analyses by ENAA have been described by Bellido and ANALYTICAL CHEMISTRY, VOL. 80, NO. 12, JUNE 15, 1988

45 R


Table 11. Selected Applications of Instrumental Thermal Neutron Activation Analysis Archeology bone ceramics, pottery coins, jewelry glass metal sculpture

paintings raw material, rocks, soil statistical methods Environmental Science and Related Fields animals, birds, insects, fish atmosphere, dust, aerosols foods, crops general ground water, rain melanins plants, trees seaweed, algae tobacco and tobacco products Forensics shooter identification shotgun pellets Geology, Geochemistry fossil fuels, coal, coal products, petroleum leteorites minerals ocean nodules rocks

sediments soils, glacial till Industrial Products and Applications electronic materials fertilizers and related raw materials fissile materials detection high purity materials municipal waste pharmaceutical products Medicine, Human Tissue, Dental Specimens blood bone brain

colon dental fillings

fetus hair liver

lung mineral availability muscle nails placenta urinary stones urine Other

educational laboratory

B74 B75-82 B83 B84 B85-87 B71, B88 B89-93 B94 B95-101 B102-104, B117 B3, B18 B105-106 A44-45, B107 A31, B108-110, B117 Blll B112-117 B118-119, B143 B120-121 B122 B123 B124-126 A31, B62, B66, B128-129

B130 B131 A40, B48, B63, B66, B69, B132-138 B134, B139-143 B144-146 A83, B147 B5. B148 B149 B150 BE1 B152 B58, B73, B153-155, B169 B19, B74, B156 A31, B157-158, B169 B159 B160 B161 B155, B162-163, B169 B58 B154, B164 B1 B57, B165 B154, B169 B166 B167 A34, B154, B168 B5, B170

exDeriments

Arezzo (B184,B185) and Suzuki et al. (B186).Atalla et al. (B187)used both thermal and epithermal NAA to determine 21 elements in geological materials. 3. Prompt y Neutron Activation Analysis (PGNAA) and Neutron Depth Profiling (NDP). NDP is grouped here with PGNAA since both depend on neutron activation and measurement of radiations (PGNAA) or particles (NDP) that are romptly emitted. There been a significant increase in activity in the field of PGNAA since our last review. Applications of PGNAA in the areas of on-line and in vivo analysis are now common. Lindstrom et al. (B70)have discussed the advantages of cold neutron beams in PGNAA and described experiments conducted with the cold neutron facility a t the FRJ-2 (DIDO) reactor of the Nuclear Research Center, Juelich. We expect 46R

ANALYTICAL CHEMISTRY, VOL.

BO, NO. 12, JUNE 15, 1988

to see many applications of cold neutron PGNAA published before our next review. Both prompt neutron and prompt charged-particle activation analysis have been considered as techniques to obtain remote analyses of extra terrestrial bodies (B188).PGNAA of expected planetary constituents were measured with neutron-generatorand cyclotron produced neutrons, with energies up to 78 MeV. Hlavac and Oblozinsky (€289)have considered the time and energy spectra of y-rays emitted after the inelastic scattering of 14.6-MeV neutrons in bulk concrete samples. Nicolaou et al. (B190,B191) have considered target homogeneity, beam uniformity,and target-detector solid angle for in vitro and in vivo PGNAA. The technique of y-ray emission tomography employing neutron capture prompt y-rays has been used to obtain a two-dimensional reconstruction of elemental distributions in a sample (B192). In the area of PGNAA on-line analysis, Watterson (A51) has reviewed a number of techniques for ore analysis, including PGNAA. Votava and Kubant (B193)have developed a method for on-line determination of the ash contents of coal, and Arai (B194)has described a continuous coal analyzer based on the use of a za2Cfsource. Yuan et al. (B195)have used a Monte Carlo simulation model to predict unscattered y-ray intensities in the analysis of coal in conveyor-belt geometry. Rainbow (B196)also describes a Monte Carlo simulation for a PGNAA iron ore analysis system. Weiss and Gartner (B197) have developed a prompt-y system for control of raw mix composition in cement planta. Chang and Chung (SI981have reviewed applications of PGNAA for in vivo clinical diagnosis. Knight et al. (B199) determined total body N and C1 in cadavers, and Chang et al. (B200)determined Cd in kidney by using in vivo PGNAA. Ellis and Cohen (B201)have described the in vivo neutron activation analysis (IVNAA)facilities at Brookhaven National Laboratory. Scott and Chettle (BZ02)discuss a variety of techniques for in vivo analysis with special attentiation to Cd and P b determination. Amo other biological applications of PGNAA are elemental an2yses of B in human lacenta (B166),B in teeth and bone (B203), and H, C, N, S, C1, and K in blood (B204). In geological studies, several laboratories report PGNAA determinations of selected rare-earth elements in geological samples and USGS reference standards (B205-208).Several of the latter (B207,B W ) also report B analyses. In an unique application, Bower et al. (B209)report the determination of water by PGNAA in 19 USGS rock reference standards. The PGNAA water analyses compared favorably with analyses done with a commercial coulometric water analyzer. PGNAA B211) has been applied to sediments by Spychala et al. (B.210, and to oceanic nodules by Grigor'ev et al. (B212).Underwood and Petler (B213)describe a downhole logging tool that uses a 5-Ci "'Am-Be source for use in measuring sulfur. Riley and have determined B in borosilicate glasses Lindstrom (B214) by PGNAA. Nishikawa et al. (B215)have reported a novel technique based on PGNAA to measure components inside a high-temperature furnace. Evans et al. (B216)and Livingston et al. (B217)describe the use of PGNAA for in situ diagnosis of the condition of buildings and studies of historic building deterioration. Gordon and Olmez (B103)used PGNAA and other analytical techniques to study atmmpheric aerosols in the Asia-Pacific area. Finally, Downey and Sandy (B218)have published a radiochemism laboratory experiment based on the PGNAA determination of H in solvents, using a 252Cfneutron source. There were only a few publications dealing specifically with NDP during the current review period. Downing et al. (A25, B219)reviewed analytical applications of NDP and Maki et al. (B220)published information on methods used for deconvolution of NDP spectra. 4. Fast Neutron Activation Analysis (FNAA). The use of Cockroft-Walton accelerators to produce 14-MeV neutrons by the 3H(d,n)4Hereaction is still the most common method of FNAA. Reviews of the field have been noted previously (A23,A24). In addition, the new two volume CRC Handbook of Fast Neutron Generators by Csikai (A3)is a valuable source of data and references in the field, Pepelnik (B221)has published a comprehensive study of 14MeV sensitivities and analysis interferences. Kondo (B222) examined the suitability of cyclic activation techniques for FNAA. He reports sensitivities for 28 nuclides representing

8,


17 different elements. Cecil and Nieschmidt (8223)considered the effect of tritium buildup on deuterium targets used in FNAA methods based on the 2H(d,p)sHreaction. A sealed high-Fower neutron generator tube capable of producing 6.5 X 10’ n/s by the 3H(d,n)4Hereaction has been described by Schmidt (B224). Experimental measurements of fast neutron cross sections have been published by. Pepelnik et al. (B225) and Torii et al. (B226). Analyses of air-dust samples (B227),rocks and ores (B228, B229). and soils iB230) have been recentlv reDorted usina conventional 14-MeV FNAA. Prompt ray detection foc lowing 14-MeV neutron activation has %;en used for both batch and in situ analyses for major elements in coal and for hydrocarbon prospecting (B231-233). Ehmann et al. (B234) have used several different 14-MeV FNAA techniques to determine the organically bound oxygen content of coals. In industry, FNAA has been used to determine heavy metals in aerosols enerated in the working environment of welders (B235),to etermine the Al content of glasses (B236), to measure the thickness of Si films on glass plates (B237), and to automaticall analyze fertilizers and foods for N, P, K, and Si (B238). unique application of 14-MeV FNAA published by Mitchell et al. (B239)uses proton track counting of protons from the 14N(n,p)14Creaction in the determination of the N distribution in polymers. The tracks are registered in cellulose nitrate detectors during exposure of the polymers to 14-MeV neutrons. Both bulk and surface N levels were determined. 5. Charged-Particle Activation Analysis (CPAA). Reviews of CPAA for the determination of light elements have been published by Shigematsu (A26),Hoste and Strijckmans (A27),Nozaki et al. (A%),and Strijckmans and Vandecasteele (A29). CPAA techniques for determination of light, medium, and heavy elements in metals, semiconductors, rocks, and environmental samples have been reviewed by Vandecasteele (A30). Sisterson and Koehler (B240)discuss the use of CPAA to achieve very precise localization of the activation volume within a target. They describe measurements of whole-body Ca in animals and the determination of the Ca/P molar ratio in small chemical and biological samples. The feasibility of using CPAA to determine blood flow in the eye is also assessed. Isotopic determination using proton-inducednuclear reactions followed by fast (200 MHz) j3 counting has been described by Von Wimmersperg et al. (B241). Oxygen and B determinations and potential applications to the measurement of N and C are discussed. Fukushima et al. (B242) have evaluated irradiation conditions, chemical separations, and countin methods in order to optimize determination of C, N, and by CPAA. Potential errors due to heating of rock and environmental samples by 23-MeV protons during CPAA have been considered by Wauters et al. (B243). Irradiation under a He atmosphere with a minimum beam intensity was recommended in order to avoid systematic errors due to volatilization. Diaco et al. (B244)have studied the determination of Be using an l80ion beam. Friedli et al. (B245) report the use of l80ion beams to determine Be and S by the 9Be(l8O,2a)lgOand azS(180,t)47V reactions. In a unique approach, Pham et al. (EM)used a 21’?Poa-particle source to determine Al, F, and N by CPAA in a variety of samples. Barrandon (B247)used both protonic and helionic CPAA to investigate ancient metallurgical objects. Yagi and Masumoto (B248)have determined As,Ca, Fe, Mo, Sr, Ti, V, Zn, and Zr in biological materials by using an internal standard method. The same laboratory also reports determination of Ca, C1, K, and P in blood serums by using a-particle CPAA (B249). Several recent publications have applied CPAA in environmental studies (B250-252). In the industrial area, CPAA has been used in the analysis of fly ash (B253),semiconductors (B254, B255), metals and alloys (B255-253, machine parts (B258-260), optical fibers (B261),and various solid-state materials (B262). 6. Instrumeatal Photon Activation Analysis (IPAA). As was the case for our 1986 fundamental review, few new publications on the methodology of IPAA have appeared in the literature. This is undoubtedly due to the fact that few analysts have access to the high-intensity photon sources required for the technique. Instrumental photon activation has been compared to other nuclear methods for the analysis of high- urity metals and reference materials by Segebade and SchmidE (B263). It was found that IPAA was particularly

d

2

8

suitable for analysis of light elements, T1 and Bi, and generally yielded results of equal quality to NAA where adequate sensitivity was available. Interferences in IPAA of fission fragments resulting from photofission of U and Th have been studied by Davydov et al. (B264). It was pointed out that these.inferences can be important sources of error in the determination of Au and Ag. A method of calculating the effect of the photofission contribution to recorded activities is also presented. Photon activation methods have been applied to the in vivo determination of total-body 0, N, and C by Ulin and coworkers (B265,B266). In these studies, positron-emittin 150, llC, and 13Nradionuclides were induced by an intense keam of X-rays from a 45-MV betatron. A computer curve-fitting algorithm was used to resolve the contribution from each of the separate product radionuclides. Experiments were conducted with both phantoms and animals. Hollas et al. (B267) describe an interesting application of IPAA based on counting delayed photofission y-rays to detect heavily shielded fissionable materials. Bremsstrahlung photons produced by 10-MeV electrons from a small linear accelerator were used. Delayed y-ray spectra from natural Th, 93% enriched 236U,natural U, and 93% enriched 239Puwere found to be distinctive. In other applications, IPAA has been used in analysis of blood (B204),environmental samples (B268-270, B272), airborne particles (B271),rocks (B272-275),tektites (B276),soils and sediments (B277-279),and water standards (B280). Sato and Kato (B281)describe the IPAA determination of Br, Cd, Cu, Pb, and Zr in human kidney samples by using a LEPS detector to measure X-ra and low-energy y-rays from -Br, lo7Cd,64Cu,203Pb,and i? Zr. 7. Radiochemical Neutron Activation Analysis (RNAA) and Preconcentration Methods. Traditional RNAA involves either group or specific-elementpostirradiation separations to eliminate spectral interferences and lower base-line activity levels. In this approach, the NAA advantage of potential freedom from reagent and laboratory contamination is still exploited, but the analyst must often handle highly radioactive materials. There appears to be a growing recognition that purely instrumental NAA cannot meet all of the analyst’s needs. The increased availability of high-purity reagents and clean-room facilities has encouraged the development of new preirradiation separation or concentration procedures that can minimize the handling of highly active samples. These preirradiation approaches have resulted in a variety of new “hyphenated NAA techniques”. Derivative activation analysis represents still a different radiochemical approach but is not based primarily on the need to eliminate interferences. RNAA and preirradiation separation and concentrationtechniques will be reviewed in this section, along with a few procedures for separating naturally occurring radionuclides. Derivative activation analysis has been discussed in section B1 and has recently been reviewed by Ehmann et al. (A31). Pietra et al. (A32) have published a very useful review of 22 radiochemical separation procedures for RNAA of environmental and biological samples. The procedures are based on separation of the elements into groups which allow the determination of up to 50 elements in a sample or are designed to separate single elements. Another review of radiochemical separation methods by Moebius (A33) discusses problems associated with working with very dilute solutions and gives examples of separation procedures for transuranium elements. Blotcky and Rack (A34)have reviewed preirradiation treatment and storage of urine samples. They conclude that Teflon and polyethylene containers are suitable for storage, and the use of preservatives or freeze-drying would depend on the specific elements to be determined. Sampling and handling procedures prior to irradiation have been considered by Parr (B282). Parr also discusses losses of volatile elements such as As,Hg, Sb, and I during sample dissolution procedures prior to application of radiochemical separations. Losses in preirradiation oven ashing of biological samples have been evaluated by Tonouchi et al. (B283). The loss of Cs from rice was noted to be as high as 30%. The use of substoichiometry in RNAA has been described by Turel (B284). An application of the technique to the determination of Au is also presented. A new composite ion exchanger comprising powdered hydrous Sb205 implanted into a matrix of phenol-sulfonic-formANALYTICAL CHEMISTRY, VOL. 00, NO. 12, JUNE 15, 1988

47R


Table 111. Selected Applications of Preconcentration or Radiochemical Separation matrix

elements determined

methodology

ref

Biological Samples general blood crops, food SRMs

placenta hair

As, Hg, Sb, Se Cd, Co, Cu, Se, Zn Ag, Au, Cd, Hg, Zn Cd, Co, Cr, Cu, Mn, Mo Cd, Co, Cr, Cu, Mn, Mo As, Cr, Mo, Sb, Se may As, Cr, Mo, Sb, Se Cu, K, Mn, Mo, Rb, V La, Eu, Tb many 36 elements Cd, Co, Cr, Cu, Mn, Mo As, Cu, Se, Zn

pre-irr. collection of gases extr. with 4-NDP and Na-DDTC post-irr. ion exch. ion exch. ion exch. post-irr. inorg. ion exch. NAA-gas thermochromatography post-irr. inorg. ion exch. resin solvent extr. substoichiometry pre-irr. sepn. of Na pre-irr. sepn. of Na ion exch. post-irr. ion exch.

B294 B295 B296 B297 B297 B298 B299 B298 B300 B301 B302 B302 B297 B303

Environmental Samples aquatic materials particulates in rainwater plants, etc.

Cd, Cu, Hg, Se, Zn many Am, Cm, Np, Pu

general meteorites, lunar samples

many Cd, In, T1 lanthanides Au, Pd, Pt Ag, Au several Ir, Os, Pd, Pt, Rh, Ru Au, Ir, Pd, Pt Ag, Au, Ir, Pt, Re Pt group elements several Ag, Au, Ir, Pt noble metals rare-earth elements

post-irr. sepn. preconcentration with Chelex-100 resin ashing, solvent extr., direct counting

B304 B305 B306

Geological Samples

noble metal ores

rocks

Yb aldehyde resin has been developed by Bilewicz et al. (B285) for the removal of %Na in the RNAA of biological materials. Distribution coefficients for 18 metal cations on amphoteric resin Retardion llA8 have been determined by Aldabbgh and Dybczynski (B286).Miyata et al. (B287) reported the use of a poly(tetrafluoroethy1ene)porous membrane in a postirradiation radiochemical procedure for the determination of Cu, Mn, and Zn in brain from ALS patients. Molecular activation analysis is a technique in which preirradiation separations allow the characterization of the molecular form of an element. The technique hm been described by Opelanio-Buencamino (B288)and used by Blotcky et al. (B289)for simultaneous determination of selenite and trimethylselenonium ions in wine. The use of an activable tracer in biological studies is described b Snapka et al. (B290). Following separation of nucleotides gy TLC and proteins by polyac lamide el electrophoresis (PAGE), ands containing activa8e nuclicfss such as 66Mn,lS1Eu,or I%y are bound to the separated molecular species. The compounds are then irradiated with neutrons and detected by autoradiography. Stone et al. (B291)have presented procedures for characterization of biological macromolecules by PAGE followed by INAA to detect metals normally associated with the proteins. Jayawickreme and Chatt (B98)used INAA to determine protein-boundtrace elements in separated subcellular fractions of bovine kidneys. This work was previously referenced in section B1, but the paper also contains information on trace element concentrationsof common reagenta that can be useful to analysts using preirradiation chemistry. Duke and Smith (B292)have coupled a preirradiation group separation procedure for rare-earth determination in rocks with yield determinations by isotope dilution maas spectrometry. In an unusual application, Theis and Englert (B293)have developed radiochemical separations with extremely high decontamination factors in order to measure simulated levels of long48R

*


thermochromatographic sepn. post-irr. column chromatography precipitation and ion exchange liq. chromatography fire assay preconcentration preconcentration in a chelating resin fire assay preconcentration preconcentration in NiS matte sublimation preconcentration post-irr. extr. post-irr. thermochromatography fire assay preconcentration chromatography pre-irr. sepn., precipitation post-irr. sepn. ion exch. substoichiometric extr.

B307 B308 B127 B309 B310 B311 B312 B313 B314 B315 B316 B317 B318 B321-323 B319-320 B324

lived cosmic-ray-induced radionuclides in high-purity elemental foils. Other selected applications of RNAA and preirradiation concentration or separation are presented in Table 111.

C. ISOTOPE DILUTION ANALYSIS (IDA) The techniques of radioimmunoassay (RIA) and radioreceptor analysis (RRA) are still the most common applications related to IDA. Consideration of the extensive literature associated with these techniques is beyond the scope of this review, and we refer the reader to other reviews (A6M7) listed in Table I. The sub- and superequivalence method of isotope dilution analysis (SSEIDA) was mentioned in our previous review and continues to attract some interest. In this method one series of solutions is prepared in which the individual solutions contain the same amount of sample and radioactive spike but are isotopically diluted with increasing amounts of stable carrier. A second set of solutions contains no stable carrier, but each solution contains a multiple amount of both aample and radioactive spike in the first series. With all solutions first brought to the same volume, a substoichiometricamount of reagent is added to each solution, the products are isolated, and the activity ratios in the two series vs carrier added in the first series are plotted and used to determine the amount of the element of interest in the original sample. A number of variants of the method are possible. Yoshioka et al. (CI) report a new SSE-IDA for the determination of antimony using a redox reaction. Prikrylova et al. (C2)have compared the advantages and disadvantages of different graphical evaluation procedures for SSE-IDA and a related approach. Klas et al. (C3-5)have evaluated the theoretical error associated with several variants of this unique method. A study by Fischer (C6)of the action of microwaves on the dissolution of geological materials in pressurized vessels


containing acid mixtures showed that microwave dissolution allowed equilibration of isotope spike and sample for IDA in almost one-fiih the normal dissolution time. Kostitayn and Zhuravlev (C7) have discussed the sources of random errors in IDA. They have also examined the use of mixed tracers of daughter and parent elements in IDA. Pratt (CB) has described a new approach to stable s ike IDA in which a known mass of a 2H-labeled compoun is added to a serum sample. HPLC is used to separate the endogenous compound from ita 2H-labeledform. After separation, the two forms of the analyte are quantfied by using conventional methods such as RIA. The ratio of the amounts of the two forms of analyte is used to calculate the amount of the unlabeled compound in the original serum sample. Applications of the technique to various types of problems are discussed. A chemical IDA approach to accelerator mass spectrometry (AMS) as applied to radiocarbon dating of derivatized amino acids has been developed by Gillespie (C9).Beyrich et al. (ClO)describe a interlaboratory measurement evaluation program to determine the elemental and isotopic contents of input solutions to nuclear material reprocessing plants. In this program, elemental analysis for U and Pu was by isotope dilution mass spectrometry. The authors claim that the results confirm a considerable improvement in IDA over the decade since the previous interlaboratory experiment. Additional selected applications of both stable and radioactive IDA are presented in Table IV.

a

D. D I R E C T C O U N T I N G OF NATURAL RADIONUCLIDES The counting of natural and heavy radionuclides finds primary application in the fields of environmental research, geochemistry, and cosmochemistry. The application of direct a-particle spectrometry and selective radiochemical methods to the determination of plutonium and transplutonium elementa in environmental samples of rainwater, seawater, and seaweed has been reviewed (011, and low-background y-ray spectrometry has been employed in the determination of uranium, radium, thorium, and potassium in soils (02) and sediments (03,04). Kataoka and co-workers ( D 2 have presented a method for the rapid determination of 6Ra in environmental materials. The w e of perturbed y-y directional correlation measurements to obtain information about the chemical environment of molecules in environmental samples has been discussed (06). This technique, which promises a wide range of applications, has the advantage that the measurements are noninvasive; however, specific activities greater than those commonly found in natural materials are typically required for speciation. For in situ geophysical investigations, the measurement of gross and spectral characteristics of naturally occurring ra. cosmochemical diation has been reviewed (07)Traditional applications of direct counting are typified by the reported determination of radionuclides in a chondritic meteorite with low-level y-ray spectrometry (08). In more venturesome applications, the possibilities of determining the elemental compositionsof the surfaces of small bodies in the solar system such as asteroids, planets, or moons by y-ray spectroscopy in future planetary exploration missions have been examined (09,DlO). Prompt y-ray spectra of planetary constituents have been measured in laboratory experiments (091, and calculations (010) have been performed to examine the feasibility of this concept.

E. CHARGED-PARTICLE R E A C T I O N ANALYSIS Elemental analysis with charged-particle beams in the megaelectronvolt energy domain has emerged as one of the most fruitful applications of nuclear methodology, and the literature in this area continues to grow at an impressive rate as more ingenious approaches to specific problems are developed. At the same time, this is a rather mature field where the focus tends to be more on the application of these techniques, and novel advances in the methodology occur more grudgingly. Since the nature of the desired analysis often depends critically on the t e of material which is to be characterized, we have provi ed references to many specific applications in Tables V, VI, and VII. Particle-inducedX-ray emission (PME) has not been included in this review for two reasons: (a) while using accelerated charged-particles and

YB

Table IV. Selected Applications of Isotope Dilution Ana1y ais

element/compound of interest

methodology/matrix

ref

Biology/Medicine DNA

SSE-IDA using an enzyme reaction stable-IDA, negative ion MS/CSF, plasma, urine, amniotic fluid 60Cr,NAA-IDA stable-IDA/amniotic fluid, urine stable-IDA/blood serum

pipecolic acid blood volume isovalerylglycine methacetin

c11

c12

C13 C14 C15

Environment Sr substoich.-IDA/seaweed Fe, Ni, Cu, Zn, Ga, Rb, stable-IDA/NBS 1575, pine Sr, Cd, T1, Pb needles Ni, Cu, Sr, Cd, Ba, T1,Pb stable-IDA, ICP-MS/nonsaline natural waters

C16 C17 C18

Foods film plasticizer aroma compounds

stable-IDA, GC-MS/variety of foods stable-IDA,wheat and rye bread

Cr, Ni, Zn, Sr, Mo, Cd, Sn, Sb, T1, Pb, U Pb, T1 rare earths

stable-IDA, ICP-MS/marine sediments stable-IDA/meteorite stable-IDA/meteorite

c19 c20

Geology c21 c22

C23

Industrial 287Np Am,Pu, u T1

MS/spent nuclear fuel MS, reverse phase chromatography/spent nuclear fuel SSE-IDA/commercial 2ovT1 samples

c24 C25 C26

Laboratory Experiment cs

lS7CsIDA, precipitation

c27

nuclear methods of detection, PIXE does not involve nuclear reactions, and (b) this topic is reviewed elsewhere, as well as in this series of reviews. We have considered what is often referred to as nuclear reaction analysis (NRA) in three categories-PIGE, RBS, and other charged-particle-induced nuclear methods. These methods are often employed simultaneously by simply adding additional detection capabilities, and, with microbeams, each can be utilized in nuclear microprobes, the final topic of this section. 1. Particle-Induced y-Ray Emission (PIGE). Prompt y-rays emitted following a charged-particle-induced nuclear reaction are detected in PIGE, which is also occasionally referred to as PIGME or PIPPS, analysis. PIGE finds its greatest application in the analysis of light elements that are difficult to determine with PIXE and, since y-rays are detected, is capable of distinguishing between isotopes of an element. Considerable attention has been devoted to the analysis of biological materials by PIGE (often combined with PIXE) analysis (A54, El). Problems arising from the effects of changing current densities and sample chargin in the analysis of thick biological samples under vacuum has k e n considered (E2),and a target-moving system was developed for suppression of charge-induced yield increases (E3). Although there is a limit to the total beam charge which may be safely de osited on a moving biological target, the duration of the sa& bombardment has been shown to be sufficiently long to allow the accumulation of meaningful statistics. The advantages and drawbacks of external-beam methods as an alternative approach for biomedical work have been discussed ANALYTICAL CHEMISTRY, VOL. 60, NO. 12, JUNE 15, 1988

49R


Table V. Selected Applications of PIGE, PIGE/PIXE, and Other Methods of Charged-Particle-InducedNuclear Reactions PIGE Analysis archaeology pottery, glass, porcelains biology biomedical samples biological specimens hair, spleen, liver, lung, bone geology Li in minerals lunar soils F in geological materials miscellaneous Na in aerosols H atoms in solids, W crystal 0 in Si wafers

Ell A54 E3 E12 E9 E12 E14-17 E18 A89 E7

PIGE/PIXE Analysis archaeology pottery biology human colostrum, spermatozoa, teeth, follicular fluids, tree rings 'H and I6Nstable isotopic tracers phospholipid bilayers geology obsidian and desert varnish geological standards miscellaneous aerosols from volcanic plume alloys art paintings borosilicate glasses thick zeolites

E19 El E6 E20 E19 E21 E22 E23, E24 E25 E26 E27

Other Charged-Particle-Induced Nuclear Reactions aerosols alloys B implanted in Cu-(p,a) resonance reaction 0 in Sb-implanted Ag-(pp) reaction implanted metals and C-Th-C sandwich targets light elements in Au artifacts-(d,p) reaction artifacts and art objects glasses minerals superconductors-0 content by the (d,p) reaction

E120 E121 E122 E123 E124 E125 E125-127 E128 E129

(A54),and external-beam PME/PIGE analysis facilities with helium fluehing (E4)or air as the external gas (E5) have been described. The applicability of PIGE methods for the detection of stable isotopic tracers in biological materials has been studied (E6).The 16N(p,y)l%reaction was found useful for the detection of 16N,even a t the natural abundance level, and, for deuterium tracers, the 2H(12C,py)13C reaction was chosen because of its large cross section. While protons and a particles are commonly used in PIGE analyses, other charged-particle beams have been utilized effectively for special applications. Fu'imoto (A89) has reviewed the detection of hydrogen in sojids and provides an exam le of the most sensitive method, a recent measurement of h$Ogen atoms on the (100) surface of a W crystal by the lH(6N,ay)12Creaction. Oxygen has been determined by deuteron bombardment ( E n ,and Peisach and Gihwala (E8) report on unusual interference effects roduced when radionuclides formed under deuteron bomtardment decay to the same nuclear states as those excited promptly. References to a-particle source induced y-ray emission are also found (E9). In what should prove to be a very useful compilation, Raisanen and co-workers (E10)have determined absolute thick-target y-ray yields for elemental analysis by 7- and 9-MeV protons on various elements from Z = 3 to 82. Additional applications of PIGE can be found in Table V. 2. Rutherford Backscattering Spectroscopy (RBS) and Elastic Recoil Detection (ERD). Rutherford back50R

*


Table VI. Selected Applications of Rutherford Backscattering Spect&wopy alloys amorphous materials ceramics electronic materials microelectronic circuits electronic components glasses glassy polymers Br-implanted glass various glassy materials ion-implanted materials niobium silicon GaAs miscellaneous multilayered materials oxides and oxidation processes semiconductors single crystals thin films polymers films of pure elements inorganic compounds miscellaneous materials aerosols bones from Egyptian mummy coins electrochemical processes laser treated surfaces topaz stones

E55-57 E54, E58-60 E61, E62 A49, E63 E37, E64, E65 E66 E67 E52, E68-71 E72, E73 E74-76 E77, E78 E79-81 E82-86 E87-91 E92-94 E30, E95 E32, E96-98 E99, El00 E101-106 E107 E108 E109 E42, Ell0 E l l l , E112 E113 E114

Table VII. Selected Applications of Nuclear Microprobes archaeology white lead in paints artifacts biology biominerals botanical materials individual cells various organs biomedicine arteries blood cells and erythrocytes liver and pancreas skin teeth cosmochemistry interplanetary dust particles meteorites electronics geology coal fluid inclusions glasses and volcanic minerals various minerals materials science miscellaneous copper bells electrostatic column laser mirrors plutonium surface contamination on steel

E140 E132, E141 A100, A101

E142-144 E145-147 E134, E137, E148 E149-152 E153 E154, E155 E156-158 E159, E160 E161, E162 E163 E164 E132, E138, E165-167 E64, E168 E169 E170 E171 E132, E135, E172-174 E175-178 E179 E180 E181 E182

scattering spectroscopy has proven to be a powerful tool for the determination of stoichiometry, structure, thickness, and im urity concentrations of surfaces. RI3S is now in such wilespread use by solid-state physicists and materials scientista that it is usuall considered along with other routine surface analysis teciniques, and reviews describing this technique and its applications are abundant (A49, A90-93, A98, A99, A108). While protons or 4He ions are the most commonly used projectiles for RBS- and RBS-channeling studies (e.g., see ref E28-30), the feasibility of analyzing compounds containing


heavy elements with heavy ions has not gone unnoticed (E39, E3l). Special problems, such as beam-induced compositional changes of polymers during RBS analysis (E32) and contributions from the experimental appratus (primary particles of unknown origin or of lower energy than the nominal bombarding energy) to the low-energy background in RBS (E33), have recently been discussed. Knox and Harmon (E34)have described how it is possible to take advantage of non-Rutherford scattering to enhance the sensitivity of backscattering spectrometry for light elements. The ap aratus for RBS can be of varying degrees of complexity. &ark et al. (E35) have constructed a microcomputer-controlled wide range three-axis goniometer for RBS channeling ex eriments. Several authors have developed apparatus anfmethods for preparing thin films or inert substrates for RBS analysis (E36-39), and in situ analyses have become common (E40-42). The uncertainty in our knowledge of stopping powers is one of the major factors affecting the accuracy of RBS methods. The contributions of these uncertainties have been explored by Niiler (E43),while Mertens and co-workers (E44) have determined proton stopping powers in several metals by comparative measurements on identical targets in backscattering and transmission geometries. A comparative analysis of extended defect depth profiles in silicon determined by RBS, electron microscopy, and X-ray diffraction has been performed by Bentini et al. (E45)who found good agreement between the three methods, but emphasize the importance of precision stopping power data. Several computer codes for the analysis of RBS spectra have been described (E46-49). Doolittle (E47) has applied nonlinear least-squares techniques for multivariate fits of simulated spectra to experimental data and report that the algorithm has been incorporated as part of a package available for routine RBS analysis. The code developed by Eridon and Was (E48) was constructed to perform automatic iterative fitting of spectra using only the experimental spectrum and the parameter set defining the experiment. They report that this code, which may be used to analyze samples containing two to five elements, is fully automatic and does not require constant user intervention. Limitations on the code and its use include the precise knowledge of the relevant experimental parameters used as input and complete specification of all elements in the sample. Abelson and Sigmon (E501 describe a computational scheme for optimizing the depth resolution of RBS through modeling of noise sources. Elastic recoil detection (ERD) is complementary to RBS, and the two techniques are often used in combination. In ERD analysis, the beam strikes the sample at grazing incidence and the recoiling ions which escape the surface of the sample are detected. From the kinematics, stopping powers, and the recoil energy, the depth at which the collision occurred and the concentration of the recoiling species are deduced. When time-of-flight information is combined with the measured recoil energy, the mass determination of each recoil can be improved. In particular, ERD has good depth resolution for light elements in a heavy substrate. This technique is discussed in detail by Whitlow and co-workers (E51) and examples of RBS/ERD analyses are provided (E52-54). 3. Other Charged-Particle-InducedMethods. In addition to the aforementioned methods of analysis, energetic charged-particle beams have a number of other uses such as charged-particle emission analysis, resonant charged-particle reactions, and ion-induced microscopic mass spectrometry. These methods have been reviewed frequently (A21,A28,A41, A87, A105-113, A123) and applications are given in Table V. The use of the (d,p) and (d,a) reactions for the quantitative analysis of light elements on surfaces (E1151 and depth profiling with the 27Al(p,y)28Siand 19F(p,cuy)10 resonance reactions (E116) are typical of these studies. Computer programs which simulate the data obtained in these types of reactions have also been developed (E116). Schweikert and co-workers (A106, E l l 7-1 19) have used microbeams of heavy ions such as @Kr for particle-induced desorption mass spectrometry (PDMS) and the characterization of both organic and inor anic constituents of surfaces. Using very small numbers (

Nuclear and radiochemical analysis - Analytical ... - ACS Publications

Recommend Documents