Anal. Chem. 1991, 63,33R-40R
Geological and Inorganic Materials L. L. Jackson,**1T.L. Fries? J. N.Grossman,s B.-S. W.King? and P. J. Lamothe*
U.S. Geological Survey, P.O. Box 25046,Denver Federal Center, MS 973,Denver, Colorado 80225,U S . Geological Survey, 345 Middlefield Road, MS 938,Menlo Park, California 94025,and U.S.Geological Survey, National Center, M S 923,Reston, Virginia 22092
INTRODUCTION This review s w e y s the literature for the 2-year period since our previous review (AI),Nov 1988 through Oct 1990. In order to prepare this review, we performed a computerized keyword search of Chemical Abstracts and manually searched several of the primary journals. Our literature search identified more than 2600 pertinent references. A similar number was obtained for each of our two previous reviews, and once again we have cited about 400 of those references. In many instances, foreign language articles have been reviewed solely from the abstract. We have followed a similar format as in our revious reviews, although our contributing author list has cianged. We have continued to focus on and highlight current trends in geochemical analysis. Our primary emphasis has been to cite a plications of the determmation of inor anic species in geO ~ O‘cal materials that offer significant ctanges to research anfroutine work. For many of the topics covered, the references are simply too numerous to cite and only representative examples are included. During this review period, every conceivable technique for separation and determination of gold and platinum group elements (PGE) seems to be appemng. Renewed interest has surfaced in understanding and developing fire-assay techniques. New instrumental techniques such as inductively coupled plasma mass spectrometry (ICPMS) are more commonplace and almost de rigueur for the determination of rare earth elements (REE). Through the use of laser ablation and microbeam techniques, many geological studies have focused on microanal sis of individual mineral grains. Specific as studying Cretaceous-Tertiary boundar problems, samples for elemental anomalies, have also received consii erable attention. In addition, a resur ence has occurred in environmentally oriented geochemicaf studies aimed at understanding processes, particularly in sedimentr,.
SUCK
GEOSTANDARDS Geostandards Newsletter has continued as the major forum for articles related to eological reference materials and compilations of analyticaf data. In 1989, a special issue of the journal was dedicated to the compilation of working values for 272 geoatandards (BI). Another special issue lists almost loo00 results from 1400 references for a single standard-U.S. Geological Survey basalt BCR-1 (B2). Unfortunately the standard is no longer available, but the number of citations attests to the importance of well-characterized international eological reference materials. Other data com ilations have %,en published for six French rock samples (l!3), four CanChinese rock adian soils (B4)and three Canadian rocks (IS), and stream sediment samples (B6),and the Japanese igneous rock series including elemental data (B7)and isotopic ratios (B8). Terashima et al. (B9)described the preparation of the Geological Survey of Japan’s sedimentary rock series and reported the elemental content of the suite of nine rocks and sediments. The Geological Survey of Canada’s eight lake and the USGS Devonian shale stream sediment samples (BlO), SDO-1 ( B I I ) ,and the National Institute of Standards and (NIST) new river sediment SRM 2704 (B12)have been simi arly described. NIST has also released a new suite of cement reference materials and, for geochronologists, a
TechnOIT
*Author to whom correspondence should be sent. U.S.Geological Survey, Denver. *US.Geological Survey, Menlo Park. U S . Geological Survey, Reston.
ber llium standard-SRM 4325. deostandards Newsletter has continued its annual bibliography on geochemical reference samples (B13,B14). Roelandts also cataloged over 170 eochemical standards and provided references to compilef data (B15). S A M P L E PREPARATION A N D DISSOLUTION The sample preparation step is frequently the most time consuming and a ma’or potential source of error in any geochemical analysis. dumerous approaches have been used to automate this step such as using robots to ind samples (C1) or to perform acid digestions. The use o microwave ovens to speed up the digestion process is becoming common lace. In the last 2 years, numerous articles have appearex that focused on using microwave ovens for digesting specific sample types such as rocks, sediments, sewage sludges, and biological matrices (e.g., C2). Microwave and conventional methods for drying soils have been examined in relation to changes in extractability of nutrients (C3).Drying-induced losses of S and chan es in S isotopic ratios in sediments have also been studied ( E d ) . In general, there seems to be a focus on dissolution procedures. This is epitomized by the book by Sulcek and Povondra, Methods of Decom osition in Inorganic Analysis (C5),an update of the book tLt they co-authored with Dolzal in 1966. The text includes sections on wet decompositions, fusion, sintering, and decomposition at high temperature and with reactive gases. There are extensive references to the decomposition of s ecific minerals and rock types including a fairly extensive %iscussion of the various fire-assay techniques and associated problems. Others have reported on decomposition procedures for specific matrices such as chromites and ferrochrome slags (C6),sulfate minerals (e.g., native sulfur (C8),and cinnabar (C9).Sholkovitz barite) (0, (CIO)compared HF dissolution and lithium metaborate fusions of marine sediments and pointed out how the decomposition methods commonly used for REE determinations have influenced the interpretation of river inputs and oceanic abundances of REE. Additional research on sediment decomposition has involved pressure leaching of B as a paleoan interlaboratory study of the US. salinity indicator (C11), Environmental Protection Agency’s (EPA) SW-846, Method 3050, acid digestion of sediments, sludges, and soils (C12)and proposed modifications of the EPA method to improve recovery of Ag and Sb (C13).In the interlaboratory study of EPA Method 3050,23 elements were determined b atomic abso tion techniques. The mean relative standard ieviation (RS8for all elements for all laboratories was 9.4%, whereas for individual laboratories it was 5.4%. Other work on digestion modifications has included the addition of lithium sulfate to lithium metaborate to speed up the conventional the study of closed lithium metaborate fusion of silicates (C14), vessel digestion of soils to prevent volatilization of Se and As (C15),and the comparison of acid digestion and alkali fusion for the ICPMS determination of heavier elements such as Y, Zr,Hf, Nb, and REE (C16). The su pression of B volatilization during acid digestion (HF and fICl) has been achieved using mannitol at greater than 1:l mole ratio of mannitol/ boron (C17).There was no isotopic fractionation, even for small amounts of B (
