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Anal. Chem. 1982, 5 4 , 1048-1052
Of these three factors, the first is the most significant. Since the entrance slit is common to all 16 elements, asymmetric slit settings, unequal slit widths and/or heights, would be necessary. However, asymmetric slit settings provide rather complex compromises for the signal-to-nosie ratios. This is shown in Table I11 where the signal-to-noise ratios were determined for Mn (279.5 nm) for all the possible entrance and exit slit width combinations at a constant slit height. The slit height matrix at a constant slit width was similar. I t is apparent that the determination of the optimum compromise slit parameters for each element is a formidable task. The gain in the signal-to-noise ratios does not justify the cost, time, and effort required to change the existing exit slits. With the purchase of a new multielement cassette, larger exit slit parameters would allow improved signal-to-noise ratios. Data for more elements are necessary, however, before the optimum compromise asymmetric entrance and exit slits can be selected.
LITERATURE CITED (1) Snellernan, W. Specfrochim . Acta, Part B 1968, 2338, 403. (2) Nltls, G. J.; Svoboda, V.; Wlnefordner, J. D. Spectrochim. Acta, Part B 1972, 2 7 8 , 345. (3) Velllon, C.; Merchant, P. Appl. Spectrosc. 1973, 2 7 , 361. (4) Kellher, P. N.; Wohlers, C. C. Anal. Chem. 1974, 4 6 , 682.
(5) Keliher, P. N.; Wohlers, C. C. Anal. Chem. 1976, 48, 140. (6) Zander, A. T.; O'Haver, T. C.: Kellher, P. N. Anal. Chem. 1978, 4 8 , 1166. (7) Harnly, J. M.; O'Haver, T. C.; Golden, 9.;Wolf, W. R. Anal. Chem. 1979, 5 1 , 2007. (8) O'Haver, T. C.; Harnly, J. M.; Zander, A. T. Anal. Chem. 1977, 4 9 , 666. (9) Harnly, J. M.; O'Haver, T. C. Anal. Chem. 1981, 5 3 , 1291. (IO) Dealan, L.; Winefordner, J. D. Spectrochim. Acta, Part B 1968, 2 3 8 , 277. (11) Harnly, J. M. Mlller-Ihll, N. J.; O'Haver, T. C. J . Autom. Chem., in Dress. (12) barsons, M. L.; McCarthy, W. J.; Wlnefordner, J. D. Appl. Spectrosc. 1968. 20. 223. (13) O'Haver, T. C. "Trace Analysis: Spectroscopic Methods for Elements"; Wlnefordner, J. D., Ed.; Wiley: New York, 1976;Chapter 2.
RECEIVED for review November 19, 1981. Accepted March 8, 1982. Presented in part at the 7th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies, Philadelphia, PA, 1980, and the 32nd Pittburgh Conference, Atlantic City, NJ, 1981. Mention of trademark or proprietary products do not constitute a guarantee or warranty of the product by the US. Department of Agriculture and does not imply their approval to the exclusion of other products that may also be suitable.
Hydride GenerationKondensation System with an Inductively Coupled Argon Plasma Polychromator for Determination of Arsenic, Bismuth, Germanium, Antimony, Selenium, and Tin in Foods M. H. Hahn,' K. A. Wolnik," and Fred L. Fricke Elemental Analysis Research Center, USFDA, 114 1 Central Parkway, Cincinnati, Ohio 45202
J. A. Caruso Depatfment of Chemistry, University of Cincinnati, Cincinnati, Ohio 4522 1
A hydride generation/condensation system is interfaced to an inductively coupled argon plasma poiychromator for the simultaneous determinatlon of As, Bi, Ge, Sb, Se, and Sn in foods. Detection llmlts range from 0.02 ng/mL for As to 0.80 ng/mL for Sn, and preclsion values at 10 ng/mL are less than 6% relatlve standard devlatlon. Results of analyses of NBS standard reference materlals (wheat flour, rlce flour, spinach, and orchard leaves) demonstrate the appllcation of the method to food matrices.
The analytical potential of the inductively coupled argon plasma (ICAP) polychromator for the analysis of many trace elements in food products is unmatched in terms of speed, cost, and relative simplicity. However, several elements that are of current interest to scientists in food-related disciplines are often present at concentrations that are near or below the direct quantitative capabilities of the ICAP. 'Present address: B e l l Laboratories, 2525 Shadeland Ave., anapolis, IN.
Indi-
Because of the nutritional and/or toxicological significance of elements such as arsenic, antimony, bismuth, germanium, selenium, and tin, accurate and precise quantification is required for proper assessment of their metabolic roles. A combination of factors, most significantly the poor sensitivity of the ICAP polychromator for the emission lines of these elements, necessitates the use of one or more preconcentration steps prior to their determination by ICAP ( 1 ) . The formation of volatile hydrides with this group of elements has been frequently used to improve sensitivity and detection limits for spectrometric determinations and is well documented in the literature (2). Coupling of the hydride generation reaction to an ICAP system, on the other hand, is fairly recent. In 1978, Thompson et al. ( 3 ) introduced a continuous hydride generation/ICAP system for the simultaneous determination of As, Bi, Sb, Se, and Te. Since that time, several modifications of their basic design have appeared in the literature ( 4 , 5 ) . These continuous generation systems provide improved detection limits by at least an order of magnitude over conventional nebulization and include studies on the plasma determination of hydrides of Ge and Sn (6) and P b (5). Wolnik et al. (7) expanded the technique with the
Thls article not subJect to U.S. Copyrlght. Published 1982 by the American Chernlcal Society
ANALYTICAL CHEMISTRY, VOL. 54, NO. 7, JUNE 1982
Table 11. Operating Parameters
Table I. Analytical Wavelengths element As
Bl Ge Sb
Se Sn
wavelength, bkgd nm correctiona order 193.70 223.06 199.82 217.58 196.03 189.98
1049
t f
-
1
2
1 1 1
2
i - , background
ICAP Polychromator forward power, kW 0.9
