Anal. Chem. 1980, 52, 1708-1710
1708
total salt concentration of the measured sample exceeded 1.5 M. Applications. The purity of silicon tetrachloride, a starting reagent for the production of epitaxial silicon films and optical waveguide materials, must be assured with respect t o transition metal impurities. Iron has been previously identified as usually the only detectable, soluble transition metal impurity present in the prefiltered material (24). Since high purity silicon tetrachloride may contain sub-nanogram amounts of this impurity, analysis by laser intracavity spectrophotometry was performed as a real world application. Four aliquots of a purified sample were added to precleaned 100-mL Teflon beakers and evaporated to dryness on a ceramic top hot plate located inside a laminar flow hood located in a clean room. Samples were vaporized within 5 min. Four empty beakers were placed along with beakers containing samples and processed identically as blanks. After evaporations of SiCl4, during which iron traces are retained without loss (24),residues were dissolved in 0.5 mL of concentrated H F and t h e resulting solution was evaporated to dryness. After t h e addition of 5.0 m L of 1.1M HC1 purified by subboiling distillation, samples were heated briefly and then processed as described in the Experimental section. Quadruplicate determinations yielded blank values of 0.5 & 0.1 ng and iron was found a t the 2.3 i 0.2 ppb level in silicon tetrachloride.
LITERATURE CITED (1) Peterson, N. C.; Kurylo, M. J.; Braun, W.; Bass, A M.; Keller, R. A. J . Opt. SOC A m . 1971, 6 1 , 746-750.
Thrash, R. J.; Weyssenhoff. H.: Shirk, J. S. J , Chem. Phvs. 1971, 55, 4659-4660 Klein, M B Opt Commun 1972, 5 , 114-116 Childs, W J Fred, M S I Goodman, L S Appl Opt 1974 73 2297-2299 Hansch, T. W.; Schawiow, A. L.; Toschek, P. E. I€€€ J . Quantum Nectron. 1972, 8 , 802-804. Keller, R . A.; Simmons, J. D.; Jennings. D. A. J . Opt. SOC.Am. 1973, 63, 1552-1555. Atkinson, G. H.; Laufer, A. H.; Kurylo, M. J. J . Chem. Phys. 1973, 5 9 , 350-354. Chackerion, C., Jr.; Weisbach, M. F. J . Opt. SOC. A m . 1973, 63, 342-345. Keller, R . A.; Zalewski, E. F; Peterson, N. C. J , Opt. SOC.Am. 1972, 62, 319-326. Spiker, R. C., Jr.; Shirk, J. S. Anal. Chem. 1974, 4 6 , 572-574. Horiick, G.; Codding, E. G. Anal. Chem. 1974, 4 6 , 133-136. Konjevic, R.; Konjevic, N. Spectrosc. Leff. 1973, 6. 177-181. Green, R. B.; Latz, H. W. Specfrosc. Lett. 1974, 7 , 419-430. Maeda, M.; Ishitsuka, F.; Miyazoe, Y. Opt. Commun. 1975, 73, 314-317. Maeda. M.; Ishitsuka, F.; Matsumoto, M.; Miyazoe, Y . Appl. Opt. 1977, 16, 403-406. Atkinson, G. H.; Heimlich, T. N.; Schuyler, M. W. J . Chem. Phys. 1977, 66, 5005-5012. Fishman, M. J.; Erdmann, D. E. Anal. Chem. 1979, 51, 317R-341R. Kundra, S. K.; Katyal, M.; Singh, R . P. Anal. Chem. 1974. 4 6 , 1605- 1606. Gibbs. C. R . Anal. Chern. 1976, 48, 1197-1201. Shirk, J. S.; Harris, T. D.; Mitchell, J. W. Anal. Chem., preceding paper in this issue Mitchell, J. W.; Harris, T. D.; Blitzer, L. D. Anal. Chem. 1980, 52, 774-776. Mitchell, J. W. Anal. Chem. 1978, 5 0 , 194-196. Zief, M.; Mitchell, J. W. "Contamination Control in Trace Element Analysis"; Wiley-Interscience: New York, 1975; pp 104-106. Kometani, T. Y. Anal. Chem. 1977, 49, 2289-2291.
RECEIVED for review January 25, 1980. Accepted June 9, 1980.
Simultaneous Determination of Zirconium and Hafnium in Solutions by X-ray Fluorescence Spectrometry Enzo Ricci" Analytical Chemistry Division, Oak Ridge National Laboratory, P.O.
Box X, Oak Ridge, Tennessee 37830
The importance of Zr and Hf in nuclear reactor research and development is well established. A reliable X-ray fluorescence method (XRF) was developed to determine these two elements simuttaneously in (0.5-1.0 M H2S04)solutions at levels ranging from 0.5 to 200 ppm. Handling of serial samples is enabled by a 90-sample changer and by the simple chemistry involved. Ferric hydroxide is precipitated with ammonia in a test tube. After washing, the Fe(OH), slurry Containing all the Zr( OH), and Hf(OH), is transferred to a 6.4 pm thick Mylar mount where it is quickly dried on a steam bath. These mounts are inexpensive, hold well during drying, and provide a
