LITERATURE CITED
(1) Amador, E., Wacker, W. E. C., Clin. Chem. 8, No. 4, 343 (1962).
(2) Blaedel, W. J., Hicks, G. P., ANAL. CHEM.34, 388 (1962). (3) Cammarata, P. S., Cohen, P. P., J. Biol. Chem. 187, 439 (1950). (4) Hicks, G. P., Ndevac, G. N., unpublished data, Department of Medicine, University of Wisconsin, 1964.
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(1955). (8) Sigma Chemical Company, St. Louis, Mo., Tech. Bull. No. 505, 1958. (9) Struck, J. J., Sizer, I. W., Arch. Biochem. Biophys. 86, 260 (1960).
(10) Wilkinson, J. H., "An Introduction to Diagnostic Enzymology,' ' Williams and Wilkins, Baltimore, 1962. RECEIVEDfor review October 19, 1964. Accepted December 31, 1964. Work supported by grants No. AT (11-1)-1082 from Atomic Energy Commission, KO. IN-35-D from the American Cancer Society, and No. G-72-3 from National Institutes of Health, United States Public Health Service.
Preconcentration of Trace Elements by Precipitation Ion Exchange FOUAD TERA, R. R. RUCH, and G. H. MORRISON Department of Chemistry, Cornell University, Ithaca, N .
b A new approach to preconcentration of trace elements, precipitation ion exchange, is demonstrated whereby matrix and traces are sorbed on a cation exchange column, the matrix is precipitated by concentrated HCI, and traces are then eluted with additional HCI. The separation is based on the insolubility of the matrix and the low selectivity of the traces in 12.2M HCI. Many trace elements were found to be concentrated in greater than 90% yields, matrix-free or with only small amounts of matrix from NaCI, KCI, BaCl2, SrCI2, and AgCI.
Y.
plicability of the approach is governed by .two main conditions. First, the matrix must be insoluble or only sparingly soluble in the eluent to prevent early breakthrough, and, second, the trace elements must have a very low distribution coefficient (preferably D,
