Model experiments for determinations of zinc—amino acid complexes in biological fluids by polarography

The Ilkovi? constant was determined for zinc and zinc—amino acid complexes by using differential pulse polarography in 0.1 M sodium chloride—sodium diethylbarbiturate buffer at pH 7.4. A single well-behaved wave was obtained, except for cysteine and cystine for which useful calibration curves could not be obtained. The non-equilibrium dialysis of the amino acid complexes was studied in a hollow-fiber dialyzer. It is concluded that the dialysis step could be used in a method intended to measure available zinc but that the polarographic method needs further modification.