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Direct Potentiometric Measurements of Cysteine by Using Iodide-Selective Electrode

Marija Bralić ; Department of Chemistry, Faculty of Technology, University of Split, 58000 Split, Croatia
Njegomir Radić ; Department of Chemistry, Faculty of Technology, University of Split, 58000 Split, Croatia

Sažetak

Potentiometric determination of cysteine (Cys) in aqueous solution by using iodide-selective electrode with (Ag2S + Agl) membrane is described.
The analytical behaviour of this electrode is discussed in terms of the potential vs. concentration curve, potential vs. pH curve, and potential-time response. The equilibrium potentials observed during serial dilution or standard addition, under constant pH and ionic strenght, are plotted against log c(Cys). The linear response with a slope 58 mV {p(Cys)}-1 has been obtained in the concentration range from 3 x 10-3 to under 10"5 M.
The change in potential in the tested concentration range of Cys (also designated as RSH) indicates RSAg coating formation at the exposed membrane surface. On the basis of potentiometric experiments, the solubility product of RSAg precipitate has been determined. The calculated mean value was pffsp(RSAg) = 18.66 ± 0.08.

Ključne riječi

Hrčak ID:

136776

URI

https://hrcak.srce.hr/136776

Datum izdavanja:

1.12.1994.

Posjeta: 527 *