ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Coulometric Bromometric Titration of Free and Coordinately Linked Cyanides

J. Mocák, D. I. Bustin, and M. Žiaková

Department of Analytical Chemistry, Slovak Technical University, Bratislava 1

Abstract: The conditions of coulom9tric bromometric determination of cyanides in weak alkaline medium of the borate buffer solution are described. It is possible to titrate free cyanides and the cyanides linked coordinately in Cr(CN₆^3-)jp and Cr(CN)₆N03-. The equivalence point of titration is indicated biamperometrically. The presence of air oxygen influences the results of free cyanide determination. The reaction scheme is discussed on the basis of different results obtained in bromometric oxidation of cyanides and cyanide complexes. The determinations were performed in the concentration range from 94.8 to 2020 μg of KCN. The accuracy of determination corresponding to 95% probability is expressed for 2020, 776, and 94.8 μg of KCN by the reliability interval of i 10.1, ± 7.5, and ± 1.3 μg of KCN, respectively. The coulometric bromometric titration of cyanide is especially suitable for the determination of cyanides in the presence of chlorides and bromides. Chlorides do not interfere even if the ratio Сl^-/CN^- has the value of 2.7 X 104. Bromides do not interfere provided that the ratio Br^-/CN^- does not exceed the value of 5.9 X 10⁴.

Full paper in Portable Document Format: 262a126.pdf

Chemical Papers 26 (2) 126–132 (1972)