Spectrophotometric Study of the Complex Formation of Anionic Chelates of Cobalt(II) with Monotetrazolium Cations

Abstract

The complex formation and extraction of anionic chelates of Co(II)–4-(2-thiazolylazo)resorcinol (TAR) with cations of monotetrazolium salts (TS) — (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and 3-(2-naphthyl)-2,5-diphenyl-2H-tetrazolium chloride (TV) — in the liquid–liquid extraction system Co(II)–TAR–TS–H2O–CHCl3 were studied by spectrophotometric methods. The optimum conditions for the extraction of Co(II) were found. The molar ratio of the components and the form of the anionic chelates of Сo(II) in the extracted compounds were determined by independent methods. The association process in the aqueous phase and the extraction process were investigated and quantitatively characterized. The following key constants were calculated: association constant, distribution constant, extraction constant, and recovery factor. The validity of the Beer’s law was checked, and some analytical characteristics were calculated. Based on the obtained results and the lower price of the monotetrazolium salt MTT compared with that of TV, the ion-associated complex of Co(II)–TAR–MTT can be implemented for determination of cobalt(II) traces in alloys and biological, medical, and pharmaceutical samples.