METHODS AND OBJECTS OF CHEMICAL ANALYSIS ISSN title: "Metody i obʺekty himičeskogo analiza" An international journal devoted to all aspects of Analytical chemistry ISSN 2413-6166 (Online), ISSN 1991-0290 (Print)
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Studing of selectivity of zinc and cobalt thiocyanate electrodes to thiocyanate ions in presence ClO₄⁻ and NO₃⁻

E.M. Rakhman’ko¹, Yu.V. Matveichuk², V.V. Yasinetski²

¹ Belarussian State University, str. Leningradskay, 14, 220030, Minsk, Belarus
² Mogilev State food-stuffs University, av. Shmidta, 3, 2120127, Mogilev, Belarus; е-mail: Yu_Matveychuk@mail.ru

The effect of background concentration ZnCl₂ and CoCl₂ on selectivity of Zn(NCS)₄^2--SE and Co(SCN)₄^2--SE based on trimethyl and trinonyloctadecylammonium QAS to SCN⁻ in the presence of interfering nitrate and  perchlorate ions have been studied. Introduction in solution ZnCl₂ and CoCl₂ fixes zinc and cobalt coming out of the membrane as a thiocyanate complexes, which have a high affinity for anion exchange QAS acidocomplexes compared with competing anions. Introduction in solution 3.5 mol/l CoCl₂ increases the selectivity to SCN⁻ on 4 orders, the introduction in solution 5.0 mol/l ZnCl₂ increases the selectivity for SCN⁻ on 5 orders for electrodes based on trimethyl QAS. It is shown that the electrodes based on trinonyloctadecylammonium QAS selectivity increases on 6 and 5 orders of Zn(NCS)₄^2--SE (5.0 mol/l background ZnCl₂) and Co(SCN)₄^2--SE (3.5 mol/l background CoCl₂).

Key words: potentiometry, selectivity, tetrathiocyanozincate and tetrathiocyanocobaltate-selective electrode

95-100