Amperometric determination of bismuth (III) using mercaptoethylamino-N,N,S-triacetic acid

The authors use a sulfur-containing complexone, mercaptoethylaminoN,N,N-triacetic acid (MEATA), for the determination of Bi(III) by the method of amperometric titration. The complex-forming properties of MEATA with 12 cations in the range of pH 2.5-12.0 were investigated and the dissociation constants of MEATA were determined by the method of potentiometric titration. A voltametric study of MEATA was conducted using the LP-9 electronic polarograph. As a result of an investigation of the process of complex formation by the method of amperometric titration it was established that bismuth (III) reacts with the complexone to form a colorless soluble compound in ammonia-acetate buffer mixtures with pH 3.3-6.0, as well as in a supporting electrolyte of 0.1 M H/sub 2/SO/sub 4/. The method of amperometric titration of bismuth using MEATA was applied to the analysis of a thermoelectric semiconductor material with composition, %: 20.3 Bi; 57.5 Te; 24.6 Sb; 3.5 Se, which is used in refrigerating devices and generators for the direct transformation of thermal to electric energy. Also studied was the possibility of selective determination of bismuth. It was established that substantial amounts of Ag, Al, Cd, Zn, Co, Ca, Ni, Cr, Ti, Mg, Pb, As, V, Se, Te, 70-fold excesses of Mo (VI),more » 50-fold excesses of Hg (II) and small quantities of Cu (II), Mn (II), and Sb (III) do not interfere.« less