Determination of arsenic, antimony, bismuth, germanium, tin, selenium and tellurium in 30% zinc sulfate solution by hydride generation inductively coupled plasma atomic emission spectrometry

Abstract

A method was developed for the determination of arsenic, antimony, bismuth, germanium, tin, selenium and tellurium at low ng g ^–1 levels in 30% m/v ZnSO ₄ , an important intermediate chemical in the manufacture of dry-cell batteries. Paradoxically, in order to achieve the detection limits required, it was necessary to dilute the zinc sulfate solution 10-fold. It was also necessary to match the zinc matrix in order to generate curves with similar sensitivities. Two separate determinations were necessary, one in high concentration acid (4.2 m), for selenium and tellurium, and the remaining elements in low concentration acid (0.1 m). The use of both l-cysteine (0.5% m/v) and l-histidine (0.65 m/v) was deemed necessary to provide the best conditions for the determination of arsenic, antimony, bismuth, germanium and tin. Method detection limits achievable, following 10 fold dilution, for the 30% m/v zinc sulfate matrix for As, Bi, Ge, Sb, Se, Sn and Te were 3, 3, 8, 2, 3, 2 and 38 µg l ^–1 , respectively. Precisions at concentrations of 25 µg l ^–1 for As, Bi, Sb, Se, Sn, were 2, 2, 2, 3 and 1%, respectively. The precisions for tellurium and germanium were poor: 30% for tellurium at a concentration of 100 µg l ^–1 and 30% for germanium at a concentration of 10 µg l ^–1 .