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ETAAS determination of thallium and silver from water matrix after colloidal precipitate flotation using lead(II) hexamethylenedithiocarbamate

Čundeva Katarina (St. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, Institute of Chemistry, Skopje, Macedonia)
Pavlovska Gorica (St. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, Institute of Chemistry, Skopje, Macedonia)
Stafilov Trajče (St. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, Institute of Chemistry, Skopje, Macedonia)

A fast method for the preconcentration of thallium and silver in nanogram quantities in fresh drinking waters (source, well, tap) and waters for irrigation using colloidal precipitate flotation is described. Lead(II) hexamethylenedithiocarbamate, Pb(HMDTC)2 played the role of flotation collector. The experimental conditions for the successful separation of thallium and silver (mass of Pb, amount of HMDTC-, pH of the system, induction time, type of surfactant etc.) were optimized. After flotation separation from the mother liquor, the solid sublate containing traces of thallium and silver was dissolved and the analytes were determined by electrothermal atomic absorption spectrometry (ETAAS). The results of the ETAAS analysis are compared with those obtained by inductively coupled plasma-atomic emission spectrometry. The detection limit for thallium by this method is 0.027 μg/l, and for silver 0.005 μg/l.

Keywords: thallium, silver, determination, water, colloidal precipitate flotation, ETAAS, lead(II) hexamethylenedithiocarbamate