Determination of thallium traces from aqueous solutions using Iron(III) hexamethylenedithiocarbamate as a flotation collector and subsequent electrothermal atomic absorption spectrometry

Hexamethyleneammonium hexamethylenedithiocarbamate (HMA-HMDTC) was used as a new flotation reagent for enrichment and separation of thallium traces fr om aqueous solutions. HMA-HMDTC added to the first precipitate collector of hydrated iron(III) oxide (Fe2O3. xH(2)O) gives the second precipitate coll ector of iron(III) hexamethylenedithiocarbamate (Fe(HMDTC)(3)). During the coprecipitation step, thallium ions are incorporated in the structure of th e collector particles forming a sublate, which is separated from the proces sed water phase by flotation. After the preconcentration and separation ste p, a quantitative analysis is performed by electrothermal atomic absorption spectrometry (ETAAS). The diverse experimental parameters affecting the fl otation efficiency were determined and optimized. It was ascertained by a p roposed procedure that total thallium can be separated quantitatively by ad dition of 10 mg Fe-III and 3 mL 0.1 mol/L HMDTC- to the sample at pH = 6.0. The applicability of the proposed new procedure has been verified by the a nalysis of natural water samples by the method of standard additions and by inductively coupled plasma - atomic emission spectrometry (ICP-AES), as an independent comparative method. The limit of detection for thallium in thi s method is 0.024 mug/L.