Determination of thallium in water samples via solid sampling HR-CS GF AAS after preconcentration on chromatographic paper

Abstract

A method for determining thallium in water samples via solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry (SS HR-CS GF AAS) after preconcentration using chromatographic filter paper as a solid support was proposed. The effects of pH, stirring time, and sample volume in the analyte preconcentration step were studied. The presence of potential interferences in the sample and the type of masking agent were also examined. In the proposed procedure, the sample was placed in contact with the solid phase in a polypropylene tube, and after stirring for 3 min, thallium determination was performed via HR-CS GF AAS directly on chromatographic filter paper. A preconcentration factor of 55, a precision of 9.4% (n = 10; 10 μg L−1), a limit of detection of 0.018 μg L−1, and a limit of quantification of 0.059 μg L−1 were achieved. Analyte addition and recovery tests were performed, and the results ranged from 91% to 110%. The accuracy of the method was evaluated by analyzing a water reference material. The procedure was used to determine thallium in water samples collected in Barreiras, Bahia, Brazil. The results were compared with those obtained using inductively coupled plasma‒mass spectrometry (ICP‒MS). Thallium concentrations in the analyzed samples ranged from <0.059 to 0.80 μg L−1.