Flame atomic absorption spectrometric determination of trace amounts of thallium in natural waters and standard pepperbush after solid-phase extraction on to amberlite XAD-2 resin modified with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

A procedure for separation and preconcentration of trace amounts of thallium has been proposed. It is based on the adsorption of thallium(l) ions solution on to a column of Amberlite XAD-2 resin loaded with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. Thallium is quantitatively retained on the column in the pH range of 8.5-12.0 at a flow rate of 15 mL min(-1). The retained analyte on the resin recovered with 5.0 mL of 4% ascorbic acid and thallium is determined by flame atomic absorption spectrometry. In this case, 0.18 mu g of thallium can be concentrated in the column from 1200 mL of aqueous sample, where its concentration is as low as 0.15 ppb. Eight replicate determinations of 2.0 ppm of thallium gave a mean absorbance of 0.044 in final ascorbic acid solution with a relative standard deviation of +/- 1.68%. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of thallium in natural waters and various standard samples.