Speciation of Tl(III) and Tl(I) in hair samples by dispersive liquid-liquid microextraction based on solidification of floating organic droplet prior to flame atomic absorption spectrometry determination

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet was successfully used as a sample preparation method prior to flame atomic absorption determination of trace amounts of Tl(III) and Tl(I) in hair samples. In the proposed method, 1-(2-pyridylazo)-2-naphthol, 1-dodecanol and ethanol were used as chelating agent, extraction and dispersive solvent, respectively. Several factors that may be affected in the extraction process, such as type and volume of extraction and disperser solvents, pH, salting out effect, ionic strength and extraction time were studied. Under the optimal conditions, linearity was maintained between 6.0 and 900.0 ng mL−1 for Tl(III). The relative standard deviation for seven replicate determinations of 0.2 μg mL−1 Tl(III) was 2.5%. The detection limit based on 3Sb for Tl(III) in the original solution was 2.1 ng mL−1. The proposed method has been applied for the determination of trace amounts of thallium in hair samples and satisfactory results were obtained.