An efficient, simple and sensitive ligand less, ion pair based dispersive liquid liquid microextraction technique was used for preconcentration and determination of trace levels of total thallium followed by electrothermal atomic absorption spectrometry. In this method, thallium (III) was complexed by bromide ion to produce negative charged thallium bromide complex followed by addition of cetylpyridinium chloride as a counter ion to form hydrophobic complex which was extracted into the extraction solvent by dispersive liquid liquid microextraction. In this method, a mixture of 1.5 mL of methanol (as disperser solvent) containing 150 µL of chloroform (as extraction solvent) was injected as extractant. Under the optimum conditions, the calibration curve was linear in the range of 0.1 − 2 µ g L−1 of thallium (III) with a correlation coefficient of 0.9983. The limit of detection was 0.03 µ g L−1 and the relative standard deviation based on six replicate analysis of 1 µ g L−1 thallium (III) was 4.1%. The accuracy of the method was checked by the analysis of certified reference material and spike methods. The method was applied for determination of trace levels of thallium in water and spinach samples.

Keywords