Thallium has been found to be an environmentally hazardous element because of its toxic effects on plants, mammals and humans [1, 2]. Due to the low concentrations of thallium in environmental, biological, clinical, geological and metallurgical samples, an analytical technique with high sensitivity and low detection limit is required [2, 3]. Therefore, graphite furnace atomic absorption spectrometry (GFAAS) coupled to electrochemical hydride generation (ECHG), as a sample introduction system, is an ideal candidate [4]. The choice of a suitable cathode material is of paramount importance in construction of ECHG electrolytic cell [3,4]. Usually, cathode materials with high hydrogen over-voltage are used for this purpose [3,4]. The present research utilizes a Lead-Tin alloy cathode material for ECHG of Thallium. The results indicate that the cathode material possesses a good sensitivity and low real samples such as natural waters. The effects of various experimental parameters, such as electrolysis time, electric current, carrier gas flow, catholyte type, catholyte concentration, modifier effect (for graphite furnace), temperature of atomizer, and solvent addition were studied and optimized. Under optimum operating conditions, the calibration plot was constructed which was linear in the range of 0.5-10 ng mL for thallium. The limit of detection (LOD) of the method was found to be 0.2 ng mL . Also, the relative standard deviation of the method was 3.5% (RSD, n = 5). Finally, the applicability of the method for determination of thallium in spiked tap water has been reported. 

Keywords