The choice of a suitable cathode material is of paramount importance in construction of ECHG electrolytic cell. Usually, cathode materials with high hydrogen over-voltage are used for this purpose1. In the present research, new cathodic materials based on tungsten alloys are introduced to be used in electrochemical hydride generation (ECHG) coupled to graphite furnace atomic absorption spectrometry (GFAAS) for determination of thallium in tap water. In comparison to other cathodic materials used to date for electrochemical hydride generation of thallium, performance of the tungsten alloys cathodes is substantially better in the following aspects: higher interference tolerance, higher corrosion resistance and longer useful working time. Experimental design as a powerful, practical and useful tool can use for screening and optimization of effective factor in analytical methods2. Here, the Plackett–Burman design was applied for screening of effective variables on electrochemical hydride generation of Thallium. Electrolysis time, electric current, carrier gas flow, catholyte concentration, temperature of atomizer were proved to be significant factors. These parameters were optimized by using a Box–Behnken design and the response surface equations were derived. Under optimum conditions, the calibration plot was constructed which was linear in the range of 0.05-0.3 ng mL−1 for thallium. The limit of detection (LOD) of the method was found to be 0.014 ng mL−1. Also, the relative standard deviation of the method was 1.8% (RSD, n = 7). Finally, the applicability of the method for determination of thallium in spiked tap water has been reported.

Keywords