Determination of bismuth and lead in geological samples by electrothermal AAS .1. Comparative study of tungsten containing chemical modifiers

A comparative study on the efficiency of some tungsten containing chemical modifiers such as W, W+Pd, W+Rh, W+Pt and W+Ru for thermal stabilization of Bi, In, Pb and Sb has been performed systematically by a Zeeman electrothermal atomization atomic absorption spectrometer (ETAAS). The addition of tartaric acid (TA) as a reducing agent additionally to the mixed modifiers was studied. A mixture of W+Pd+TA was found to be a powerful mixed modifier for the determination of Bi, In, Pb and Sb. Pretreatment temperatures could be increased up to 1250-1500 degrees C using this mixed modifier. The use of the mixed modifier results in an enhanced accuracy and precision of the method and recovery rates above 97% for all samples. The W+Pd+TA mixed modifier was applied to the determination of Bi and Pb in dissolved geological reference samples.