INVESTIGATIONS FOR THE DETERMINATION OF LEAD BY IN-SITU HYDRIDE TRAPPING WITHIN A GRAPHITE ELECTROTHERMAL ATOMIZER FOR ROUTINE ANALYSIS

A new commercial system consisting of a how injection analysis system for hydride generation coupled with a transversely heated graphite atomizer-atomic absorption spectrometer for the determination of lead is investigated in detail. The hydride generation is optimized by using an ammonium peroxodisulphate-hydrochloric acid system as oxidant and sodium borohydride as reducing reagent. The addition of sodium cumol sulphonate as surface active substance shows advantages considering efficient plumbane production. The hydride trapping and atomization in a graphite electrothermal atomizer is also optimized. The characteristic concentration was 0.74 mu g/l, the detection limit was 0.70 mu g/l for 500 mu l sample volumes. The relative operation standard deviation of this method was smaller than 2%. Further examinations demonstrate the influence of several heavy metals on the determination of lead. Finally, the measurement of standard reference materials shows the efficiency of the method in combination with decomposition with aqua regia solutions.