PRECONCENTRATION BY COPRECIPITATION OF LEAD AND SELENIUM WITH NI PYRROLIDINE DITHIOCARBAMATE COMPLEX AND THEIR SIMULTANEOUS DETERMINATION BY INTERNAL STANDARD ATOMIC-ABSORPTION SPECTROMETRY WITH THE SOLID SAMPLING TECHNIQUE

In order to determine concentrations below mu-g/kg level of Pb and Se in water samples, the direct simultaneous determination of solid samples by graphite furnace-AAS using a miniature cup technique is applied to coprecipitation samples obtained by using a combination of ammonium pyrrolidine dithiocarbamate (APDC) and Ni as a carrier element. In the present work, the internal standard method was employed for AAS determination. In case of using the internal standard method weighing was not necessary. Examinations on the coprecipitation of Pb and Se with the Ni-APDC complex have been carried out. Detection limits for Pb (II) and Se (IV) are 30 ng and 70 ng/L, respectively, based on 100-mL sample volume. Precision (relative standard deviation of 10 determinations) of the determination of Pb and Se at concentration of 0.05-mu-g/L was 6.9 and 4.5%, respectively.