Simultaneous determination of arsenic, cadmium, copper, chromium, nickel, lead and thallium in total digested sediment samples and available fractions by electrothermal atomization atomic absorption spectroscopy (ET AAS)

Abstract

This study describes the optimization and validation of a quick and simple method for the simultaneous determination of total content and available fractions of As,Cr,Cu,Ni,Pb and Tl in sediments by ETAAS, which has been proved to be useful for environmental research. The optimization was carried out using a Box–Behnken factorial design which was applied to matrices of total digestion and to stages 1 and 2 of the modified BCR sequential extraction scheme for sediments in order to determine the appropriate atomization temperatures and masses for the chemical modifiers:P d(NO3)2 and Mg(NO3)2. The simultaneous determination of the elements in all matrices considered was performed,without the use of chemical modifiers at atomization temperatures of 1700 C for Cd and Tl,and 2100 C for As,Cu,Cr, Ni and Pb,using a standard calibration curve for calibration purposes. The characteristic masses and limits of detection obtained were 36.5,1.8,6.5,28,34,46.5 and 48 pg and0.11,0.001,0.022,0.04,0.2, 0.03 and0.003 mg ug- 1 for As,Cd,Cr,Cu,Ni,Pb and Tl,respectively. The analytical procedure was validated by analyzing three sediment certified reference materials(CRM NCSDC73315 and LKSD-4 for total contentand BCR701 for available fractions).Good accuracy was obtained(tested statistically, P=0.05, and shown by the high recovery for each element in each matrix),except for total As in the matrix of total digestion,where losses of the analyte could be attributed to sample treatment with HNO3. The precision of the procedure was between 0.6% and 6%.