Simultaneous pre-concentration procedure for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry

Abstract

In this paper is proposed a simultaneous pre-concentration procedure using cloud point extraction for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry. The ligand used is 2-(2-thiazolylazo)-p-cresol (TAC) and the micellar phase is obtained using non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The optimization step was performed using two-level factorial design and Doehlert design. A multiple response function was established in order to get experimental conditions for simultaneous extraction of cadmium and lead. The method allows the determination of cadmium and lead with detection limits of 0.077 μg L− 1 and 1.05 μg L− 1 respectively, precision expressed as relative standard deviation (RSD) of 1.5 and 3.3% (n = 10) for cadmium concentrations of 30 μg L− 1 and 50 μg L− 1, respectively, and RSD of 1.8% and 2.7% for lead concentrations of 30 μg L− 1 and 50 μg L− 1, respectively. The accuracy was confirmed by analysis of a certified reference material of natural water. This method was applied for the determination of cadmium and lead in drinking water samples collected in Jaguaquara City, Brazil. Tests of addition/recovery were also performed for some samples and results varied from 95 to 104% for cadmium and 96 to 107% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by Brazilian Health Organization.