Determination of Cd, Cu, and Pb after cloud point extraction using multielemental sequential determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS)

In the present paper a procedure for simultaneous preconcentration of Cd, Cu, and Pb using cloud point extraction (CPE) and multielemental sequential determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) is proposed. This preconcentration procedure is based on the metals extraction into micellar media of octylphenoxypolythoxyethanol (Triton X-114) after their reaction with 1-(2-pyridylazo)-2-naphtol (PAN). A Box-Behnken design was used to optimize the variables (pH, buffer concentration and volume of NaCl) involved in the extraction procedure. Enrichment factors were calculated as the ratio between the slopes of calibration equations with and without the preconcentration procedure in the TS-FF-AAS, with values of 59, 25, and 21 respectively for Cd, Cu, and Pb. Limits of detection (LOD) (3s(b), n = 10) were also calculated as 0.025, 0.38, and 0.43 mu g L-1 to Cd, Cu, and Pb, respectively. The precision (repeatability) expressed as relative standard deviation (RSD, n = 10) for reference standards of 10.0 and 20.0 mu g L-1 were 6.1 and 4.5% for Cd, 7.2 and 3.4% for Cu and 5.2 and 8.7% for Pb. The accuracy was confirmed through the analysis of certified reference material (NIST 1643d, Trace elements in water). The developed procedure was also applied to Cd, Cu, and Pb determinations in mineral water samples.