Simultaneous cloud point extraction and determination of ZN, CO, NI, and PB by flame atomic absorption spectrometry

Abstract

A simple cloud point extraction method has been proposed for the preconcentration and simultaneous determination of Zn(II), Co(II), Ni(II) and Pb(II). The pH of sample solution was adjusted to 8.5 with buffer and the cations complexes with 2-guanidino benzimidazole. Triton X-114 was added as a non-ionic surfactant. After the phase separation at 65 ± 1°C the surfactant - rich phase was diluted to 1.5 ml using ethanolic solution of HN03 and the analytes were determined by flame atomic absorption spectrometry. The influence of variables upon the complexation and extraction such as pH, ligand concentration surfactant concentration etc. was studied. Preconcentration of 50 ml sample solution in presence of Triton X- 114 (0.05% v/v) provided detection limits of 8.8, 4.9, 7.8 and 11 ng mL-1 for Zn, Ni, Co and Pb, respectively. Dynamic linear range of concentration, relative standard deviation and the enhancement factors are as follows: 8.8-80,4.9-3000, 7.8-2000, 11-6000 ngmL-1; 5.2%, 4.3%, 7.8%, 3.2%; 13, 15.5, 15, 29.6 for Zn, Ni, Co and Pb respectively.