Preconcentration procedure using cloud point extraction in the presence of electrolyte for cadmium determination by flame atomic absorption spectrometry

摘要

This paper describes a micelle-mediated phase separation in the presence of electrolyte as a preconcentration method for cadmium determination by flame atomic absorption spectrometry (FAAS).Cadmium was complexed with ammonium O,O-diethyldithiophosphate (DDTP) in an acidic medium (0.32 mol 1~(-1) HC1) using Triton X-l 14 as surfactant and quantitatively extracted into a small volume (about 20 mul) of the surfactant-rich phase after centrifugation.The chemical variables that affect the cloud point extraction,such as complexing time (0-20 min),Triton XI14 concentration (0.043-0.87% w/v) and complexing agent concentration (0.01-0.1 mol l~(-1)),were investigated.The cloud point is formed in the presence of NaCl at room temperature (25 deg C),and the electrolyte concentration (0.5-5% w/v) was also investigated.Under optimized conditions,only 8 ml of sample was used in the presence of 0.043% w/v Triton X-l 14 and 1% (w/v) NaCl.This method permitted limits of detection and quantification of 0.9 mug 1~(-1) and 2.9 mug l~(-1) Cd,respectively,and a linear calibration range from 3 to 400 mug 1~(-1) Cd.The proposed method was applied to Cd determination in physiological solutions (containing 0.9% (w/v) of NaCl),mineral water,lake water and cigarette samples (tobacco).