| Flame atomic absorption spectrometry is one of methods for analyse of trace elements in common use. Traditional preconcentration is not satisfactory when there are small-volumes samples and low content of trace metal elements. Separation/preconcentration procedures prior to trace element determinations have been explored to achieve more accurate, reliable and sensitive results and lower detection limits.Cloud point extraction (CPE) offers a conventional liquid-liquid extraction. CPE is based on the solubility and cloud point phenomenon of aqueous solutions of surfactants, upon alteration of the experimental conditions such as pH value of solution. The solution is separated into phases, which results in the separation of hydrophobe and hydrophile. CPE is an easy, safe, high efficiency and inexpensive methodology for preconcentration and separation. It has been used widely in the study of life sciences and environment sciences, and has also been successfully used in the preconcentration and separation of mental elements.The CPE method was based on employing Triton X-100 as nonionic surfactant, 8-Hydroxyquinoline (8-HQ) and l-(2-Pyridylazo)-2-Naphthol (PAN) as complexing reagent. The optimum conditions are 0.10mL 0.10mol/L 8-HQ, 0.50mL 30%Triton X-100, heated in a thermostated bath at 100℃ for 20 min.Under the optimum conditions, the limit of detection of 9.55ng/mL for nickel(pH 5.0), 2.23ng/mL for cadmium(pH 4.5), 0.0432 μg/mL for lead(pH 3.0), 0.0694 μg/mL for copper(pH 8.0) respectively. The optimum conditions are 0.20mL 8×10-3 mol/L PAN, 0.50mL30% Triton X-100, heated in a thermostated bath at 100℃ for 25 min with PAN as chelating reagent.Under the optimum conditions, the limit of detection of 0.0141 μg/mL for nickel, 0.0528 μg/mL for lead without adding any buffering reagent. The standard addition recovery of element approximates 100%. The proposed method was applied to the determination in real samples and the results are satisfying.
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