Cloud Point Extraction For Trace Metal In Environment Water Using Non-ion Surfactants

Flame atomic absorption spectrometry（FAAS） is one of the methods which are oftenused for determination of trace elements. However, when it is applied to analysis samplewith low concentration or complexed composition, preconcentration and separation areindispensable process to decrese and eliminate interfere from matrix. The conventionaltechnology can not meet the real requirements of trace elements, so novel separationmethod is must be proposed to optimize sensitivity,selectivity and determination limit.Cloud point extraction（CPE） has been widely used in the field of bioscience and envir-onmental sciences because of high extraction ratio and enrichment factor, simple operati-ion, no toxic volatilize solvent and connected with detectors. Recently, CPE has been ap-plied to enrich and separate metal elements even trace level companying with analyticalinstruments. This paper aimed at establish a new method for determinating trace metalelements in environmental water via CPE preconcentrating and separating trace metal ionsprior to detecting by FAAS to meet harsh requirements.This paper used non-ionic surfactants octylphenol ethoxylates （OP-8） and Triton X-100asextraction reagents, and employed1-（2-Pyridylazo）-2-Naphthol（PAN） complexed Co（Ⅱ）,dithzone complexed Pb（Ⅱ）, Cd（Ⅱ）, Ni（Ⅱ） detected by FAAS following.Experiment con-ditions such as, pH of solution, concentration of reagents affecting extraction ratio anddetect limit have been discussed in the two systems.OP-8--PAN system: In the optimal conditions, pH of solution8.5, CPE for Co（Ⅱ） withPAN, detect limit of FAAS is1.26ug·L^-1, RSD is2.5%. Recovery of real samples is96%-102%.Triton X-100system: In the conditions, pH of solution7.0, concentration of Triton X-1000.12%（v/v）, concentration of dithizon8×10^-5mol·L^-1, detect limit of Pb（Ⅱ）, Cd（Ⅱ）Ni （Ⅱ） are2.4ug·L^-1,3.2ug·L^-1,6.4ug·L^-1, RSD of Pb（Ⅱ）,Cd（Ⅱ）,Ni （Ⅱ） are2.6%,1.7%,3.4%. respectly. Recoveries of real samples are92%-105%.