CMU Intellectual Repository: Determination of cadmium and lead in Hhuman hair samples by cloud point extraction and atomic absorption spectrophotometry = การหาปริมาณแคดเมียมและตะกั่วในตัวอย่างผมมนุษย์โดยการสกัดแบบคลาวด์พอยต์และอะตอมมิกแอบซอปวันสเปกโทรโฟโตเมตรี / Sirikwan Suntithunyaroj

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Thesis Title Determination of Cadmium and Lead in Human Hair Samples by Cloud Point Extraction and Atomic Absorption Spectrophotometry

Author Miss Sirikwan Suntithunyaroj Degree Master of Science (Chemistry) Thesis Advisor Dr. Sukjit Kungwankunakorn

ABSTRACT

In recent years, human hair has been increasingly attracted the interest of researchers from the environmental and forensic science. Human hair has been used as an evident in suicide, poison and homicide police cases to prove whether the cause of death is from poison or not. Because the toxics of heavy metal can accumulate in hair for a long time. A simple and versatile methodology based on cloud point extraction (CPE) was applied as a preconcentration step for determination the amount of cadmium and lead in human hair samples and subsequent analysis by flame atomic absorption spectrophotometry (FAAS).

In experiment, the hair samples were decomposed by microwave-assisted digestion under suitable condition. For cloud point extraction, cadmium and lead were complexed with 1-(2-pyridylazo)-2-naphthol (PAN) to form hydrophobic complexes and using octylphenoxy-polyethoxyethanol (Triton X-114) as a surfactant. Then, the analyte was extracted into a small volume of the surfactant-rich phase after centrifugation and the mixture was cooled in order to increase the viscosity of

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surfactant-rich phase. The chemical parameters that affect the cloud point extraction, such as the concentration of surfactant and complexing reagent, complexing time, pH of the sample solution and the viscosity affecting the detection process were studied.

Under optimized condition, the cloud point was formed at 40ºC with complexing time of 30 minutes, a 5 ml of sample solution was used in the presence of 2×10^-4 mol l^-1 PAN and 0.04 %v/v Triton X-114 at pH 3. The method permitted the limits of detection of 0.03 and 0.61 Pg ml^-1 cadmium and lead, respectively. The proposed method has been applied to determine cadmium and lead in human hair samples using cloud point extraction and FAAS analysis.

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