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Study on Determination of Trace Copper, Cadmium , Zinc in Food Samples by Flae Atomic Absorption Spectrometry After Liquid-Liquid Extraction

Author: ZhouJie
Tutor: HanHuaYun
School: Zhengzhou University
Course: Analytical Chemistry
Keywords: Solvent extraction Cloud point extraction Atomic absorption spectrometry Food Copper Cadmium Zinc
CLC: TS207.51
Type: Master's thesis
Year: 2010
Downloads: 381
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Abstract

In recent years, due to the development of society and the improvement of living standards, the quality of the food requirements of the higher hope that the consumption of food is health, safety, and health. But in recent years, food by toxic heavy metals pollution is becoming worse, therefore, very important to accurately detect the content of heavy metals in food. Often need due to the generally low levels of heavy metals in food, chemical separation and enrichment means separation and enrichment of the analyte to improve the sensitivity and accuracy of the analytical method. The subject in the previous lot of work on the basis of solvent extraction, cloud point extraction and flame atomic absorption spectrometry combined with the determination of the new methods of food in copper, cadmium, and zinc. The research summarized as follows: (1) solvent extraction - flame atomic absorption spectrometry determination of trace amounts of copper in food research to the zinc reagent as a complexing agent to methyl isobutyl ketone the extractant solvent extraction - flame atomic Determination of copper in food absorption spectrometry. Study the various factors that affect the solvent extraction system to determine the best extraction conditions. In the solution, the copper may form a stable complex with the zinc reagent, generates a complex can be quantitatively extracted by methyl isobutyl ketone and enrichment enrichment after the organic phase can be directly by flame atomic absorption spectrometry. Optimal working conditions, the copper content in the law is obeyed in the range of 7.0 × 10-3 ~ 2.0μg · mL-1, the method detection limit of 6.7 × 10-3μg · mL-1 of 1.0μg · mL- a copper standard solution after this Law enrichment of 11 determinations, relative standard deviation (RSD) of 3.0%. The method used for food (soybean oil, cooking oil, rice, mung bean) Determination of Copper, with satisfactory results. (2) solvent extraction - flame atomic absorption spectrometric method for the determination of trace cadmium in food research diphenyl semicarbazide complexing agent (DPC), methyl isobutyl ketone extractant, cetyl trimethylammonium bromide ammonium (CTMAB) as a sensitizer, a solvent extraction - flame atomic absorption spectrometry determination of trace cadmium in food and water samples. Methods pH 9.0, 0.5 mL0.2% CTMAB 1.0 mL0.5% DPCs solution. Solution, 0.2 mL20% NaCl solution, 2.0 mL water saturated methyl isobutyl ketone, thoroughly shaken after extraction, the organic phase directly into sample, Flame atomic absorption spectrometry determination of cadmium in food and water samples. The best working conditions, the cadmium concentration of 2.0 × 10-3 ~ 0.24μg · mL-1 The linear range of a good relationship, the method detection limit of 1.5 × 10-3μg · mL-1, 0.2μg · mL- cadmium standard solution after this Law enrichment of 11 determinations, and the relative standard deviation was 1.0%, low detection limit, good reproducibility. The method used for the determination of cadmium in rice and water samples with satisfactory results. (3) The cloud point extraction - flame atomic absorption spectrometry determination of trace amounts of zinc in the food a cloud point extraction - flame atomic absorption spectrometry determination of trace amounts of zinc in the food new method. Methods 1 - (2 - pyridylazo) -2 - naphthol (PAN) as a chelating agent OP extractant, focuses on a variety of factors that affect the cloud point extraction, selected the best conditions, that pH 9.0, 1.0mL 2.0 × 10-3 mol L-1 PAN ethanol solution, 0.5 mL 10% OP solution, 1.0 mL20% NaCl solution and heated in a 90 ° C constant temperature water bath, 120 min. Optimal working conditions, the detection limit of the method was 3.4 × 10-3μg · mL-1, after this Law enrichment 0.5μg · mL-1 zinc standard solution of 11 determinations, relative standard deviation of 3.3. % enrichment factor of 20 times. The method used for the determination of zinc in rice, mung bean, wheat, corn, and satisfactory results.

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