Slurry-sampling Hydride Generation Atomic Spectrometry For Speciation Analysis Of Trace Arsenic

Determination and control of toxic trace elements in food are of importance for food safety and human health. The main purpose of this work was to establish a new atomic absorption spectrometric method combined with slurry sampling and hydride generation for speciation analysis of trace inorganic arsenic in food. A modifer reagent with both sensitizing and masking fuctions, optimal conditions of suspension and hydride generation were selected. A new method for direct determination and speciation analysis of inorganic arsenic is developed by using slurry sampling hydride generation atomic absorption spectrometry. This method has the characterastics of speediness, sensitivity and accuracy, and was successfully applied to speciation analysis of inorganic arsenic in food and health supplements.This paper includes three chapters:Chapter one:The advancement of slurry sampling method and speciation analysisThe advantages of slurry sampling are discussed. The advancement of speciation analysis of trace element is reviewed, and slurry sampling-hydride generation atomic spectrometry is expected. The basis and the innovation are clarified for this thesis.Chapter two:Direct determination of trace arsenic in flour by slurry sampling hydride generation atomic absorption spectrometry.A novel slurry sampling-hydride generation atomic absorption spectrometry was proposed for directly determination of trace arsenic in flour. The experimental conditions of suspension and hydride generation affecting the intensity of arsenic signal were investigated and optimized. The satisfactory result was obtained by using 0.3%(m/v) agar as a stabilizing reagent,1%(m/v) citric acid as a sensitizing reagent, and n-octanol as antifoam. The interferences of coexisting ions were examined. The reliability of the procedure was to be proved by analysing three kinds of Chinese certified reference flours, showing no significant difference (p=0.05) between the certified value and the value found by the proposed method. The method was applied to the determination of arsenic in flour samples with the detection limit of 0.239μg L-1, recovery of 97.8-101%, and relative standard deviation (n=3) of 0.86-3.02%. The proposed method has the advantages of simple operation, high speed and high sensitivity.Chapter three:Speciation analysis of trace inorganic arsenic in flours and dietary supplements by slurry sampling-hydride generation atomic absorption spectrometry.A new, rapid and sensitive atomic absorption spectrometric method is developed for speciation and determination of trace amounts of As(Ⅲ) and total inorganic arsenic (As) in flours and dietary supplements using slurry sampling hydride generation. The method is based on the leaching of arsenic from sample slurry through the sonication followed by hydride generation in the slurry and determination of the corresponding hydrides. The content of As(Ⅲ) was determined under 1% HCl acidity condition using both inhibitory effect of 8-Hydroxyquinoline (8-HQ) on As(Ⅴ) and its enhancing effect on As(Ⅲ). The content of total inorganic As was determined under 5% HCl acidity condition using enhancing effect of 8-HQ on both As(Ⅲ) and As(Ⅴ). The method detection limit was 4.0μg kg-1 for As(Ⅲ) and 4.5μg kg-1 for total inorganic arsenic. The recovery ranging from 93.3 to 107% were found for As(Ⅲ) and values from 91.3 to 108% for total inorganic As. The relative standard deviations (RSDs) were in the range of 2.3-4.7% and 1.0-3.8% for the determination of As(Ⅲ) and total inorganic As. respectively. This method was validated by means of the certified reference materials (wheat and rice flour), with good agreement with the certified values. The developed method was successfully applied to the speciation analysis of inorganic As in wheat flour, rice flour and dietary supplements with satisfactory results.