| Speciation analysis recently becomes more attractive and has been developed quickly.It's not reliable to only determine total arsenic content in order to evaluate toxicity and bioavailability of arsenic.Generally speaking,inorganic arsenic is more toxic than organic arsenic,and arsenite is more toxic than arsenate.This work was performed to improve the method for determination of arsenic speciation in soil and sediment.The method was applied to geological survey,and more than 36 samples from Baotou city were detected using this method.The results can help to analyze arsenic content distribution,the space distributing,the condition and rule of transference and its influence on human health.The analysis of arsenic speciation in water,soil,plant and biological samples becomes a hot issue in environmental studies.In present experiment,studies on extraction of arsenic speciation (AsⅢ,AsⅤ,MMA and DMA) in soil and sediment and detection by IC-HG-AFS were carried out. Phosphoric acid was chosen as the extractant to investigate its effect on the release of arsenic from soils and sediment.The results show that:(1) The range analyses of orthogonale test with 3 factors and 3 levels(extraction times,extraction time,phosphoric acid concentration) showed that phosphoric acid concentration is the major factor effecting the extracting rate of arsenic speciation. Extraction efficiency of arsenic raised with the increase of phosphoric acid concentration.(2) Compared with ultrasonic wave the extraction of arsenic speciation in water bath achieved good result with 1.0mol·L-1 H3PO4 as an extractant.Extraction efficiency of arsenic is improved by 30%. (3) The addition of ascorbic acid in the phosphoric acid minimized the transformation between AsⅢand AsⅤ.(4) Inorganic arsenic was the major forms such as arsenate and arsenite,arsenate content was higher than the arsenite.The organic arsenic was not detected.(5) The recovery of standard addition was 71.92%～105.38%with precision of 2.61%～8.19%RSD(n=5).
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