Determination of Arsenate and Arsenite in Drinking Water and Bottom Mud by Ion Chromatography

Ion chromatography was applied to the determination of arsenate (AsO3-4) and arsenite (AsO3-3) in environmental samples.Ion Pac AS4-SC was chosen as the analytical column,and a mixed solution containing 1.8 mmol·L-1 Na2CO3 and 1.6 mmol·L-1 NaHCO3 was used as the eluant.Suppressed conductivity detection was applied in the determination.Linear relationship between the peak area (or peak height) and the concentration of AsO3-4 (or AsO3-3) was kept in the range of 0.09-35 mg·L-1 (correlation coefficient,r=0.999 8).Detection limits (3S) were found to be 2 μg·L-1 and 3 μg·L-1 (or 0.04 mg·kg-1 and 0.06 mg·kg-1) for AsO3-3 and AsO3-4 respectively,and determination limits (10 s) to be 0.01 mg·L-1 (or 0.2 mg·kg-1) for both anions.Precision of the determination was tested at the concentration levels of 1.50 mg·L-1 (AsO3-4) and 2.00 mg·L-1 (AsO3-3) by 7 determinations,and the RSD′s obtained were 1.3% and 2.2% respectively.Results of recovery test were in the range of 91.0%-98.9%.Comparative study of results obtained by this method with the results obtained by the atomic fluorescence spectrometric method was made,giving relative deviations in the range of 2.1%-12.9%.