Determination of Arsenic in Drinking Water Samples by Electrothermal Atomic Absorption Spectrometry after Preconcentration Using the Biomass of Aspergillus niger Loaded on Activated Charcoal

A simple, fast, and sensitive method for determination of total arsenic in drinking water sample by ETAAS after solid phase preconcentration has been developed. The dead biomass of A. niger loaded on activated charcoal has been applied as bioadsorbent for preconcentration step. The effects of parameters such as pH, type and concentration of eluent, biosorption time, sample volume, and effect of interfering ions have also been studied. Under the optimum condition, the enrichment factor of 10 for the analyte has been obtained. The accuracy of the method has been investigated by the recovery of spiked standards and the recovery percents between 99 and 102% have been achieved. Total amount of arsenic was determined by reducing As (V) to As (III) with potassium iodide (KI) and ascorbic acid in HCl solution. Under the optimum conditions, for 400 mL of drinking water samples, the detection limit (3 sigma) and linear range were achieved 1 ng/mL and 5-100 ng/mL, respectively. The relative standard deviation for ten determinations of a spiked sample with concentration of 10 ng/mL As was 3.2%.