Abstract: Arsenic (III) is a very toxic element that sometimes found in ground or waste waters which has harmful effect on human health. It is a natural component of the Earth’s crust, generally found in trace quantities in all rock, soil, water and air. However, concentrations may be higher in certain areas due to either natural conditions or human activities. Trivalent arsenic compounds generally are more toxic than the pentavalent compounds. In this study, an automated dynamic headspace liquid phase microextraction technique is coupled with electro chemical hydride generation to determine trace amount of arsenic As (III) in environmental samples by UV–Vis spectrophotometry. The investigated method is based on electrochemical reduction of As to Arsine (AsH3) in acidic media and on the subsequent reaction of AsH3 with silver diethyl dithiocarbamate (AgDDC) to give red complex. The optimizing of the process was performed by simultaneous varying of influencing parameters with the aid of central composite design (CCD). Under optimum conditions linear response from 75 ng mL−1 to 1000 ng mL−1 with R2 = 0.9977 and limits of detection of 22 ng mL−1 were achieved. The method proved to be applicable in different types of waters. This method benefits main advantage including, dynamic automated of the method led to sensitivity, higher enrichment factor, good replicability and ease of operation.

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