Analysis of Arsenic from water by Spectrophotometric method

Arsenic compounds are widely used, have been recognized as toxicants. The arsenic contaminated drinking water Arsenic from water may be determined by many methods such as atomic adsorption spectroscopy (AAS), Inductively coupled plasma atomic emission spectroscopy (ICP-AES), electrochemistry and spectrophotometry with silver diethyldithiocarbamate. This article presents a study on the arsenic determination from water by spectrophotometric method based on molybdate reagent. This method poses high sensitivity and selectivity but has not been studied in detail. The obtained results have sugested the experimental optimum conditions for arsenic determination by spectrophotometric method using molybdate reagent. The method consists of three steps (i) arsinization of arsenic to producing AsH3, (ii) AgNO3, H2O2reagents oxidized AsH3 to producing As(V) and (iii) the reaction of As(V) with molybdate  reagent to produce molybdenum blue complex. The absorbance of molybdenum blue complex at the wave length of λ = 878 nm has been used for arsenic determination. The LOD and LOQ of the method are 2 and 7ppb respectively