Then, 10mL of 1 molL?1 H2SO4 was added to the beaker and the contents were heated at 100��C for 1h and diluted to 50mL. FivemL aliquots of these solutions were used to estimate the arsenic content.2.4. ChemicalsThe commercially procured laboratory chemicals for which the assay has been specified have been used to quantify the arsenic content. One gram of sample was dissolved in water Tofacitinib Sigma and then treated with 5mL each of concentrated nitric acid followed by H2O2. The solutions were diluted to 100mL, and 5mL aliquots were used for the analysis of total arsenic content.2.5. Amaranth Dye1g of dye sample was dissolved in water and then, treated with 5mL each of concentrated nitric and H2O2. The pH of the solution was adjusted to 5 by adding acetate buffer solution and made up to 100mL.

Then, 5mL aliquot of diluted sample was used for the analysis.2.6. ProcedureSuitable aliquots of arsenate solution (arsenic concentration 10?200 ngmL?1) were taken in 10mL volumetric flasks. Then, 2mL of 1.25 molL?1 sulfuric acid, 0.2mL of 0.008molL?1 antimony (III), 1.2mL of 0.015molL?1 ammonium molybdate, and 0.5mL of 0.01molL?1 ascorbic acid were added and allowed for 10 minutes for the formation of arsenomolybdenum blue complex. Then, 2mL of Triton X-114 (4% v/v) has been added and the solutions were diluted to the mark. These solutions were transferred into 30mL centrifuge tubes and phase separation was achieved by centrifuging them at 3800rpm for 5min. The centrifuge tubes were cooled in an ice bath to harden the viscous phase of the surfactant-rich micellar phase.

Then, the aqueous phase was separated by simple decantation method. The surfactant-rich micellar phase was homogenized by the addition of ethanol and made up to 5mL. The absorbance values were measured at 690nm against the reagent blank.3. Results and DiscussionThe proposed method is based on the reaction of arsenic (V) with molybdate to form arsenomolybdate and its reduction to arsenomolybdenum blue complex in presence of a reducing agent. This reaction has been proposed based on the phosphate’s reaction with molybdate to form phosphomolybdenum blue in acidic medium and its application to water samples through cloud point extraction [15]. The reaction has been explored to develop a simple and sensitive spectrophotometric method to measure arsenic at nanogram level concentrations.

The arsenomolybdate formed in acidic medium with molybdate can be reduced to arsenomolybdenum blue complex with antimony (III) in presence of ascorbic acid as reducing agent. The blue-colored complex exhibited absorption maximum at 840nm in aqueous condition. Surfactants have been extensively used to sensitize the reaction Drug_discovery or to separate the analyte phase without using organic solvent as a medium. Hence, a nonionic surfactant has been used to extract the arsenomolybdenum blue complex by cloud point method at room temperature.