A New Spectrophotometric Method for the Determination of Arsenic in Environmental and Biological Samples

Abstract

A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml⁻¹ of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×10⁴ l mol⁻¹cm⁻¹, 6.71×10⁻³ µg cm⁻², 0.02 µg ml⁻¹ and 0.08 µg ml⁻¹, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.

Keywords:

• Arsenic determination
• spectrophotometry
• iodate
• azure B

Acknowledgments

The authors thank the Microtron Centre of Mangalore University for the technical help.