A sensitive colorimetric method for the determination of arsenic in environmental and biological samples

Results of a thorough study and application of leucocrystal violet for the determination of arsenic in parts per million (ppm) levels in environmental and biological samples is described here. The proposed method is based on the reaction of arsenic with potassium iodate to liberate iodine. The liberated iodine selectively oxidises leucocrystal violet to form crystal violet dye in the presence of sodium hydroxide. The dye formed shows maximum absorbance at 592 nm. The detection limit of arsenic is 0.002 mu gmL(-1) and the method obeys Beer's law over the concentration range of 0.1 mu g - 1.0 mu g of per 25 mL of final solution (0.004 - 0.04 ppm). The molar absorptivity was found to be 1.49 x 10(6) L mol(-1) cm(-1). The proposed method was successfully applied for the determination of arsenic in various environmental and biological samples. The results are in good agreement with the standard reported method.