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 liber ated iodine selectively oxidises leucocrystal violet to form crystal violet dye in the presence of sodium hydroxide. The dye formed shows maximum abso rbance at 592 nm. The detection limit of arsenic is 0.002 mu gmL(-1) and th e 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 absorptivit y was found to be 1.49 x 10(6) L mol(-1) cm(-1). The proposed method was su ccessfully applied for the determination of arsenic in various environmenta l and biological samples. The results are in good agreement with the standa rd reported method.