Spectrophotometric determination of carbon tetrachloride via ultrasonic oxidation of iodide accelerated by dissolved carbon tetrachloride.

Ultrasonic oxidation of iodide was investigated in the presence of carbon tetrachloride (CCl4). The ultrasonic oxidation of potassium iodide led to formation of iodine and then I3(-) in the presence of excess iodide, and the generated I3(-) shows strong UV absorption with a molar absorptivity of 2.31x10(4) L mol(-1) cm(-1) at the maximum absorption wavelength of 351 nm. The ultrasonic oxidation of iodide was found to be significantly promoted by a small addition of CCl4, and it was further found that the generation rate was increased with the amount of CCl4 added. This can be used to analyze the level of CCl4 dissolved in aqueous solutions. Under optimum conditions, the concentration of generated iodine (or its absorption at 351 nm) was found to correlated linearly with the concentration of CCl4 in the range of 0.2-50 mg L(-1) (detection limit = 0.09 mg L(-1), R2 = 0.999). As an alternative indirect spectrophotometric method of CCl4 determination, the proposed method was successfully applied to determine the concentrations of CCl4 in several practical samples, showing merits of being sensitive and simple of operation.