ANALYTE VOLATILIZATION PROCEDURE FOR THE DETERMINATION OF LOW CONCENTRATIONS OF CHLORINE BY ATMOSPHERIC-PRESSURE HELIUM MICROWAVE-INDUCED PLASMA-ATOMIC EMISSION-SPECTROMETRY

A simple method is described for the generation of a continuous flow o f volatile chlorine by the oxidation of aqueous chloride for the deter mination of low concentrations of chlorine by atmospheric-pressure hel ium microwave-induced plasma atomic emission spectrometry (He MIP-AES) . The chlorine atom emission line at 438.976 nm and ion emission lines at 479.454 and 481.006 nm were selected as the analytical lines of in terest. Of the various oxidation reactions investigated,two analyte vo latilization reactions with potassium permanganate and perbromate in c ombination with sulfuric acid were found to be the most appropriate fo r the generation of elemental chlorine. The gaseous chlorine is separa ted from the solution in a simple gas-liquid separator, dried with con centrated sulfuric acid and swept into the MIP with helium carrier gas for analysis. The best attainable detection limits (3 sigma criterion ) for chlorine at 438.976, 479.454 and 481.006 nm with the use of pota ssium permanganate as an oxidant were found to be 29.9, 6.8 and 12.3 n g ml(-1), respectively. Typical calibration graphs obtained under the optimized experimental conditions are rectilinear over approximately t hree orders of magnitude of concentration. The present method has succ essfully been applied to the determination of chlorine as chloride in several water samples. (C) 1998 Elsevier Science B.V. All rights reser ved.