DETERMINATION OF BROMIDE, CHLORIDE, AND FLUORIDE IN CIGARETTE TOBACCO BY ION CHROMATOGRAPHY AFTER MICROWAVE-INDUCED COMBUSTION

microwave-induced combustion (MIC) method was applied for cigarette tobacco digestion and further determination of bromide (Br), chloride (Cl), and fluoride (F) by ion chromatography (IC). Samples (up to 500 mg) were combusted at 20 bar of oxygen. Combustion was complete in less than 30s, and analytes were absorbed in (NH4)(2)CO3 solutions. A reflux step, not available in other systems, was applied to improve analyte absorption. Absorbing solution with 50 mmol L-1 (NH4)(2)CO3 was selected because it showed recovery close to 100% for samples containing spikes of halogens. Accuracy of the proposed procedure was evaluated by analysis of certified reference materials and the agreement was better than 97% for all analytes using 50 mmol L-1 (NH4)(2)CO3 as absorbing solution and 5 min of reflux. Temperature during combustion was higher than 1400 degrees C and the residual carbon content was always lower than 1%. With the use of the MIC system, up to eight samples could be processed simultaneously, and a single absorbing solution was suitable for all analytes. Limits of quantification by MIC and further IC determination were 0.50, 0.20, and 0.10 mu gg(-1) for Br, Cl, and F, respectively.