Determination of carbon in aqueous solutions by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry with gas-phase sample introduction technique.

A trace amount of carbon was determined by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry (He-MIP-AES) with gas-phase sample introduction technique. This method was applied for the generation of a continuous flow of carbon dioxide by the acidification of carbonate ion and hydrogen carbonate ion for the determination of carbon. The generated carbon dioxide was separated from the solution by a simple gas-liquid separator, dried with a desiccant and swept into the MIP with helium carrier gas for analysis. Of the acids and drying agents investigated, hydrochloric acid for acidification and anhydrous calcium chloride as a desiccant were found to be the most appropriate for the generation of carbon dioxide. Under the optimized experimental conditions, the best attainable detection limits at C (I) 193.09 and C (I) 247.86 nm lines were 7.89 and 8.10 microg/l with linear dynamic ranges of 100 to 10,000 and 100 to 20,000 microg/l for carbon, respectively. The presence of many diverse elements and ions was found to cause a more or less depressing interference by the proposed technique. However, no interference was observed from the following elements and ions: Ca, K, Rb, Br-, Cl-, F- and I-. Finally, the present method has been applied to the determination of carbon in several water samples.