DIRECT DETERMINATION OF AQUEOUS CARBON, PHOSPHORUS AND SULFUR USING A KILOWATT-PLUS HELIUM MICROWAVE-INDUCED PLASMA SYSTEM WITH ULTRASONIC NEBULIZATION

Determination of carbon, phosphorus and sulfur in aqueous solutions was performed by direct sample introduction with an ultrasonic nebulizer into a kilowatt-plus (1600 W) helium microwave-induced plasma. Emission was observed in the ultraviolet-visible spectral region. Unlike metals in aqueous solution, common forms of non-metals in aqueous solution exhibit significantly different vaporization characteristics in the nebulizer. In this study, the effects of molecular forms of aqueous carbon, phosphorus and sulfur upon sample introduction and resultant emission intensities were observed. Analytical signal enhancements were observed when the solution chemistry was adjusted to produce volatile analyte species. The capabilities of the high-power plasma for atomization and excitation of non-metals were demonstrated by the detection of sulfur emission from aqueous sulfate solutions. Other studies include the examination of detection limits, linear responses and matrix effects.