Analytical feasibility of graphite rod vaporization-helium microwave-induced plasma (GRV/He-MIP) for some nonmetal determinations

Trace level quantities of some nonmetallic elements are determined by coupling graphite rod electrothermal vaporization with a helium microwave-induced plasma. Microliter liquid samples of chlorides, bromides, iodides, sulfides, and ammonium nitrogen have been introduced into a grooved graphite rod, where they were dried, ashed, and vaporized into the plasma. The analytical performance of the GRV/He-MIP was found to be an excellent excitation source for dry analyte vapors. The graphite rod vaporization device is well suited for sample introduction for a low-power microwave-induced plasma. Analytical calibration curves were obtained that have linearities between 2.5 to 5 orders of magnitude. Detection limits of the technique for 10-μL aqueous sample solutions are reported in the lower nanogram region. The common anions and cations did not show significant interference effects on the determination of traces of these nonmetals.