Moderate volatility analyte transport behavior with membrane desolvation reversed-phase liquid chromatography-helium microwave-induced plasma atomic emission spectroscopy

The transport behavior of moderately volatile analyte in a membrane desolva tion system is examined. With the goal of atomic emission determination of liquid chromatographic analytes, a tubular polytetrafluoroethylene membrane desolvator interface was used to enhance the performance of a 120 W helium microwave-induced plasma atomic emission detector. To monitor organo-chlor ine compounds, Cl emission was observed at 479.5 mn. Membrane desolvator co nditions such as temperature, solvent composition and counter current gas f low were optimized. Converse to required conditions for non-volatile inorga nic compounds, semi-volatile organic compound transport was maximized at lo wer membrane desolvator temperatures. Analyte transport was enhanced by mod ifying the solvent with dilute H2SO4. Low vapor pressure H2SO4 minimized an alyte diffusion across the membrane and helped linearize the calibration pl ot. The detection limit of 2,6-dichlorobenzamide in pure methanol using ult rasonic nebulization and membrane desolvation with microwave-induced plasma detection was 2 ppm. Chromatographic separation and detection was demonstr ated with 2,6-dichlorobenzamide and 4-chlorobenzamide. (C) 2001 Published b y Elsevier Science B.V.