Membrane desolvation for the analysis of organic solutions and liquid chromatographic samples with low power helium microwave induced plasma atomic emission detection

A flat sheet membrane desolvator (FSMD) was used to extend the applicabilit y of a 120 W helium microwave induced plasma (He-MIP) to elemental analysis of organic-solvent-based samples and element selective liquid chromatograp hic detection. With the FSMD on-line, methanol could be nebulized with a sa mple flow rate of 1.5 ml/min and a carrier gas flow rate of 1.2 l/min witho ut extinguishing the plasma. Under these conditions, applying desolvator co untercurrent gas flows in the range 0-8 l/min restored of the original pink color of the pure helium MIP from the bluish-green caused by methanol. Sig nificant reductions in the emission intensities of C-2 species at 436.5, 47 3.7, 512.9, and 563.6 nm were observed with the application of the FSMD. Th e intensities of chlorine analyte emission lines at 479.5, 481.0 and 481.9 nm increased with increasing countercurrent gas flow rates and reached a ma ximum intensity with a flow rate of 5.0 l/min. Detection limits for Cl and Pb were 2.1 and 0.1 ppm using a 1 m focal length monochromator. Other eleme nts and solvent combinations were also examined. Element selective liquid c hromatographic detection was preliminarily examined by monitoring 2,6-dichl orobenzene and 5,7-dichlorohydroxyquinoline at the 479.5 nm Cl atomic emiss ion line. Chlorine detection limits in the 3-7 mu g range (70-190 ng/s) wer e obtained. (C) 1999 Elsevier Science B.V. All rights reserved.