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A flat sheet membrane desolvator (FSMD) was used to extend the applicability of a 120 W helium microwave induced plasma (He-MIP) to elemental analysis of organic-solvent-based samples and element selective liquid chromatographic detection. With the FSMD on-line, methanol could be nebulized with a sample flow rate of 1.5 ml/min and a carrier gas flow rate of 1.2 l/min without extinguishing the plasma. Under these conditions, applying desolvator countercurrent 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. Significant reductions in the emission intensities of C2 species at 436.5, 473.7, 512.9, and 563.6 nm were observed with the application of the FSMD. The 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 maximum 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 elements and solvent combinations were also examined. Element selective liquid chromatographic detection was preliminarily examined by monitoring 2,6-dichlorobenzene and 5,7-dichlorohydroxyquinoline at the 479.5 nm Cl atomic emission line. Chlorine detection limits in the 3–7 μg range (70–190 ng/s) were obtained. |
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