Effects of a Membrane Desolvator on the Analytical Performance of a 120 W Helium Microwave-Induced Plasma: Aqueous Desolvation

Abstract

The effect of a flat-sheet membrane desolvator (FSMD) on the analytical performance of a low-power (120 W) He-MIP (helium microwave-induced plasma) is examined. Ultrasonic nebulization with conventional desolvation of an aqueous solution resulted in a dull, red, unstable plasma that was extinguished if the carrier gas flow rate was greater than 1.2 L/min. Using the FSMD with this system resulted in an enhancement of the plasma stability and a significant reduction of the reddish emission from hydrogen atoms. Also, without the FSMD, only weak chlorine emission signals were observed when 1000 ppm aqueous Cl solution was nebulized, but with the FSMD intense chlorine signals were observed with a detection limit of 1.0 μg/mL. Sensitivity improvement factors for Cu, B, P, Cd, and Pb ranged from 1.5 to 20. Greater improvements were seen for “harder to excite” elements.