EVAPORATIVE LIGHT-SCATTERING DETECTION FOR MICROCOLUMN LIQUID-CHROMATOGRAPHY

A concentric micronebulizer for an evaporative light scattering detect or (ELSD) in microcolumn liquid chromatography was developed. The micr onebulizer uses a bellows regulating valve to control the effluent cap illary tip position relative to the nebulization gas. The modified ass embly also allows for control of the aerosol flight distance. Both par ameters can be optimized without having to stop effluent or nebulizati on gas flow. The micro-ELSD was evaluated for effluent flow rates rang ing from 0.5 to 10 mu L/min under reversed-phase conditions. The detec tor drift tube can be operated at ambient temperatures under aqueous c onditions without a significant decrease in signal-to-noise ratio. In the flow injection mode the limit of detection for glucose is 50 pg. T he response of the detector was linear over two different ranges, from 1 to 25 ng and from 35 to 461 ng. In this article, the construction o f the micronebulizer is described and the parameters (drift tube tempe rature, nebulizer gas flow rate, effluent capillary position, aerosol flight distance, effluent flow rate, and mobile phase composition) tha t influence detector response are studied. (C) 1998 John Wiley & Sons, Inc.