Evaporative light scattering detection for microcolumn liquid chromatography

A concentric micronebulizer for an evaporative light scattering detector (ELSD) in microcolumn liquid chromatography was developed. The micronebulizer uses a bellows regulating valve to control the effluent capillary tip position relative to the nebulization gas. The modified assembly also allows for control of the aerosol flight distance. Both parameters can be optimized without having to stop effluent or nebulization gas flow. The micro-ELSD was evaluated for effluent flow rates ranging from 0.5 to 10 μL/min under reversed-phase conditions. The detector drift tube can be operated at ambient temperatures under aqueous conditions without a significant decrease in signal-to-noise ratio. In the flow injection mode the limit of detection for glucose is 50 pg. The response of the detector was linear over two different ranges, from 1 to 25 ng and from 25 to 461 ng. In this article, the construction of the micronebulizer is described and the parameters (drift tube temperature, nebulizer gas flow rate, effluent capillary position, aerosol flight distance, effluent flow rate, and mobile phase composition) that influence detector response are studied.