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Equilibrator for Use in Evaporative Light Scattering Detection

Detailed Technology Description

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*Abstract

UM No. 06UMS067EQUILIBRATOR FOR EVAPORATIVE LIGHT SCATTERING DETECTIONIn HPLC, liquid exiting the column consists of a mixture of one or more solvents and one or more substances to be determined in the analysis. The liquid mixture is called the “mobile phase” and the substances to be measured are called “analytes.” The analytes are separated from one another as they pass down the column so that they exit the column at different times. Thus at any instant, the column effluent will consist of either pure solvent or solvent plus one of the analytes. When the liquid enters the ELSD, it is fed through a nebulizer along with a gas such as nitrogen, and it exits the nebulizer as a spray of fine droplets. The droplets are then allowed to pass through a drift tube carried by the stream of nitrogen gas. As the droplets pass through the drift tube, the solvent molecules evaporate, leaving any analyte present in the form of small particles. The particles, evaporated solvent and carrier gas then pass through a light beam, where they cause some of the light to be scattered. This scattered light is sensed by a photodetector. Light that is scattered by solvent molecules and carrier gas produces a background or baseline in the analysis. Thus an increase in the amount of scattered light, above the background scattering, is indicative of the presence of analyte particles in the HPLC effluent. As each analyte passes out from the HPLC column, a peak is observed above the baseline of the ELSD output signal. The signal vs. time is called a chromatogram.In order to detect a small amount of analyte, one must be able to observe a small peak above the baseline. This means that the baseline must exhibit very little noise. One persistent cause of baseline noise is the presence of solvent droplets due to incomplete solvent vaporization. These droplets readily scatter light and appear randomly, so that they cause random variations (noise) in the baseline.The situation will be greatly improved if the drift tube evaporation efficiency can be increased so that solvent droplet formation can be minimized. To this end, researchers at the University of Missouri-St. Louis have devised a new unit, designed to replace the drift tube. Present drift tubes are either straight tubes or coiled tubes. The new unit, called an equilibrator, offers smaller device size and higher efficiency.CONTACTTo discuss this opportunity, please contact:Craig WeilbaecherLicensing & Business Development AssociateUniversity of Missouri-St. Louisweilbaecherc@umsl.edu314-516-4248

*Principal Investigator

Name: David Larsen

Department:

Name: Zhi Xu

Department:

Country/Region

USA