Liquid Chromatography Detectors - The Evaporative Light Scattering Detector > Page 74

 

Courtesy of Polymer Laboratories Inc.

Figure 49 The Sensor of a Commercial Evaporative Light Scattering Detector

Detector sensitivity is claimed to be between 10 and 20 ng of solute. However, in these terms it is difficult to compare with other detectors. The great advantage of the detector, however, is its catholic response and that its output is linearly related to the mass of solute present. However, the magnitude of the response does vary widely between different substances.

A diagram of the sensor of the evaporative light scattering detector manufactured by Polymer Laboratories is shown in figure 49. The eluent is atomized in a stream of nitrogen and the finely divided spray passes down a heated chamber during which time the solvent is evaporated. The removal of the solvent produces a stream of particles which then pass through a collimated beam of light. The scattered light at an angle to the incident light is focused onto a photomultiplier tube and the output is processed in an appropriate manner electronically.