High Performance Liquid Chromatography coupled with Evaporative Light Scattering Detector is a universal technique for analyzing compounds that do not require any specific functionality or ionization capacity (such as the presence of chromophoric groups). The only requirement is that the compound does not evaporate in the detector unlike the solvent. This type of detector works in three stages: nebulization, evaporation and finally detection.
Leaving the column, the eluent charged with the sample is mixed with an inert carrier gas and passes through the nebulizer to produce a homogeneous aerosol. This fine mist consists of droplets of mobile phase containing the compounds of interest. The excess solvent drains out at the base of the nebulizer. This step is effective when a stable jet of droplets of uniform size is obtained.
The nebulized eluent is then entrained by the flow of inert carrier gas in a heating tube where the second step takes place: the evaporation of the mobile phase. As it progresses, the droplets become smaller and smaller until only tiny particles of dried analyte remain.
Then comes the last step where the solid particles enter a cell comprising a light source, laser or LED, and a photomultiplier. These lit particles deflect light according to their size. The intensity of the light scattered by the particles is directly related to the mass of the eluted compound. The deflected light is detected by the photomultiplier fixed at a defined angle (generally 45°) of the incident light.
The target sample includes lipids, amino acids, proteins, sugars and high molecular weight analytes