ABSTRACT
The principle of the evaporative light scattering detector (ELSD) was introduced in 1978 by J. M. Charlesworth. The ELSD detects the light scattered by solutes after the mobile phase is sprayed and partially or totally evaporated. Many principles may be used to create a liquid aerosol from the mobile phase leaving the column, all commercial detectors use a pneumatic nebulizer. Pneumatic nebulizers use a compressed gas such as nitrogen or air to spray the mobile phase using the Venturi effect. Solvent evaporation arises in a heated tube located between the nebulizer and the detection cell. Two types can be found in commercial ELSD: either a short direct tube of about 20–30 cm long or a 1–2 m coiled tube. The detector response is a complex function which depends on the intensity of light scattered by solute particles from the third aerosol. The effect of gas pressure and mobile phase flow rate on ELSD response can be understood from Nukiyama–Tanasawa equation.
