by An evaporative light scattering detector (ELSD) is a detector used in conjunction with high-performance liquid chromatography (HPLC), Ultra high-performance liquid chromatography (UHPLC), Purification liquid chromatography such as flash or preparative chromatography, countercurrent or centrifugal partition. It is commonly used for analysis of compounds where UV detection might be a restriction and therefore used where compounds do not efficiently absorb UV radiation, such as sugars, antivirals, antibiotics, fatty acids, lipids, oils, phospholipids, polymers, surfactants, terpenoids and triglycerides. ELSDs is related to the charged aerosol detector (CAD) and like the CAD, falls under the category of destructive detectors.An evaporative light scattering detector (ELSD) is able to detect all compound which are less volatile than the mobile phase, i.e. non volatile and semi-volatile compounds.
Principle of ELSD detector:
The principle of evaporative light-scattering detectors (ELSD) is to nebulize the column effluent into droplets that are carried by a nebulizing gas in an evaporator (or drift) tube and then directed toward a light beam. The intensity signal is related to solute concentration in the eluent.
What does ELSD measure:
The evaporative light scattering detector (ELSD), otherwise known as an Evaporative Mass Detector, is an aerosol-based HPLC detector suitable for the detection of non-volatile sample components in a volatile eluent.
Difference between ELSD and CAD detector:
ELSD uses reflected and scattered light and a sensitive photomultiplier to measure analyte concentrations.
CAD uses a high-voltage corona needle to charge nitrogen gas molecules which collides with analyte particles resulting in the formation of charged particles
Difference between ELSD and RI detector:
An ELSD has a sensitivity roughly 10 times higher than an RI detector, but has a slightly low sensitivity to low molecular components due to their small size. An ELSD is used mainly to detect non-UV-absorbing components. Attention should be given to the fact that nonvolatile salts cannot be used as the eluent
Why ELSD is used in HPLC
An evaporative light scattering detector (ELSD) is a universal HPLC detector whose detection principle is based on the phenomenon of light scattering, which occurs from particles of residual non-volatile components after removing the volatile mobile phase using a combination of heat and gas nebulization.
Is ELSD a universal detector
The feature of an evaporative light scattering detector (ELSD) is to be universal. In contrast to other detectors such as UV, RI and mass detectors, compounds can be detected up to 100%.
Detection limit for ELSD
ELSD is limited to (1–50 ng on-column) in the best cases. More commonly, 50–100 ng on-column is a generally observed limit of detection.
Cleaning Procedure for ELSD detector:
Cleaning Procedure:
- Put the ELSD into RUN mode.
- Set the Evap and Neb temperatures to 40°C.
- Remove the column from the system. Pump strong solvent or a mixture of solvents at 5 ml/min for 3 hours. Or 1ml/min at overnight
