hplc detectors

HPLC DETECTORS

BY:-VARUN GIRME

PAD:-DIODE ARRAY DETECTOR OR DAD OR HPLC PAD DETECTOR.

ELSD:-EVAPORATIVE LIGHT SCATTERING DETECTOR.

PAD:-DIODE ARRAY DETECTOR OR DAD OR HPLC PAD DETECTOR.

Diode array detector also referred to as a DAD detector or more specifically HPLC PAD detector.

PAD are used for obtaining spectral profiles from molecular mixtures or chromatographically separated samples.

Whether used to analyze molecules in a flow cell, static solution or solids they provide ultra-fast low noise spectral analysis.

Resolution determined by the number of diodes deployed over a specific wavelength range.

An HPLC photo diode array detector is coupled to elute of separation devices by molecular weight, hydrophobicity or ionic charge.

Certain HPLC PAD detectors handle the entire spectrum from the uv at 190nm to the near 1R at 1micron.

Other are specifically targeted to the uv visual or near 1R which up to 2048 elements provided for ultimate flexibility in resolution and multiplexing.

These mechanics provide high sampling speed of up to 190Hz and provide thermoelectric temp. control of sensor to limit noise.

ELSD:-EVAPORATIVE LIGHT SCATTERING DETECTOR.

Nebulization.The eluent from the HPLC system is forced

through a narrow orifice with a stream of gas flowingthrough a Venturi tube that sheaths the mobile phase toform small droplets that can be easily evaporated. Aflow of N2 at a pressure of 2–4 bar is typically used.

Vaporization. The mobile phase is removed from the nebulizer

droplets that contain the compound(s) of interest. The evaporation is performed by passing the droplets through a heated tube.

DetectionThe stream of solute particles that exits the

vaporization chamber enters the optical cell where the amount of light scattering, which is related to the mass of the compounds of interest, is measured. The sensitivity of the detector is ultimately determined by the number and shape of particles that are detected by the light scattering chamber in a given period

APPLICATION:-

Extremely small footprint to maximize availability bench space.

Wide gradient compatibility, no limitation on choice of solvent.

High sensitivity extremely low limits of detection.

Wide application range to cover very low to high molecular weight compounds.

Low dispersion minimum peak broadening for maximum resolution.

Rapid equilibrium fast set-up and high productivity.

Advanced easy to use instrument controls with built-in-safety.

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