This document discusses two types of detectors used in HPLC - diode array detectors (DAD) and evaporative light scattering detectors (ELSD). The DAD or PAD is used to obtain spectral profiles of molecular mixtures or chromatographically separated samples. It provides fast, low-noise spectral analysis across a wavelength range determined by the number of diodes used. The ELSD works by nebulizing the eluent into droplets, evaporating the mobile phase, and detecting the amount of light scattered by the remaining solute particles, which is related to their mass. It offers high sensitivity with a wide application range and minimal peak broadening.

1. HPLC DETECTORS
BY:-VARUN GIRME

2.  PAD:-DIODE ARRAY DETECTOR
OR DAD OR HPLC PAD
DETECTOR.
 ELSD:-EVAPORATIVE LIGHT
SCATTERING DETECTOR.

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

5.  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.

6.  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.

7. ELSD:-EVAPORATIVE LIGHT
SCATTERING DETECTOR.

9. Nebulization.
The eluent from the HPLC system is forced
through a narrow orifice with a stream of gas flowing
through a Venturi tube that sheaths the mobile phase to
form small droplets that can be easily evaporated. A
flow of N2 at a pressure of 2–4 bar is typically used.

10. 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.

11. Detection
The 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

12.  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.

13.  THANK YOU