PDA (Photo Diode
Array) Detector:
The Photo
Diode Array (PDA) detector was invented by Dr. David Marr, a scientist and
entrepreneur who founded the company, Spectra-Physics, in 1961. The PDA
detector was introduced in 1986 as a new technology for spectroscopy and has
since become a popular detection method for High-Performance Liquid
Chromatography (HPLC). The PDA detector is able to detect and record multiple
wavelengths of light simultaneously, allowing for the generation of a complete
UV-Vis absorption spectrum of a sample as it elutes from the column. This makes
it a powerful tool for the identification and quantification of complex
mixtures of compounds in various fields, including pharmaceuticals, food, and
environmental analysis.
A PDA (Photo
Diode array) detector is a type of UV-visible detector that is commonly used in
high-performance liquid chromatography (HPLC) and other analytical chemistry
applications.
PDA detectors
work based on the same principles of absorbance and transmittance of light as
other UV-visible detectors. However, PDA detectors are equipped with an array
of photodiodes that detect multiple wavelengths of light simultaneously, making
them more versatile and sensitive than single-wavelength detectors.
When the
light source emits UV or visible light onto the sample cell, the sample absorbs
some of the light, causing a reduction in the intensity of the transmitted
light. The light that passes through the sample is then dispersed by a
diffraction grating into a spectrum of different wavelengths.
The dispersed
light then falls onto the photodiode array, where each photodiode detects the
intensity of light at a specific wavelength. By analyzing the intensity of
light detected by each photodiode, the PDA detector can generate a full
UV-visible spectrum of the sample in real-time.
This allows
for more detailed and accurate identification and quantification of individual
components in a sample, as well as the detection of impurities or other
substances that may not be detected using a single-wavelength detector.
PDA detectors
are widely used in HPLC, where they are used to monitor elution of analytes
from the chromatography column, identify peaks and components in complex
samples, and quantify the concentration of individual components. They are also
used in other applications such as in the analysis of natural products,
pharmaceuticals, and food and beverages.
Range of PDA Detector used in HPLC
analysis:
PDA
(photodiode array) detectors are commonly used in HPLC (high-performance liquid
chromatography) to detect and quantify analytes in a sample. PDA detectors are
equipped with an array of photodiodes that detect multiple wavelengths of light
simultaneously, allowing for the generation of a full UV-visible spectrum of
the sample in real-time.
The range of
the PDA detector in HPLC typically covers the UV-visible range, which is
approximately 190-800 nm. However, the specific range of the PDA detector can
vary depending on the manufacturer and model.
Most PDA
detectors used in HPLC are equipped with a deuterium lamp as the UV light
source, which covers the UV range from approximately 190-400 nm. The visible
range from approximately 400-800 nm is covered by a tungsten lamp.
The range of
the PDA detector is important in HPLC because it determines the sensitivity and
accuracy of the detection method. The broader the range of the PDA detector,
the more versatile it is for analyzing a wider range of analytes with different
absorption spectra.
Abhishek Singh is the author of Pharma technical support. He is pharmaceutical professionals, having experience of more than 12 years in Quality.