PDA detectors are common in many research labs that utilize HPLC instruments. Below, we’ll briefly summarize PDA detectors, how they’re used in HPLC, and the advantages they offer over other detectors.
What Is an HPLC Detector?
First, let’s understand the role of a detector in HPLC. Detectors analyze the components of the eluted mixture after it passes through the HPLC column. Different types of detectors are chosen according to the chemistry the researchers wish to observe.
Detectors can measure the sample’s absorbance, molecular weight, fluorescence, and other qualities, depending on what the user wants to detect in the eluted mixture. Most detectors measure absorbance, which is what PDA and UV/Vis detectors are—the absorbance of light by a liquid flowing past.
What Is a PDA HPLC Detector?
A common type of detector in HPLC is the photodiode array (PDA) detector, sometimes called a diode array detector (DAD). With a PDA detector, researchers can gather information about the sample separations’ identity, quantity, and purity as they exit the HPLC column.
PDA uses reverse optics, meaning the full spectrum of light from a source interrogates the sample as it traverses a flow cell. The light passed through the sample is isolated into individual wavelengths, and the spectrum is directed to an array of photosensitive diodes.
What Are the Benefits of a PDA Detector?
Many research labs favor PDA detectors for several reasons, but it’s generally due to their versatility. PDA detectors provide fast and wide spectral analysis of molecules in a flow cell, static solutions, or solids.
PDA detectors offer a greater ability to look at all wavelengths of the spectrum than UV/V detectors. While the PDA can measure the peak area and height of a peak in the sample on wavelengths in the 200-800 nm range, UV detectors are limited to a wavelength range that’s only a fraction of the PDA.
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