Photodiode array detector
The UV, VIS and hplc PDA are classified as absorbance detectors; they have a better sensitivity to the picogram (~ PG) levels and use them to detect compounds that have chromophore (light-absorbing compounds). UV is a widely used detector for ultraviolet spectroscopy as well as high-performance liquid chromatography.
The UV absorbance varies, depending on the mobile phase and the use of the wavelength. It is significant to select a suitable wavelength on the basis of the type of analyte or component. A typical UV detector permits to select the wavelength between 190nm and 400 nm. In contrast to a UV detector, a Visible (VIS) detector employs longer wavelengths, such as 400nm to 800 nm.
The detector that gives a broad wavelength selection, its covering range of UV-VIS (190-800 nm) called a UV/VIS detector.Conversely, the PDA detector passes a wide range of light through the sample and after that, the light is isolated into individual wavelengths subsequent to going through the sample. The spectrum of light is directed to an array of photosensitive diodes. Every diode can quantify a diverse wavelength which considers the monitoring of numerous wavelengths at a time. Generally, just 1-2 wavelengths are used during the chromatographic run.
The key difference between the UV and photodiode array detector in HPLC that the Photodiode array detector can measure the peak area and height of the specific peak of the sample or analyte on the different wavelengths in the range of 200 to 800 nm. While a UV detector can determine the peak area and height in just one or two separate wavelengths, but the wavelength must also be selected before injecting the sample solution in the HPLC injector.
