A powerful tool used in clinical, pharmaceutical, and biochemical laboratories, the UV-Vis spectrophotometer is an instrument that detects metal ions and organic compounds in a solvent via a light source that passes through its sample chamber. The intensity of the light is measured by the diffraction of the light beam into a spectrum of wavelengths, detecting the intensities with a charge-coupled device, and displaying the results as a graph on the detector and then on the display device.
Ultraviolet-visible spectrophotometry is the method of choice in most laboratories concerned with the identification and measurement of organic and inorganic compounds in a wide range of products and processes such as nucleic acids and proteins, foodstuffs, pharmaceuticals and fertilizers. Advantages of the UV-Vis spectrophotometer include:
- Ease of use
- Speed of the analysis
- Wavelength accuracy
- Photometric accuracy
- High sensitivity for detecting organic compounds
- Simplistic design
There are single beam and double beam spectrophotometers. In the single beam instrument, all of the light passes through the sample holder. A reference is placed in the sample holder to make measurements. Effects from the solvent and the cell are removed by subtracting this reference value from subsequent sample measurements.
In the split beam design, one beam illuminates the reference cell holder and the other beam illuminates the sample. Reference correction can be applied continually throughout a measurement with this configuration and this is typically used in kinetics measurements for which the sample and reference change over time. Double beam instruments offer the highest accuracy.
Sample analysis using UV-Vis is a very quick process compared to other methods of sample detection. The SQ4802 UV/Vis spectrophotometer from industry leader Unico is ideal for performing routine applications such as spectrum scanning, quantitative analyses, multiple components DNA/Protein, and kinetics. Featuring a 1.8 nm fixed bandwidth and providing measurements in the wavelength range of 190nm to 1100nm, this advanced device comes with optional PC download software and PC Windows® application software, and a solid silicon photodiode detector. Other models from Unico include the single beam SQ2800 UV/VIS, 110V-220V and the SQ3802 UV/VIS, 110V-220V with double beam design.
As designs and models vary, the manufacturer’s manual and the lab’s standard operating procedures should be followed for error-free operation and maintenance. In addition to calibration, instruments should be periodically checked for accuracy. Wavelength calibrations and linearity checks are recommended for UV/Vis spectrophotometers.