Ultraviolet and visible absorption spectrophotometers
Spectrophotometers are instruments used to measure how much light of a particular wavelength is absorbed by a sample. Absorbance is the fraction of light that is absorbed by the sample. These devices are used in a variety of applications, including medical diagnostics, environmental monitoring, and materials analysis. Spectrophotometry is used to measure the absorbance of various molecules, such as proteins, pigments, and nucleic acids, at a certain wavelength or range of wavelengths. Ultraviolet (UV) and visible spectrophotometers are used to measure the absorbance of light in the UV and visible regions of the electromagnetic spectrum.
2.1 working principle of UV and visible spectrophotometer
The UV-vis spectrophotometer includes two main components: light sources and photodetectors, which measure the amount of light that is absorbed by the samples. In addition, it contains a sample chamber to hold the sample, a dispersing element to disperse the radiation, and a transmission grating to spread the sample light over a range of wavelengths.
A UV-vis spectrophotometer works by shining a light source—usually a monochromator or an acousto-optic modulator—through the sample in the chamber. The sample absorbs light at a certain wavelength, depending on its chemical composition. The unabsorbed light passes through the sample and is then captured by the photodetector. The photodetector measures the amount of light that has been absorbed by the sample, and this data is then used to calculate the absorbance at different wavelengths.
2.2 applications of UV and visible spectrophotometer
UV–visible spectrophotometers are used in many different scientific and industrial applications, including:
• Analyzing organic and inorganic compounds.
• Measuring the amount of certain proteins or other molecules in biological samples.
• Quality control for products such as paint, plastics, dyes, and food.
• Monitoring the catalytic activity of enzymes.
• Detecting environmental pollutants in water.
• Checking for contaminants in air.
• Analyzing chemical reactions.
2.3 Advantages and limitations of UV/visible spectrophotometers
One of the primary advantages of UV–visible spectrophotometry is that it is highly sensitive and can detect small changes in absorbance. It is also easy to use and can be used to analyze a wide variety of samples.
However, the technique has some drawbacks. For example, UV–visible spectrophotometry can only detect certain molecules, so it can’t be used to detect all species. In addition, it can’t be used to measure the concentration of a sample, as it can only measure absorbance. It is also less reproducible than fluorescence or atomic absorption spectrometry.
