A spectrophotometer is an instrument widely used in laboratories to measure the absorbance of a sample, depending on the wavelength of electromagnetic radiation, and thus know the concentration of substances in a solution.
The importance of a spectrophotometer lies in the fact that it is used in the laboratory with the main purpose of diagnosing, taking into account the properties of light and the interaction with other substances. In general, this equipment is made up of 4 main parts: a source, a monochromator, a beam splitter, a sample area and a detector. It also has optical elements such as lenses or mirrors, which transmit light throughout the entire equipment.
Spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed or transmitted through a sample compared to a blank or reference sample. This property is influenced by the composition of the sample, potentially providing information about what is in the sample and at what concentration.
How does a spectrophotometer work?
There are several types of spectrophotometers. These are classified according to the type of sample analyzed; there are atomic absorption and molecular absorption (UV-VIS spectrophotometer). A UV-VIS spectrophotometer is based on the absorption process of ultraviolet-visible radiation (radiation with a wavelength between 200 and 780 nm) by a molecule. The absorption of this radiation causes the promotion of an electron to an excited state. The electrons that are excited by absorbing radiation of this frequency are the bonding electrons of the molecules, so the absorption peaks can be correlated with the different types of bonds present in the compound. Due to this, UV-VIS spectroscopy is used for the identification of the functional groups present in a molecule. The bands that appear in a UV-VIS spectrum are wide due to the superposition of vibrational and electronic transitions.
Light has a certain amount of energy that is inversely proportional to its wavelength. Therefore, shorter wavelengths of light carry more energy and longer wavelengths carry less energy.
Applications of a spectrophotometer
Spectrophotometers are used in many laboratories in different areas of science ranging from analyzing bacterial culture, drug identification, and nucleic acid purity testing and quantification, to quality control in the beverage industry and chemical research. .