The spectrophotometer quantifies the concentration of a specific substance present in a sample by comparing the amount of light entering a sample with the amount of light leaving the sample at a specific wavelength. It can theoretically be used to measure any substance that absorbs light.

What is a spectrophotometer?

A spectrophotometer is a measuring instrument used to measure, as a function of wavelength, the relationship between values of the same photometric magnitude relative to two radiation beams. There are different spectrophotometer modalities, being atomic absorption or mass.

These devices have the ability to project a monochromatic beam of light through a sample and measure the amount of luminosity that is absorbed by that sample. The spectrophotometer can then provide us with information on the nature of the substance in the sample. Furthermore, it indirectly indicates that the amount of the substance concerned will be present in the sample.

Spectrophotometers work by isolating light at specific wavelengths from white light. A spectrophotometer breaks the light into its spectrum, using a color grid or similar system. Then a set of sensors reads each section of the spectrum, producing the spectral information.

Some of the essential components of the spectrophotometer are, for example, the light source that illuminates a given sample and which must meet a number of conditions such as, for example, directionality, stability, continuous spectral energy distribution. Typical sources are the tungsten lamp or xenon arc lamp.

The monochromator isolates the desired wavelength radiations that are reflected from the array. The detector, on the other hand, is the one that identifies radiation and in which two modalities are distinguished: those that respond to photons and those that respond to heat.

What considerations should you consider?

Spectrophotometry varies mainly by the type of light that is measured and the selection of the wavelength of the instrument. UV/Vis (ultraviolet/visible) light or fluorescent light can be used in spectrophotometry. A specific wavelength of UV/Vis light can be used to directly determine the concentration of a substance. It can also be used to determine the emission of fluorescent light and can be used to indirectly determine the concentration of a specific molecule.

Uses of the spectrophotometer

Spectrophotometers are widely used in biomedical sciences and life sciences research, which include academic and industrial research. Typical uses of the spectrophotometer are measurements of nucleic acids, protein, and bacterial density.

However, spectrophotometers are also widely used in a variety of industries including biotechnology, diagnostic and clinical testing, drug research, pharmaceutical research, chemical engineering, material science and agricultural research.

Spectrophotometry quantifies the concentration of compositions in a range of wavelengths. Thus, the researcher would select among the methods of classification depending on the type of information they want to obtain from the substance.