Photometry Absorption

Absorption photometry: measuring the light absorption of objects

Absorption photometry (or spectrophotometry) is an analysis method based on measuring light absorption by an object. It is widely used in laboratory practice, in particular, for the quantitative analysis of biologically active substances.

The essence of the method is that light passes through a solution or other object being analyzed, and its intensity is measured before and after passing through the object. The difference between the measurements is due to the fact that the object absorbs some of the light, while the rest passes through it and reaches the detector.

To measure light absorption, a spectrophotometer is used - a device that measures the light passing through the object being analyzed at various wavelengths. This allows us to obtain the absorption spectrum of the object, i.e. dependence of the degree of light absorption on wavelength.

Absorption photometry is one of the most accurate methods for the quantitative analysis of biologically active substances, for example, proteins, nucleic acids, enzymes and other organic molecules. It is also widely used in the analysis of water and other liquids, including drugs.

In addition, absorption photometry can be used to measure the concentration of a substance in a solution, as well as to determine the kinetic parameters of reactions, such as the reaction rate and rate constant.

In conclusion, absorption photometry is an important analysis method that provides information about the properties of an object based on its light absorption spectrum. It is widely used in laboratory practice and helps solve many problems in the fields of biology, chemistry and pharmacology.

Photometry is a set of methods and instruments for measuring light and energy parameters of optical radiation, as well as images of objects in monochromatic or white light. The process is carried out using special photometric devices. Certain types of photometry acquire their own name and formulation, for example spectrophotometry, pyrometry, photographic materials science.

Absorption photometry - F. (from Latin absorbere - to absorb), is based on recording light absorption by the substance under study. Used to measure light absorption coefficients of LCS and extinction coefficients of dilute solutions. In the optical spectrum, photometer readings are proportional to the value of Dl, defined as the difference between the Dl values ​​in the absorbing and non-absorbing regions of the spectrum. Typically, this interval is set symmetrically on both sides of the maximum emission of the solution in the wavelength region where there are no absorption bands. Conventional photometers allow recording only one of the forms of spectra - light absorption curves (LACs), which represent the dependence logI=f(λ). They can appear as a line (monochromatic light), a broadened peak, or several broadened peaks. The absorption band is characterized by the position of the maximum on the wavelength scale λm and the depth p and is characterized by the width Δλ.

It is used in various fields of science, technology and industry, especially in chemistry, physics and biology. Absorption photometers are used in medicine to determine the content of hemoglobin and red blood cells in the blood, to determine the amount of proteins in biological material. Absorption photometry is used in laboratory equipment such as spectrophotometers and photoelectrocolorimeters.