How to measure hydroxyl radicals, an introduction to hydroxyl radicals

1. Spin trapping—ESR method.

Electron spin resonance (ESR) is also known as electron paramagnetic resonance.

EPR (electron paramagnetic resonance) is a method that can directly detect and identify free radicals, and its determination process needs to be synchronized with the generation of the measured free radicals, so there are great restrictions on the preparation and detection of samples. Spin trapping technology uses an appropriate spin trap to combine with active short-lived free radicals to generate relatively stable spin adducts, and the structure of the original active radicals can be inferred according to the ESR spectral parameters of the spin adducts.

2. High performance liquid chromatography.

High Performance Liquid Chromatography (HPLC) can be used to indirectly determine free radicals. During the determination process, it is necessary to select the appropriate compound to capture the free radicals in the tested system to generate a product with certain stability that can be separated and detected by liquid chromatography, and then determined by HPLC.

Dimethyl sulfoxide is used.

Traps hydroxyl radicals.

HPLC assay method.

Salicylic acid is used.

HPLC method for the determination of hydroxyl radical trapping.

3. Spectrophotometry.

In the case that it is difficult to use ESR, HPLC and other measurement methods, spectrophotometric determination of Ho· is considered to be a simple and practical method. Since HO· itself cannot be detected by spectrophotometry, it is necessary to select a suitable compound to react with HO· and generate UV-Vis light.

Characteristic absorption products can be produced in the area.

4. Fluorescence analysis.

Hydroxyl radical (..)OH) is one of the most active molecules and one of the most aggressive chemicals, which can undergo a variety of different types of chemical reactions with almost all biomolecules, organic or inorganic, and is accompanied by a very high reaction rate constant and electrophilicity of negative charge. Hydroxyl radical is the most toxic and harmful free radical in the reactive oxygen species that is currently known to be the most toxic and harmful to living organisms, which can interact with a variety of molecules in living organisms through electron transfer, addition and dehydrogenation, etc., resulting in oxidative damage of sugars, amino acids, proteins, nucleic acids and lipids, so that cell necrosis or mutation, hydroxyl radicals are also related to aging, tumors, radiation damage and cell phagocytosis.

Due to its short lifespan, high reactivity, and low concentration, hydroxyl radicals are not yet specialized.

First, the effective method can accurately determine the content of hydroxyl radicals, and its determination method has also become an international problem. In this paper, the hydroxyl radical detection methods that have emerged in recent years are reviewed.

1. Electron spin resonance method.

Electron spin resonance or electron paramagnetic resonance (EMR) mainly focuses on unpaired free radicals or transition metal ions and their compounds. The emergence of spin trapping technology has opened up a new way to detect free radical intermediates in chemical reactions and short-lived free radicals during life activities [[1]]. In this method, the scavenger is combined with free radicals to form relatively stable spin adducts, and then the ESR is measured.

2HPLC method.

HPLC can be used for indirect determination of free radicals. During the determination process, it is necessary to select the appropriate compound to capture the free radicals in the tested system to generate a product with certain stability that can be separated and detected by liquid chromatography, and then determined by HPLC. 1) HPLC detection of hydroxyl radical trapping by dimethyl sulfoxide.

2) HPLC determination method of hydroxyl radical trapping by salicylic acid.

3. Chemiluminescence method.

Chemiluminescence method is a sensitive and accurate method for detecting free radicals, and its principle is to use the luminescent agent to be oxidized into an excited state by reactive oxygen species radicals, and when it returns to the ground state, a large number of photons are released, thereby amplifying the luminescence. And the more free radicals are produced, the greater the luminescence value. The amount of free radicals in the indirect reaction system is calculated by function conversion.

Compared with ESR and HPLC, it has the advantages of easy operation, lower equipment cost, and rapid measurement.

4. Oxidation and fading photometry.

6. Polarography. 7. Capillary electrophoresis-electrochemical detection method.

8 micelle electrocapillary chromatography.

Hydroxyl radical (..)OH) is an important reactive oxygen species that is formed by the loss of an electron by hydroxide (OH-) in its molecular formula. Hydroxyl radicals have a very strong electron-gaining ability, that is, oxidation ability, oxidation potential. It is the second largest oxidant in nature after fluorine.

Hydroxyl radical (·OH) is a kind of reactive oxygen species of the Luming group. Hydroxyl radicals can kill red blood cells, degrade DNA, cell membranes and polysaccharified locust compounds, and many of the harmful effects caused by it have been found to be significantly reduced when hydroxyl radical scavengers are added.