Application of microwave extraction equipment in various industries

- May 07, 2019 -

Microwave equipment has extraction function. The special advantages of microwave extraction technology make it a powerful tool for sample extraction. It has been applied to extract polycyclic aromatic hydrocarbons (PAHs), pesticide residues, oils, aromatic oils, trace elements and their compounds, organic metal compounds and plants from soil, food, meat, vegetable, oil, eggs, dairy products, sediments and other samples. Extraction of ingredients, harmful substances, mycotoxins, metals in minerals and pesticide residues in serum and biological samples. According to the application of microwave extraction in different fields, the following categories are classified: microwave extraction of organic pollutants

1, microwave extraction of organic pollutants

P>soil, River mud, marine sediments, environmental dust and organic pollutants in water generally refer to polymers, polycyclic aromatic hydrocarbons, chlorides, benzene, herbicides, lubricants and phenols. The advantage of microwave extraction of organic pollutants in different substrates is that only one tenth of the solvent in conventional extraction method is needed, and the extraction time is about 5-20 minutes. Polycyclic aromatic hydrocarbons (PAHs), phenolic compounds, organic pollutants in river mud, marine sediments, environmental dust, polychlorinated biphenyls (PCBs) and other organic pollutants in water were applied to soil samples. Alkanes in soil, polycyclic aromatic hydrocarbons and herbicides, water, sediments and polycyclic aromatic hydrocarbons in biological tissues have been used in this way. The content of pesticide residues extracted by microwave equipment is very low (ppm-ppt). In fact, the sensitivity of the analytical method is improved by using less extraction solvent (about 1/10) to extract the same amount of pesticide residues by microwave extraction. However, microwave extraction of pesticide residues in different matrices requires different extraction solvents from conventional methods, so that the solvents can not only absorb microwave energy better, but also effectively extract pesticide residues from samples. The results showed that the microwave-assisted extraction could obtain the same recovery rate of organochlorine pesticide residues as Soxhlet extraction in 6 hours with isooctane, n-hexane/acetone, benzene/acetone (2;1), methanol/acetic acid, methanol/n-hexane and isooctane/acetonitrile as solvents under certain humidity in soil or sediment. The recovery rates of 12 kinds of agricultural residues (aldrin, alpha-hexahexahexane, beta-hexahexahexane, 4,4'-DDT, dieldrin, endosulfan I, endosulfan II, isodieldrin, heptachlorine, heptachlorobenzene, heptachlorocyclopentadiene) extracted from soil by microwave were compared with those by conventional EPA method. The results showed that the recovery rate and precision of microwave extraction for 10 minutes were better than those of Soxhlet method prescribed by EPA. Other samples of pesticide residues extracted by microwave method include meat, eggs and dairy products, dust, water and sediment from soil, sand and vacuum cleaner, lard, vegetables (beet, cucumber, lettuce, chili and tomato), garlic and onion.

3. Microwave extraction of metals and their compounds

P>Soil, River mud, sediment and some plant samples of marine biology river, heavy metal elements and toxic elements (such as tin, mercury, lead, zinc, arsenic, antimony, etc.) are all items that need to be detected frequently. Microwave extraction enriches and separates these elements or their compounds, which not only consumes less reagents, makes samples quickly, but also has high detection sensitivity. The main factors affecting microwave extraction of metals and their compounds in different matrices are extraction temperature, acid content in solvent, extraction time and solvent (toluene) content. Microwave assisted extraction of metal elements or their compounds from soil, marine sediments, minerals and slag, and then determination by emission spectroscopy or mass spectrometry with satisfactory results. Four different solvents, isooctane, methanol, deionized water and artificial seawater, were used to investigate the stability and extraction recovery of butyl and phenyltin derivatives under different microwave powers, such as BuSnCl3 (MBT), Bu2SnCl2 (DBT), Bu3SnCl (TBT), PhSnCl3 (MPT), Ph2SnCl2 (DPT), PSnCl (TPT) and Ph2SnCl (TP2T) in sediments. The results show that microwave assisted extraction of organometallic compounds from complex matrices is not only feasible and inexpensive, but also can significantly reduce the time required for the whole analysis and testing to about 20-2% of the original. Microwave extraction of elements in different matrices was studied. Methyl mercury and arsenic in marine organisms, copper, magnesium, zinc and lead in biological and plant samples, organic arsenic in river mud, heavy metal elements in organotin River (Cu, Cr, Ni, Pb and Zn), mercury, lead, zinc and copper in soil, arsenic and selenium in coal.

4. The clinical application of microwave extraction

In clinic, some drugs (sedatives) in human blood or serum, such as Lidocaine, Methadone, Diazepam, Nordiazepan, Propoxyphene, Morpropoxyphene, etc. were selectively extracted by microwave. This extraction method has been successfully used to detect several cases. The microwave extraction method for isolating antibodies from the surface of red blood cells only takes 10 minutes, while the conventional method takes 60-90 minutes. Microwave extraction has also been used to isolate antigens from plasma and serum. Extraction of active components from plants by microwave equipment is an important part of chemical research. Microwave extraction also shows its unique advantages. It has been reported in the literature that rosemary and menthol contain rosemary or menthol oil mixture, pyrrole dialkyl alkaloids in vegetable plants, and different plants. Extraction of pyrimidine glycosides, gossypol and alkaloids, extraction of vitamin B from grain and milk, fragrance and fragrance of plants, and extraction of Paris polyphenols from traditional Chinese medicine. These studies show that the distinct advantage of microwave method is to significantly reduce extraction time and solvent consumption. Rapeseed, olive seed and grape seed treated by microwave can increase the yield of oil. This set of equipment for accelerating and improving the yield of vegetable oil by microwave has been produced and sold by a Canadian company. Studies on the effects of microwave radiation and gamma rays on the extraction of unsaturated components from flavors and fragrances showed that the unsaturated components in nine flavors and fragrances were not affected by microwave radiation for 20 minutes in 2450MHz, but the gamma rays of 5 or 10KGY (a unit of radiation measurement) broke the unsaturated components in flavors and fragrances.

6. Other applications of microwave extraction

In addition to the application in several main aspects mentioned above, microwave equipment extraction has also been used for the extraction and separation of mycotoxins, fatty acids and harmful substances in mushrooms, soil, natural and man-made contaminated cereals. Microwave-assisted extraction was also used to extract aromatic oils and free amino acids in food, thiamethazine in pork, chloramphenicol residues in egg yolk and protein, accelerated coagulants in rubber formulations, stabilizers and additives in polyolefins, and C60 and C70 in fullerene fumes.

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