Application of Solid Phase Extraction Technology in Environmental Analysis
( 1 ) Application of solid phase extraction technology in water analysis   Drinking water, groundwater and sewage can be used directly for solid phase extraction as long as they do not contain large amounts of solid particles. Groundwater and sewage may require filtration before using solid phase extraction. If the compound of interest is bound to the discarded particles, filtration will reduce its recovery. If it is possible to filter the sample as much as possible, let the unfiltered sample pass directly through the SPE, and let the solvent pass through the particles above the adsorbent during the elution process. This will increase the recovery because in this way the compound of interest bound to the particles will be recovered. In most cases, the water sample is subjected to reverse phase or ion exchange solid phase extraction.  The determination of pesticide residues in water is generally carried out using non-polar adsorbents such as C18 and C8 , usually conditioned with methanol and water, and methanol as the eluent . Since the pesticide residues in water by demanding, natural water the residual concentration of the pesticide is usually very low, if there is no reliable means for separation and enrichment difficult to detect, using solid phase extraction technique enables extraction, purification and enrichment Complete in one step . The large volume sample is pre-concentrated by solid phase extraction column , eluted with a small volume of eluent , and then concentrated and measured for concentration , which greatly reduces the detection limit of the detection method . ( 2 ) enrichment of trace organic compounds in ambient air Volatile and semi-volatile substances in environmental air pollutants account for 90% , and the rest are granular pollutants ; granular pollutants can be trapped by membranes , and solid phase extraction ( solid adsorption ) for volatile and semi-volatile is generally used . Solution absorption and cryogenic condensation enrichment sampling. Solid phase extraction enriches the organic matter in the ambient air by packing a uniform phase of a uniform particle size into small columns , passing air through the small column at normal temperature or low temperature , due to the different partition coefficients of the organic compounds between the gas phase ( air ) and the stationary phase. the trapped compounds to be retained in a small column, the normal air components such as nitrogen, oxygen flows through the cartridge, the purpose of enriched organic compounds. ( 3 ) Application of solid phase extraction technology in the analysis of pesticide residues in soil The determination of pesticide residues in the soil is generally carried out by extracting the pesticide to be tested from the soil sample with an appropriate extraction solvent and extraction method , and then purifying it by solid phase extraction . The nature of the pesticide to be tested is different , and the nature of the impurities brought from the matrix is ​​not the same . Therefore, the appropriate adsorbent should be selected to separate and purify the pesticide to be tested . Analysis polar pesticides, extraction using polar solvents such as acetone - water system, may be employed and other non-polar adsorbents such as C18, extraction solvent so strong water-soluble impurities not retained on the adsorbent , facilitate purification of the sample; less polar pesticides analysis, when using the less polar extraction solvent may be selected as an adsorbent Florisil like polarity, it will not retain the extraction solvent is less polar impurities, Then, the residual pesticide to be tested is rinsed down by selecting an appropriate solvent for measurement. Infrared Vein Finder,High Quality Infrared Vein Finder,Infrared Vein Finder Details, CN Wuxi Biomedical Technology Co.,Ltd , https://www.wxbiomedical.com