SPE solid phase extraction equipment technology is a sample pretreatment method based on chromatographic theory. It uses selective adsorption and selective elution to enrich, separate and purify samples. Compared with traditional liquid-liquid extraction, solid-phase extraction has the advantages of strong selectivity, short separation time, high recovery rate, difficult emulsification, less organic solvent consumption and easy automation, etc., and is widely used in water quality testing, pharmaceuticals, and environmental analysis, food analysis and tobacco analysis and other fields.
SPE solid phase extraction is to use solid adsorbent to absorb the target substance in the liquid sample, so that the target substance is separated from the sample matrix and interfering compounds, and then eluted with eluent or heated medium for adsorption, so as to achieve the purpose of separation and enrichment of the target substance. SPE solid phase extraction does not require a large amount of immiscible solvents, and there will be no emulsification during the process; due to the use of highly selective adsorbents (stationary phases), solid phase extraction can significantly reduce the amount of solvents. The pretreatment process of solid phase extraction is simple and low cost.
At present, the commonly used adsorbents include positive and reversed phase adsorbents, ion exchange adsorbents and antibody-bonded adsorbents, etc. During the test, try to choose an adsorbent with a polarity similar to the target compound, and the dosage is related to the properties of the target compound (polarity, Volatility) and its concentration in the water sample are directly related.
In SPE solid phase extraction, the choice of elution solvent is related to the properties of the target substance and the adsorbent used. You should refer to the polarity and elution strength of common organic solvents. Choose. The volume of the eluent should be based on the premise that the elution is complete, and the smallest volume is the best. The optimal eluent volume can be found according to the change curve of the recovery rate through the multiple elution method (small volume). Obviously, the smaller the elution volume, the higher the enrichment factor.
During sample addition, retention volume is one of the key factors in SPE solid phase extraction techniques. It represents the volume of water sample that can be effectively processed for trace enrichment. According to the minimum detection amount of the chromatographic analyzer and the concentration of organic matter in the water sample, the minimum volume of the water sample to be enriched can be estimated. In addition, the pH value of the sample liquid also affects the adsorption efficiency of the SPE solid phase extraction sample.
The control of the flow rate is very important to the solid phase extraction. If the flow rate is too high, the solid phase extraction column will leak. If the flow rate is too small, the processing speed will be too slow. During the column pretreatment process, the flow rate is moderate, and it is enough to ensure that the solution is fully wetted to the adsorbent. During the sample loading and elution process, the flow rate is required to be as slow as possible, so that the analyte can be retained in the column as much as possible or completely eluted, otherwise, the analyte will be lost and the recovery rate will be affected. In particular, the ion exchange process is relatively slow, and a lower flow rate should be used.
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