Solid phase extraction Solid phase extraction (SPE) is a sample pretreatment technology composed of column chromatography separation process, separation mechanism, stationary phase, and solvent selection, etc. Solid phase extraction cartridge is developed by combining liquid-solid extraction and liquid chromatography technology. There are many similarities with high-performance liquid chromatography.
However, the particle size of SPE cartridges packing material (>40μm) is larger than that of HPLC packing material (3~10μm). The difference between SPE cartridges chromatography and HPLC chromatography is that the column is low, the number of plates is small, the separation efficiency is low, and it is used for one time, which can separate and retain compounds with very different properties.
Because SPE realizes the trinity process of selective extraction, separation, and concentration, with short operation time, small sample size, and few interfering substances, it can be used for the analysis of volatile and non-volatile substances and has good reproducibility.
With the help of SPE, it can be achieved: remove substances that interfere with subsequent analysis from the sample; enrich trace components to improve analysis sensitivity; change the sample solvent to match the analysis method; in-situ derivatization; sample desalination; storage and transportation of samples.
As the preferred method for preparing liquid samples, SPE replaces the traditional liquid-liquid extraction method. Therefore, since the emergence of SPE, it has been expanding its application at an annual growth rate of 10%.
Features of SPE cartridge
Compared with LLE (liquid-liquid extraction), the SPE cartridges , an effective method for sample purification and enrichment before analysis and determination, has the characteristics of less organic solvent consumption, convenience, safety, high efficiency, and low cost.
The advantages of relatively high analyte recovery rate and good reproducibility of analysis results are widely used in the fields of food, medicine, environmental protection, disease control, and hygiene, commodity inspection, and pesticide residue analysis. In the chromatographic analysis, sample purification can also extend the service life of the chromatographic column; The enrichment and concentration function of SPE sample preparation for the target analyte can improve the analytical method’s detection sensitivity greatly.
SPE is essentially a liquid chromatographic separation, and the adsorbent used is also the same as the liquid chromatographic stationary phase but differs in particle size. The general practice of SPE solid phase extraction cartridges is: using the principle of selective adsorption and selective elution chromatography, the liquid sample is passed through the adsorbent, the analyte is retained, the impurities are washed out with a solvent of appropriate strength, and then washed with a small amount of solvent.
The analyte is removed to achieve the purpose of rapid separation, purification, and concentration. There is also a practice of selectively adsorbing interfering impurities and allowing the analyte to be washed away, or adsorbing both the impurities and the analyte, and selectively eluting the analyte with a suitable solvent.