Method And Principle Of Solid Phase Extraction Column
Solid phase extraction column (spe) is a kind of sample pretreatment device developed from chromatography column for extraction, separation and concentration.Thermo chromatographic column and Waters chromatographic column are commonly used in the experiment.It is mainly used for the pretreatment of target compounds in various kinds of food, agricultural and livestock products, environmental samples and biological samples.
In order to separate and enrich the target compounds, the spe apparatus used solid adsorbents to adsorb the target compounds in the liquid sample, separated them from the matrix and interfering compounds in the spe column of sample c18, and then eluted them with elution solution or desorption by heating.
Compared with liquid-liquid extraction, spe has many advantages: spe does not need a large number of insoluble solvents, and does not produce emulsification in the treatment process. It USES highly selective adsorbent (fixed phase), which can significantly reduce the amount of solvent, simplify the sample processing, and reduce the cost.Generally speaking, the time of spe is 1/2 of that of liquid-liquid extraction and the cost is 1/5 of that of liquid-liquid extraction.The disadvantage is that the recovery and precision of the target compound are lower than that of liquid-liquid extraction.
The model and principle of solid phase extraction
Solid phase extraction is essentially a liquid chromatography separation, the main separation mode is the same as liquid chromatography, can be divided into positive phase (adsorbent polarity is greater than the polarity of the eluent), reverse phase (adsorbent polarity is less than the polarity of the eluent), ion exchange and adsorption.The adsorbents used in spe are also the same as the fixed phase commonly used in liquid chromatography, except that the particle size is different.
The adsorbents used in normal solid phase extraction are polar and are used to extract (retain) polar substances.Target when positive phase extraction using c18 solid phase extraction small column compound how to keep on the adsorbent, depend on the polar functional groups of target compounds and the interaction between polar functional groups on the surface of the adsorbent, including the hydrogen bond, PI, PI bond interaction, dipole-dipole interactions and dipole – induced dipole interaction and other polarity – polarity effect.Polar compounds can be adsorbed from non-polar solvent samples by positive solid phase extraction.
Usage of spe column:
The simplest spe can be done manually by attaching a syringe to the top of the spe column and squeezing the fluid out of the column.In addition, a positive or negative pressure spe device can be used to perform spe on bulk samples.With the development of science and technology and the increase of sample quantity, more and more analysis laboratories begin to use automatic spe, especially multi-channel spe to process batch samples.
Principle of spe column:
SPE technology is based on the theory of liquid-solid phase chromatography, which USES selective adsorption and elution to enrich, separate and purify samples. It is a physical extraction process involving liquid and solid phases.It can also be approximated as a simple chromatographic process.SPE is the separation principle of selective adsorption and selective elution by liquid chromatography.
The more common method is to make the liquid sample solution through the adsorbent, retain the measured substance, then choose the appropriate strength of solvents to wash away impurities, and then use a small amount of solvents to quickly elute the measured substance to achieve rapid separation purification and concentration of the purpose.It can also selectively absorb interfering impurities and cause the measured substance to flow out.Or adsorb both the impurity and the measured substance, eluting the measured substance selectively in an appropriate solvent.
General process for extraction column use:
Firstly, the sample was treated, the sample was activated on the extraction column, the processed sample was added slowly, the column was cleaned, a few times for elution, then the eluent was blow-dried with a nitrogen blower, the volume was redetermined, and the analysis was carried out on the machine.
At present, extraction column is applied in the field of food safety in China, such as the analysis of drug residues of various antibiotics and antimicrobial drugs in various kinds of food.Analysis of pesticide residues in agricultural and sideline products;Analysis of the amount of legal and illegal additives in many kinds of food.In the field of pharmaceutical research and analysis, the pharmacokinetic, pharmacokinetic data analysis and pharmaceutical composition analysis are widely used in drug research and development.Because it is easy to use and practical, it is more and more widely used.