The Important Role-SPE Cartridge in SPE

SPE is a separation principle using liquid chromatography using selective adsorption and selective elution. The more common method is to pass the liquid sample solution through the adsorbent, retain the substance to be tested, and then use the appropriate strength solvent to wash away the impurities, and then quickly elute the test substance with a small amount of solvent, thereby achieving the purpose of rapid separation, purification and concentration.

It is also possible to selectively adsorb the interfering impurities and let the measured substance flow out; or simultaneously adsorb the impurities and the tested substance, and then selectively elute the test substance with a suitable solvent.

The total mass of the analyte and the interferent adsorbed by the adsorbent in the cartridge should not exceed the adsorbate, 5% of the total mass. The volume of the eluent should generally be 2-5 times the volume of the cartridge of the extraction cartridge.

Interaction of SPE Cartridge
The force in the solid-phase extraction process is divided into several parts, including non-polar interaction, polar interaction, iron interaction, and secondary interaction. Non-polar extraction is suitable for the separation of compounds with different structures, and can keep compounds with non-polar genes on absorbents containing non-polar functional groups; polar interaction contains hydrogen bonding, dipole, induced dipole and other interactions, polar interaction has obvious effect in non-polar solvents when the primary polar has interacted with silica gel bonded absorbents; iron interaction is good for enhancing retention of targeted compounds and promotion of elution process.

SPE cartridge
1.Packing
Solid-phase extraction packing is usually chromatographic adsorbents and can be divided into three major categories: the first is based on silica gel (eg C18, C8, etc.); the second is based on high polymers, such as polystyrene – two Ethylene benzene, etc.; the third type is mainly inorganic materials, such as Floris diatomaceous earth, alumina, graphitized carbon, and the like.

2.Volume
Cartridge capacity must be considered when selecting an SPE cartridge. Because the sample matrix we are facing is usually more complex, such as food, biological samples and so on. In solid-phase extraction, the solid phase extraction adsorbent adsorbs the target compound and adsorbs impurities of the same nature. Therefore, considering the cartridge capacity, it should be that the target compound plus the total amount of impurities that can be adsorbed cannot exceed the cartridge capacity. Otherwise, some of the target compounds may not be adsorbed during the loading process, resulting in a low recovery rate.

3.How to use
The simplest solid phase extraction can be done manually, by attaching a syringe to the upper end of the SPE and extruding the liquid from the extraction cartridge out of the extraction column by squeezing the syringe. Alternatively, a batch sample may be subjected to a solid-phase extraction operation using a positive pressure or negative pressure solid phase extraction apparatus. With the development of technology and the increase in the number of samples, more and more analytical laboratories began to use automated solid-phase extraction, especially multi-channel solid-phase extraction to process batch samples.