Solid-phase extraction(SPE) has the same fundamental basis as HPLC. When you have knowledge of the chromatographic behavior of the analytes of interest,you can choose the proper sorbent and eluents. That means if you know the certain chromatographic conditions can provide good separation of your analyte from interference, a similar SPE sorbent and solvent combination might be your choice. If you try to remove an interference with solutes in HPLC, you will find out that similar SPE conditions won’t work very well.
Generally,there are two ways to isolate and clean up sample components of interest: one is to adsorb matrix interference as while as components of interest pass through the cartridge unretained, the other one is to adsorb components of interest, and the matrix interference pass through the cartridge without any retaining at the same time.
You can choose the first way when the desired sample component is present in high concentration. And the second way can be the choice When you find the components of interest are presenting at low levels, or when you need to isolate the multiple components of different polarities.
Fillers used for SPE cartridges are usually chromatographic adsorbents, which can be divided into three kinds: the first is based on silica gel such as C18、C8, etc.; the second is based on polymers such as polystyrene-divinobenzene, etc.; and the third is based on inorganic materials such as verori diatomite, alumina, graphitic carbon, etc. different kinds of fillers can meet different needs of your applications.
Constituent Elements of SPE Cartridge SPE cartridge is composed of medical PP empty tube, medical PE sieve plate, and a fixed adsorbent. PE made tube has high chemical compatibility and wonderful reproducibility. Medical PE sieve plate has average pore size and good flow rate. It can be used to retention or elution of polar and halogenated compounds in a pollution-free way.
Silica Gel Type SPE Cartridge Most of the SPE cartridges are silica gel type made of polyethylene, which contain two pieces of plug made of polypropylene or glass fiber, and a certain amount of chromatographic adsorbent is filled in the middle of the two pieces. The upper end of the solid phase extraction column is open, the lower end is the outlet, and the liquid is discharged from the outlet after passing through the adsorbent. According to the space volume above the packing of the classical solid phase extraction column, the specification of the solid phase extraction column can be divided into 3mL、6mL、12mL and so on.
Polymer and Adsorption Type SPE Cartridge There are also SPE cartridges of special specifications produced according to multiple of quality sorbent choices. The polymer type SPE cartridge is a universal sorbent which can meet all different SPE needed occasions. From the appearance of the solid phase extraction column, the polymer and adsorption type extraction column is similar to the injection syringe and is straight cylinder type, which is convenient to load more samples at one time during manual operation.