To Know Solid Phase Extraction Column Comprehensively

The solid phase extraction column is mainly used in sample pre-treatment of target compounds in various foods, agricultural and livestock products, environmental samples, and biological samples. There are many types of solid phase extraction columns. In specific experimental work, it is necessary to reasonably select suitable packing and reasonable specifications of solid phase extraction columns according to the analytical objects, detection methods, and laboratory conditions.

Principle of SPE column

SPE is a physical extraction process including liquid and solid phases; it can also be taken as a simple chromatographic process. The more commonly used method is to pass the liquid sample solution through the adsorbent to retain the tested substance, and then use a solvent of appropriate strength to wash away impurities, and then use a small amount of solvent to quickly elute the tested substance, so as to achieve the purpose of rapid separation, purification, and concentration.

C18A SPE Cartridges C8 SPE Columns

Specification of SPE column

The choice of solid phase extraction column is generally considered from two aspects: the choice of adsorbent and column specifications. The most commonly used one is made of polyethylene. The device is equipped with two plugs made of polypropylene or glass fiber, and a certain amount of chromatographic adsorbent is filled between the two plugs.

According to the volume of space above the classic packing, the specifications can be divided into 1 ml, 3 ml, 6 ml, 10 ml, 15 ml, 20 ml, 30 ml, 60 ml, and so on. There are also special specifications produced according to specific application requirements. From the outside, the classic one is similar to the injection syringe and is straight. The other is funnel-shaped at the top, which is convenient for loading more samples at one time during manual operation.

Packing of solid phase extraction column

Solid phase extraction packings are usually chromatographic adsorbents, which can be divided into three categories: the first type is based on silica gel (such as C18, C8, etc.); the second type is based on polymer, such as polystyrene-diethylene Benzene, etc.; the third category is based on inorganic materials, such as Flori diatomaceous earth, alumina, graphitized carbon and so on.

Capacity of solid phase extraction column

The capacity of the SPE column refers to the adsorption capacity of the filler. For the silica gel matrix, its capacity is generally 1~5 mg/100 mg, that is, the column capacity is 1%~5% of the mass of the packing. The capacity of the bonded silica gel ion exchange adsorbent filler is expressed in meq/g, that is, the capacity of each gram of packing is X milliequivalents and 0.5 to 1.5 meq/g is usually used.

When selecting, the column capacity must be considered. Because the sample matrices we face are usually more complicated, such as food, biological samples, and so on. The SPE adsorbent can adsorb the target compound, while it also absorbs impurities of the same nature. Therefore, considering the column capacity should be the target compound plus the total amount of impurities that can be adsorbed cannot exceed the column capacity. Otherwise, some target compounds may not be adsorbed during the sample loading process, resulting in a low recovery rate.