The principle of selecting the SPE cartridges specification is to first ensure that the SPE cartridges packing has sufficient capacity to retain the target compound 100% on the column. On the other hand, the filler is not too much. The more filler, the greater the amount of solvent that is effective for the target compound to elute.
Therefore, when selecting the specifications of the SPE cartridges, the SPE cartridges capacity must be considered. Cartridges capacity refers to the mass of a compound that retains a compound with a primary force per unit mass. The capacity of the bonded silica cartridges is generally from 1% to 5%. Take the SPE cartridges with 100 mg filler as an example, its larger capacity generally does not exceed 5 mg. The cartridges capacity of the ion exchanger is about 0.5 to 1.5 meq/g.
It is worth pointing out that because we are mostly a mixture, there are many interfering substances besides the target compound. Therefore, when selecting the size of the cartridges, it is necessary to consider the target compound and the total amount of interference substances that may be adsorbed under the extraction conditions, and not only the target compound.
Otherwise, even if the target compound does not exceed the capacity of the cartridge, the SPE cartridges retain some of the interfering substances while retaining the target compound. Since the total amount of the two has exceeded the capacity of the cartridge, the result is that some of the target compounds cannot be retained. On the SPE cartridges. Therefore, for the sake of safety, it is recommended that the capacity of the cartridge be better than twice the estimated target compound content.
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