After selecting the type of SPE cartridges, we have to determine the specifications of the SPE cartridge.
The principle of selecting the SPE cartridge specification is to first ensure that the SPE cartridge 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, the SPE cartridge capacity must be considered when selecting the specifications for the SPE cartridge. Cartridge 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 cartridge is generally from 1% to 5%.
Take the SPE cartridges with 100 mg filler as an example. The maximum capacity is generally less than 5 mg. The cartridge 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 cartridge size, 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 cartridge capacity, the SPE cartridges retains some of the interfering substances while retaining the target compound.
Since the total amount of the two has exceeded the cartridge capacity, the result is that some of the target compounds cannot be retained. On the SPE cartridge. Therefore, for safety reasons, it is recommended that the cartridge capacity be better than twice the estimated target compound content.
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