Common Terminology for Solid Phase Extraction (part 3)
Equilibrium: Remove the activation solvent to create a suitable solvent environment for the sample. The solvent used is usually the same as the solvent of the sample solution. For the ion exchange column, if the sample is a basic compound, it is necessary to add acid if the sample is acidic. It is often necessary to add a base in the compound balance solution;
Retention: When the sample solution passes through the adsorbent, and the force of the adsorbent and certain compounds exceeds the force of the latter and the solvent, these compounds are fixed by the adsorbent, and the process is called retention;
Washing: After loading, some of the interferents are retained at the same time as the target compound. It is necessary to add a suitable solution to remove the interferences without affecting the retention of the target compound. Usually, the sample solvent is used for loading. Washing does not affect the recovery rate, but the solvent with higher elution intensity can remove the interference. When choosing the eluent, it is necessary to find a balance between the recovery rate and the purification effect;
Elution: Allows a solvent with a strong elution ability to pass through the adsorbent, interrupting the interaction between the adsorbent and the retained compound, allowing these compounds to flow out of the adsorbent with the solvent; usually, it is just right The elution solvent for eluting the target compound is selected, and at this time, less interferent is washed off, and a balance point between the recovery rate and the purification effect is also required when selecting the eluent;
Breakthrough: When the retention capacity of the adsorbent is weak or the mass of the compound exceeds the capacity of the adsorbent, some or all of the target compounds are not retained and flow out of the cartridge during the loading process; this phenomenon is an operational accident and should be avoided. occur.