Depending on the analytes you use with the Column, there are a number of strategies you can try:
• If your HPLC pump and system has more than two solvents, you could include a third line with a cleaning solvent. Then in the injection sequence you could insert a wash step which uses only the third solvent. The nature of the samples will dictate how frequently you need to do a washing. For serum samples, we recommend about every ten injections or fewer.
• Using a guard column can be an effective technique because strongly adsorbed contaminants will build up at the front of the column. Therefore if you have a guard column attached, these compounds will build up here instead of on the analytical column. You can then replace these guard cartridges as needed.
• You can also backflush the analytical column. If the column is facing the other direction, the contaminants will come off more easily with the proper wash solvents. We often recommend using 50:50 MeOH / Water or 50:50 IPA / Water.
The advantage of using Cogent™ columns over those based on standard “type B” silica is that they more likely can be readily cleaned and restored to initial conditions. The reason is because of surface differences between the two materials. Cogent™ columns are based on TYPE-C Silica™, which is more hydrophobic and has virtually no silanols. Contaminants can therefore be more readily washed from the column. In contrast, contaminants may be more strongly adsorbed onto type B columns due to the more active surface sites on this material.