When selecting an appropriate cleaning solution, consider the types of contamination that will have deposited onto the capillary from the most recent fluid sampled. For instance, if DI water was sampled last, bacteria, or particles are the most likely sources of contamination. If solvents were sampled last, optical hazing due to chemical impurities is most likely. Both of these situations can be easily remedied using high quality laboratory glassware cleaner such as IsoClean® or Micro-90®. A 5% solution of glassware cleaner in ultra-pure DI water should be used.
In cases where polymers were sampled, the most likely cause of contamination is trace polymer dried to the capillary. In this case, long term soaking in the appropriate solvent for the polymer will probably be necessary to facilitate removal of the contaminant. Using the solvent with the cleaning syringes after soaking (assuming compatibility) should dislodge the residual contamination. Follow this with a DI flush, and, if necessary, additional cleaning with glassware cleaner.
Check out the two upcoming LiQuilaz Cleaning Procedures for application of this information. To read the full paper, click here.