XTR tips can house sorbents like weak anion exchange (WAX) or reverse phase (RP) for cleanup and the salt (S) necessary for SALLE. Example: WAX-S or RP-S tips.
- Salt dissolves in solution during aspirate/ dispense steps and acetonitrile separates due to increased ionic strength
- Solution can be analyzed directly, diluted or solvent evaporated and reconstituted in LC mobile phase depending on the workflow/application
- Ideal for applications that require acetonitrile for protein precipitation and are focused on hydrophobic analytes