XTR tips can house sorbents like weak anion exchange (WAX) or reverse phase (RP) for cleanup and the salt (S) necessary for SALLE. This methodology is ideal for applications that require acetonitrile for protein precipitation and are focused on hydrophobic analytes.
Aspirate and dispense steps mix sample solution with sorbent and salt. The salt dissolves in the solution and the acetonitrile separates due to the increased ionic strength of the solution. The upper acetonitrile layer is transferred to a clean vial. The solution from the upper layer can be analyzed directly or after dilution with water. Alternatively the solution can be solvent evaporated and reconstituted in LC mobile phase depending on the workflow for your application.
This methodology is another example of the unique customization available with XTR tips for INTip solid phase extraction. The amount of sorbent and salt in each tip can be scaled up or down depending on the sample volume.