Combining Dispersive Pipette XTRaction + SALLE (Salt Assisted Liquid-Liquid Extraction) for a novel cleanup mechanism

Method Overview

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

Customize this method based on your workflow!

Generic Workflow

1aBlood/Serum: Add I.S. + ACN
Protein Precipitate
Transfer Supernatant and add FA aqueous
1bUrine/ Oral Fluid/ Other: Add I.S. + ACN + FA aqueous
2Aspirate/Dispense sample solution
Transfer acetonitrile (upper) layer
3Inject, dilute or solvent evaporate
Injection volume can vary or can include a specific concentration/ dilution factor


  • Automation friendly pipette tips eliminate need for offline liquid-liquid extraction
  • This methodology works with a variety of biological matrices including: serum, blood, urine or saliva
  • Amount of sorbent + salt customizable
  • Workflow flexibility
  • Minimize required matrix volume
  • Provides sensitive quantitation and simplifies sample preparation
  • Rapid extraction process – aspirate/dispense steps take seconds!

Clinical & Forensic Applications

MatrixTarget AnalyteProductsMatrix VolumeSolvent EvaporationAutomationDocuments
UrineTHC & MetabolitesXTR tips: 20 mg WAX + 40 mg Salt200 µLNo< 5 minutesSimultaneous quantification of 11 cannabinoids and metabolites in human urine by liquid chromatography tandem mass spectrometry using WAX-S tips
Whole BloodTHC & MetabolitesXTR tips: 10 mg WAX + 20 mg Salt100 µLNo< 2 minutesQuantification of cannabinoids and their free and glucuronide metabolites in whole blood
SerumVitamin DToT Filtration for protein precipitation + WAX-S XTR tips75 µLNo< 5 minutesAutomated Vitamin D Extraction from Serum
Urine/ SalivaCortisolXTR tips: 10 mg WAX + 40 mg Salt100 µLNoThe application note follows a manual protocol but we can provide automation support for this method.Rapid Sample Preparation for Quantitation of Cortisol from Saliva and Urine

Learn more about XTR tips

Need Custom Method Development?

Our team of application scientists can help you integrate DPX products seamlessly into your workflow. Or we can help you develop new methods!