5. Sorbent Selectivity

The more complex the sample matrix, the more important it is to choose a sorbent with high selectivity. If the sorbent is insufficiently selective, matrix interferences can severely compromise quantitation. To efficiently separate and purify target analytes from high-matrix samples, understand the selectivity differences among reversed-phase, ion-exchange, normalphase, and mixed-mode sorbents.

If the target analyte is ionizable in water (exists as an ion), starting with a mixed-mode or ion-exchange sorbent rather than a non-selective hydrophobic sorbent will better suppress matrix effects and yield a cleaner extract.