3. SPE Approaches

The most common approach is the bind-elute format: after loading the sample onto a conditioned sorbent, the analytes of
interest are retained (bound) while many matrix components pass through. After a wash step to remove interferences, a
strong solvent is used to elute the analytes in a small volume.
An alternative is pass-through (flow-through) SPE, where matrix interferences are retained and the analytes are collected in
the effluent.