Q1(c). Solid-phase extraction

Answer in brief

SPE transfers selected solutes from a liquid sample to a solid sorbent, followed by selective elution.

Key points

• Retention depends on differential adsorption, partition or ion-exchange affinity between sample components and the sorbent.
• Condition the cartridge, load the sample, wash away weakly retained matrix and elute the analyte with a stronger solvent or altered pH.
• It provides cleanup and preconcentration; the choice of sorbent and eluent controls recovery and selectivity.