Abstract
The traditional liquid-liquid extraction method for the removal of drug from biological matrix is being superseded by solid phase extraction. This involves the selection of an appropriate sorbent (normal-phase, reversed-phase, ion-exchange etc.), but once this has been achieved the method is quick and simple to operate. Most sample handling losses are avoided so recovery of drug is high and it is easily automated. Disposable columns have several advantages. Samples of 0.05-2.0 ml can be analysed routinely. Several wash stages can be included in a method to provide a specific extraction prior to a quick analysis by high-performance liquid chromatography (HPLC), radioimmunoassay, UV etc. A potential problem is that retention of the drug may involve more than one mechanism. Elution of drug may therefore require a stronger eluting solvent than analytical HPLC systems using the same stationary phase.
Collapse