The Use of Secondary Ionic Interactions for the Solid-Phase Extraction of Some ‘β-Blocking’ Drugs on C-18 Bonded Silica

Abstract

A major advance in the preparation of biological samples for Chromatographic analysis was the introduction of SPE* [which featured strongly in Vol. 16, this series — Ed.]. This methodology involves adsorption of the analyte onto a solid phase (usually a modified silica gel, e.g. C-18 bonded) contained within a disposable cartridge. The compound of interest is then recovered by elution with a suitable solvent. We previously described some unusual and unexpected results obtained with C-18 bonded silica gel SPE cartridges, from two different manufacturers, used for extracting a number of ‘α-blocking’ drugs from plasma [1]. Here we describe further investigations on a wider range of commercially available C-18 cartridges.