Column-switching procedures for the fast analysis of drugs in biologic samples

Liquid chromatography coupled with mass spectrometry in single and dual mode (LC-MS and LC-MS/MS) is the method of choice for the quantification of drugs and their metabolites in biologic fluids. Following the new challenges encountered in the process of drug development, liquid chromatography-mass spectrometry has been found to achieve high-throughput analysis. With this impressive tool, the sample preparation step before analysis is simplified, and the analytic process speeded up. Several generic approaches have recently been developed for the sample extraction coupled on line with a LC-MS system. In this paper, different extraction supports allowing the direct injection of biologic fluids were investigated, namely, restricted-access media, large-size particle, and monolithic phases. In the column-switching configuration, these supports, coupled with microbore analytic columns, were found suitable for the fast analysis (total analysis time of less than 10 minutes) of different drugs and their metabolites in biologic matrices at the nanogram per milliliter level.