Increased throughput in quantitative bioanalysis using parallel-column liquid chromatography with mass spectrometric detection

The feasibility of quantitative bioanalysis by parallel-column liquid chrom atography in conjunction with a conventional single-source electrospray mas s spectrometer has been investigated using plasma samples containing a drug and its three metabolites. Within a single chromatographic run time, sampl e injections were made alternately onto each of two analytical columns in p arallel at specified intervals, with a mass spectrometer data file opened a t every injection. Thus, the mass spectrometer collected data from two samp le injections into separate data files within a single chromatographic run time. Therefore, without sacrificing the chromatographic separation or the selected reaction monitoring (SRM) dwell time, the sample throughput was in creased by a factor of two. Comparing the method validation results obtaine d using the two-column system with those obtained using the corresponding c onventional single-column approach, the methods on the two systems were fou nd to be equivalent in terms of accuracy and precision. The parallel-column system is simple and can be implemented using existing laboratory equipmen t with no additional capital outlays. A parallel-column system configured i n this manner can be used not only for the within-a-run analysis of two sam ples containing two different sets of chemical entities, but also for the w ithin-a-run analysis of two samples containing the same set of chemical ent ities. Copyright (C) 2001 John Wiley & Sons, Ltd.