The use of turbulent flow chromatography coupled to mass spectrometry (turbulent flow LC/MS) shows great potential for the rapid, direct analysis of pharmaceutical compounds in plasma and serum. The use of turbulent flow LC/MS has removed the need for any time-consuming sample preparation such as solid phase extraction, and allowed a total sample analysis time of approximately 2.5 min to be achieved. The coupling of a mass spectrometer with HPLC often not only results in greater sensitivity, but also the added specificity of the mass spectrometer reduces the need for complete resolution of the analyte from endogenous material in the matrix. This allows an on-line analysis approach to be used for the analysis of pharmaceuticals in biological matrices. Turbulent flow chromatography is achieved by the use of high flow rates and large particle size stationary phases. When coupled with mass spectrometric detection, the technique allows the direct analysis of plasma or serum samples with very rapid chromatography and, therefore, extremely high throughout. This work demonstrates the suitability of this technique for the validated analysis of biological samples for a novel isoquinoline pharmaceutical and offers some ideas on the future continued development, optimization and application of turbulent flow liquid chromatography.

A liquid chromatography tandem mass spectrometry (LC/MS/MS) method has been developed for the fast routine analysis of selected CYP450 probe substrate metabolites in microsomal incubations, with no sample pretreatment. This has allowed fast and simple assessment of the potential effects which drug candidates may or may not have on the metabolism of specific CYP450 probe substrates, providing information which can then be used to rationalize in vivo interaction studies required in the clinic. This methodology takes advantage of fast gradient chromatography as a generic means of sample separation and analysis. It provides high throughput analysis compared to conventional gradient HPLC, with no significant loss in chromatographic performance.

Recent years have seen increasing usage of large particle size stationary phases and ultra‐high flow rate liquid chromatography/mass spectrometry (LC/MS) for rapid determination of pharmaceuticals in plasma without prior sample preparation. This lack of sample preparation prior to analysis, together with the extremely high throughput of the chromatography, makes the technique extremely attractive to the bioanalyst. Further, the introduction of multiple sprayer interfaces to mass spectrometers provides the potential for even higher throughput. In this paper, we present parallel ultra‐high flow rate liquid chromatography using four columns in parallel and a four‐way multiple sprayer interface to the mass spectrometer. We have applied this on both the narrow‐bore and capillary scale. This technique enables the quantification of drugs from four plasma samples simultaneously, at nanogram per millilitre concentrations, from small aliquots of plasma without sample preparation and with throughputs of up to 120 samples per hour. Copyright © 2000 John Wiley & Sons, Ltd.

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Monolithic columns have been successfully used with steep gradient and high flow rates for the direct analysis of a candidate pharmaceutical compound in human plasma. The monolithic columns showed excellent robustness with nearly 300 20-microL injections of plasma (diluted 1:1 with water) being made onto one column without significant deterioration in performance. The system gave excellent sensitivity with a limit of quantification of 5 ng/mL being achieved. Unlike previous methods of direct analysis the monolithic columns showed excellent resolution even after nearly 300 plasma injections. The column performance was measured before and after the analysis of the plasma samples.