Parallel ultra-high flow rate liquid chromatography with mass spectrometric detection using a multiplex electrospray source for direct, sensitive determination of pharmaceuticals in plasma at extremely high throughput

Recent years have seen increasing usage of large particle size stationary p hases and ultra-high flow rate liquid chromatography/mass spectrometry (LC/ MS) for rapid determination of pharmaceuticals in plasma without prior samp le preparation. This lack of sample preparation prior to analysis, together with the extremely high throughput of the chromatography, makes the techni que extremely attractive to the bioanalyst. Further, the introduction of mu ltiple 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 mu ltiple sprayer interface to the mass spectrometer. We have applied this on both the narrow-bore and capillary scale. This technique enables the quanti fication of drugs from four plasma samples simultaneously, at nanogram per millilitre concentrations, from small aliquots of plasma without sample pre paration and with throughputs of up to 120 samples per hour. Copyright (C) 2000 John Wiley & Sons, Ltd.