Hyphenated techniques in anticancer drug monitoring: II. Liquid chromatography–mass spectrometry and capillary electrophoresis–mass spectrometry

High-performance liquid chromatography has become the separation technique of choice for the monitoring of generally thermolabile anticancer agents. With the introduction of electrospray mass spectrometry, the coupling of liquid chromatography and mass spectrometry has opened the way to widely and routinely applied anticancer drug monitoring. Real-time metabolism versus degradation can now be distinguished, since derivatization is no longer obligatory. This is important for the monitoring of the anabolic and catabolic pathways of the same agent, such as 5-fluorouracil. Detection limits almost equal to those obtained with capillary gas chromatography–mass spectrometry are realistic with the latest generation of mass spectrometers, enabling quantitative analysis of various anticancer agents and their metabolites down to the low ng/ml level. Furthermore, sample clean-up and chromatography can be downscaled markedly using the latest column technologies, such as the generally applied 10 cm×2.8 mm I.D. RP 18 columns. The coupling of capillary electrophoresis to mass spectrometry is today far from a routine application in anticancer drug monitoring. Nevertheless, interesting applications have been reported and are selected for the present review.