Hyphenated techniques in anticancer drug monitoring: I. Capillary gas chromatography–mass spectrometry

Most anticancer agents are relatively unstable substances and are subjected to intensive metabolism in vivo and degradation during sample pretreatment. Hyphenated techniques including a separation technique and, most frequently, mass spectrometry are therefore chosen to obtain insight into the in vivo behavior of anticancer agents. Once established, simpler assays can be derived from those based on hyphenation, which are less expensive. Capillary gas chromatography (cGC)–mass spectrometry (MS) is amongst the most frequently applied hyphenated analytical technologies in anticancer drug monitoring. Here a selection has been made of: (i) cGC–MS applied to the analysis of agents frequently used in clinical oncology (e.g. tamoxifen, oxazaphosphorines); (ii) cGC–MS applied to the development of new agents (Swainsonine and Brefeldin); (iii) cGC–MS applied to the analysis of agents for which comparisons with other frequently applied hyphenation technologies are possible (see Part I of this series). cGC–MS played a key role in the elucidation of the in vivo behavior of the oxazaphosphorine cyclophosphamide, historically the most frequently applied anticancer agent. cGC–MS appeared to be of special interest in the analysis of cyclophosphoramide and congeners in human erythrocytes by coupling of the hyphenated technique with a measurement of sediment technique. This resulted in the quantitative and qualitative analysis of oxazaphosphorine-related mustard gas moieties in human erythrocytes for the first time.