Mass spectrometry-based bioanalytical methods

Mass spectrometry-based bioanalytical methods play an important role in the entire process of searching new medicines to improve the quality of human life. High-performance liquid chromatography coupled to a tandem mass spectrometer (HPLC-MS/MS) has become the standard tool for the determination of pharmaceuticals in various in vitro and in vivo samples stemming from drug discovery and development experiments [1-5], However, the major disadvantage of the HPLC-MS/ MS technique is that it does not readily provide information on the distribution of the administrated drug and its metabolites. 

Mazzarino, M., Thri, S., and Botre, F. (2008) A screening method for the detection of synthetic glucocorticosteroids in human urine by liquid chromatography-mass spectrometry based on class-characteristic fragmentation pathways. Analytical and Bioanalytical Chemistry, 390,1389-1402. 

Mass spectrometry (MS) has become one of the most important analytical tools employed in the analysis of pharmaceuticals. This can most likely be attributed to the availability of new instrumentation and ionization techniques that can be used to help solve difficult bioanalytical problems associated with this field (1-8). Perhaps the best illustration of this occurrence is the development of electrospray (ESI) and related atmospheric-pressure ionization (API) techniques, ion-spray (nebulizer-assisted API), turbo ionspray (thermally assisted API), and atmospheric pressure chemical ionization (APCI nebulization coupled with corona discharge), for use in drug disposition studies. The terms ESI and ionspray tend to be used interchangeably in the literature. For the purpose of this review, the term API will be used to describe both ESI and ionspray. In recent years there has been an unprecedented explosion in the use of instrumentation dedicated to API/MS (4,6,8-14). API-based ionization techniques have now become the method of choice for the analysis of pharmaceuticals and their metabolites. This has made thermospray (TSP), the predominant LC/MS technique during the 1980s, obsolete (15). Numerous reports describing the utility of API/MS for pharmaceutical analysis have appeared in the literature over the last decade (7). The... 

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