Principles and Applications of LC-MS/MS for the Quantitative Bioanalysis of Analytes in Various Biological Samples

Standard technology for analyte detection in clinical chemistry fields rely on indirect characteristics of an analyte, e.g. its absorption capability of light, chemical reactivity or physicochemical interaction with macro-molecules as like antigen-antibody interaction. Otherwise, analytes are detected directly from molecular characteristics as molecular mass and molecular disintegration patterns in mass spectrometric method. Thus, mass spectrometric technology are very attractive for the quantification of biomarkers or chemicals in the context of diagnostic procedures since those techniques can be provide higher quality of analysis of much higher specificity compared to standard technologies such as photometry or ligand-binding tests. Even if gas chromatography-mass spectrometry (GC-MS) is first introduced mass spectrometric methods to laboratory medicine about 40 years ago and provide highly specific and sensitive quantification of thermo-stable molecules below a molecular weight of about 500, application of GC-MS method remained restricted to few specialized institution in laboratory medicine such as mainly toxicology laboratories, medical centres, and reference laboratories. The handling and maintenance of GC-MS instruments is very demanding and time-consuming; sample preparation is very laborious and includes procedures of sample extraction and analyte derivatisations and long run time with a typical sample throughput of less than 50 samples per day. Over the past decade with introduction of atmospheric pressure ionization (API) techniques, liquid chromatography-mass spectrometry (LC-MS) has undergone tremendous technological improvement allowing for its applications to endogenous components such as proteins, peptides, carbohydrates, DNA, and drugs or metabolites. Furthermore, powerful new technologies of ion-analyses (tandem MS, timeof-flight MS, ion-trap MS) substantially increased the capabilities of MS analyzers with respect to specificity and to the extent of data read out. These developments suggest a more widespread use of MS techniques superior to other analytical methods in routine laboratory medicine. The aims of this chapter is to comprehensively characterize the basic principles of mass spectrometric detection, recent development of MS, bottleneck of LC-MS method associate