BIOMEDICAL AND BIOCHEMICAL APPLICATIONS OF LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

This review centres on the application of various LC-MS and LC-MS-MS t echniques to the study and solution of practical problems in biomedica l research. For this purpose it covers a selection of publications in this area included in the MEDLINE database for the period 1991-mid-199 4. As shown herein, LC-MS is increasingly gaining in importance in the biomedical field, especially after the revolution brought about by th e introduction of the new liquid-phase atmospheric pressure ionization (API) techniques, such as electrospray (ES) and ionspray. The informa tion in this database shows that thermospray (TS), which clearly domin ated LC-MS coupling in the 1980s, is on a downward trend relative to t he more modern API techniques which will certainly dominate this appli cation field in the present decade. Studies on drug metabolism, therap eutic drug monitoring and pharmacology have been traditionally carried out by GC-MS. However, LC-MS has lately been replacing classical GC-M S techniques in many of these applications. For instance, LC-ES-MS has greatly facilitated the application of both qualitative and quantitat ive LC-MS methods to highly polar molecules. This is possible without the need to resort to elaborate sample handling and derivatization pro cedures for relatively high-molecular-mass compounds such as drug conj ugates, biosynthetic and natural peptides and therapeutic proteins obt ained by recombinant DNA technology, all of them formerly totally inac cessible to the standard GC-MS or LC-MS methods. With regard to studie s on metabolism and biochemical phenomena of endogenous compounds, LC- ES-MS is also becoming very strong in the analysis of structural biopo lymers such as peptides, proteins, glycoproteins and glycolipids, and also lower molecular mass compounds such as fatty acids, vitamins, ste roids and nucleic acids. For example, structural verification of post- translational modifications in proteins can be efficiently obtained in the time frame of an LC run and suitable MS methods for the location of glycopeptide-containing fractions in proteolytic digests of glycopr oteins have been developed. Interesting examples are also shown of the use of LC-MS in clinical studies and the determination of biological markers of disease.