Essay --

Capillary Liquid Chromatography- Mass Spectrometry What is Chromatography? Chromatography is the technical term for a set of laboratory approaches for the separation of mixtures (Solid/Liquid/Gas). The mixture is dissolved in a fluid which called the mobile phase, which carries it through a structure holding another material known as the stationary phase. The various constituents of the mixture transport at different velocities, causing them to separate. The separation is mainly based on differential partitioning between the mobile and it’s stationary phases. Subtle differences in a compound's partition coefficient result in differential retention time on the stationary phase and thus changing the separation (Tomer, et al., 1994). Chromatography can be preparative or analytical. The basic purpose of preparative chromatography is to separate the components of a mixture for more advanced uses (and also it is a method of purification). Analytical chromatography is done normally with smaller amounts of material and is for measuring the relative proportions of analytic in a mixture. The two are not mutually exclusive (Covey, et al., 1986). Basically chromatography methods can categorize based on several factors. †¢ by chromatographic bed shape 1. Column chromatography 2. Planner chromatography (Paper and Thin layer methods) †¢ Displacement Chromatography †¢ by physical state of mobile phase 1. Gas 2. Liquid †¢ by separation mechanism 1. Adsorption chromatography 2. Ion exchange chromatography 3. Size exclusion chromatography 4. Partition chromatography 5. Affinity chromatography Figure 1: Classification of Chromatography techniques. Liquid Chromatography Liquid chromatography (LC) is an analytical c... ... their mass / charge ratio (m/z). Several different techniques are available for both ionization and ion analysis, resulting in many different catogories of mass spectrometers with different combinations of these two processes. In practice, some combinations are far more versatile than others and the following descriptions focus on the major types of ion sources and mass analyzers that used in LC-MS systems. †¢ Ion Sources 1) Electrospray Ionization Source 2) Atmospheric Pressure Chemical Ionization Source 3) Atmospheric Pressure Photo Ionization †¢ Mass Analyzers 1) Quadruple Analyzers 2) Time-of-flight Analyzers 3) Ion Trap Analyzers 4) Hybrid Analyzers Applications of Capillary liquid chromatography- mass spectrometry ïÆ' ¼ Biochemical screening or genetic disorders, ïÆ' ¼ Drug Monitoring and Toxicology, ïÆ' ¼ Vitamins and Related Metabolites, ïÆ' ¼ Analysis of Steroid Hormones