Clinical liquid chromatography proteins

Consider one small molecule, phenylalanine. It is an essential amino acid in our diet and is important in protein synthesis (a component of protein), as well as a precursor to tyrosine and neurotransmitters. Phenylalanine is one of several amino acids that are measured in a variety of clinical methods, which include immunoassay, fluorometry, high performance liquid chromatography (HPLC see Section 4.1.2) and most recently MS/MS (see Chapter 3). Historically, screening labs utilized immunoassays or fluorimetric analysis. Diagnostic metabolic labs used the amino acid analyzer, which was a form of HPLC. Most recently, the tandem mass spectrometer has been used extensively in screening labs to analyze amino acids or in diagnostic labs as a universal detector for GC and LC techniques. Why did MS/MS replace older technological systems The answer to this question lies in the power of mass spectrometer. 

Clark and Kricka have reviewed High-Resolution Analytical Techniques for Proteins and Peptides and Their Applications in Clinical Chemistry and include consideration of isotachophoresis, high-performance liquid chromatography, and high-resolution two-dimensional electrophoretic techniques for separation and analysis of complex protein mixtures. These techniques are not now widely used in clinical chemistry laboratories but represent the tools of the future, when laboratories will be required to measure gene products and the myriad proteins present, as in complex biologic fluids of significance in health and diseases. 

Enzyme Immunoassays. Liquid Chromatography Size-Exclusion Affinity Chromatography Clinical Applications. Peptides. Proteins Physiological Samples. Quality Assurance Reference Materials. 

See alsa Chromatography Multidimensional Techniques. Environmental Analysis. Extraction Solid-Phase Extraction. Food and Nutritional Analysis Sample Preparation Contaminants Pesticide Residues. Forensic Sciences Drug Screening in Sport Illicit Drugs. Herbicides. Liquid Chromatography Instrumentation Clinical Applications Food Applications. Mass Spectrometry Peptides and Proteins. Pesticides. Pharmaceutical Analysis Sample Preparation. Proteomics. Sample Handling Automated Sample Preparation. Water Analysis Organic Compounds. 

Derivatization. Ion Exchange Overview. Liquid Chromatography Clinical Applications. Proteins Traditional Methods of Sequence Determination. 

See a/so Clinical Analysis Sample Handling. Gas Chromatography Mass Spectrometry. Liquid Chromatography Liquid Chromatography-Mass Spectrometry. Mass Spectrometry Ionization Methods Ovenriew Atmospheric Pressure Ionization Techniques Time-of-Flight Selected Ion Monitoring Stable Isotope Ratio. Peptides. Proteins Traditional Methods of quence Determination. Quality Assurance Internal Standards. 

The use of solid-phase extraction cartridges is now well established in the analysis of clinical specimens. However, although this method provides efficient purification of the sample, it may lead to a loss of protein-bound vitamins. Direct injection of plasma samples into liquid chromatography (LC) columns is possible in some applications. Dilute filtered or centrifuged urine can be injected in certain LC applications, as is the case in urinary riboflavin assay. 

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