Mass spectrometry (MS) is a powerful qualitative and quantitative technique for obtaining information about the molecular weights and chemical structures of the peptides, proteins, carbohydrates, oligonucleotides, natural products, and drug metabolites.
Introduction of Mass Spectrometry
A mass spectrometer consists of three parts, an ionizer (ionization source), a mass analyzer, and a detector. The basic principle is to ionize the components in the sample in the ionizer to generate positively charged ions with different charge to mass ratios, and then form an ion beam through the action of accelerating electric field, which enters the mass analyzer. In a mass analyzer, ions with different charge/mass ratios are separated in space or time by an electric or magnetic field. Ions are individually focused to a detector by filtering, resulting in a map related to mass concentration (or partial pressure).
Classification of Mass Spectrometer
- Double focus mass spectrometer
- Quadrupole mass spectrometer
- Time-of-flight mass spectrometer
- Ion trap mass spectrometer
- Fourier transform mass spectrometer (FT-MS)
- Matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOFMS)
- Gas chromatography-mass spectrometry (GC-MS): Gas chromatography-quadrupole mass spectrometer, Gas chromatography-time-of-flight mass spectrometer, Gas chromatography-ion trap mass spectrometer
- Liquid chromatography-mass spectrometer (LC-MS): Liquid chromatography-quadrupole mass spectrometer, Liquid chromatography-ion trap mass spectrometer, Liquid chromatography-time-of-flight mass spectrometer, Liquid chromatography-mass spectrometry-mass spectrometer
Advantages of MS
- Accurate determination of molecular weight
- High sensitivity
- Facilitate mixture analysis (GC-MS, LC-MS and MS-MS are especially effective for difficult to separate mixtures, such as drug metabolites and identification of trace active components in Chinese herbal medicines)
- Multifunctional (widely applicable to various compounds)
Applications
- Detection of small molecules in biological metabolism (including amino acids, fatty acids, cholesterol, steroids, lipids, carbohydrates, vitamins, and trace elements)
- Detection of biological macromolecules (including proteins, sugars, nucleic acids, and lipids)
- Drug analysis and testing
- Identification of microorganisms
- Pharmacokinetics (LC-MS with a triple quadrupole mass spectrometer, Tandem mass spectrometry)
References
- Biemann, K. Mass spectrometry. Annual review of biochemistry. 1963; 32(1), pp.755-780.
- Glish GL; et al. The basics of mass spectrometry in the twenty-first century. Nat Rev Drug Discov. 2003 Feb; 2(2): 140-50.
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