by Sean Aleman, Contributing Writer
Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical technique used for the identification and quantification of environmental volatile and semi-volatile organic pollutants in liquid, gaseous, and solid samples. With its ability to separate complex mixtures and detect trace levels of pollutants, GC-MS is an essential tool for environmental monitoring. This buyer's guide provides in-depth information to assist educated purchasers and laboratory managers in selecting the right GC-MS system for monitoring environmental pollutants.
Understanding GC-MS Analysis
GC-MS is a two-step process that combines gas chromatography (GC) and mass spectrometry (MS). In the GC step, the sample is vaporized and injected into a capillary column coated with a stationary phase. The compounds in the sample are separated based on their boiling points and polarities as they elute from the column. An inert carrier gas, such as helium, hydrogen, or nitrogen, transports the components through the column. In the MS step, the separated compounds enter the mass spectrometer, where they undergo ionization and fragmentation. The mass analyzer, typically a quadrupole or ion trap, separates the ions based on their mass-to-charge ratios (m/z). Data acquisition can be performed in full scan mode, covering a wide range of m/z ratios, or selected ion monitoring (SIM) mode, focusing on specific masses of interest. The fragmented ions are detected and analyzed, and each peak in the gas chromatogram corresponds to a unique mass spectrum, which is used for compound identification. Extensive libraries of mass spectra facilitate the identification and quantification of unknown compounds and target analytes.
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