Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) assays are robust bioanalytical techniques. Each of these techniques is a crucial component of mass spectrometry testing services. With a broad range of applications, such as pharmacokinetics studies, identifying the right mass spectrometry testing services depends on multiple factors. The current article discusses these unique characteristics for identifying the right mass spectrometry combination. The article begins by discussing GC-MS and LC-MS mass spectrometry individually, followed by the similarities and differences between these robust techniques.
GC-MS assays
GC-MS employs gas chromatography to separate chemical compounds and detect unknown compounds using mass spectrometry. The combination of gas chromatography and mass spectrometry helps researchers identify compounds in complex study mixtures.
GC-MS systems introduce a sample mixture coupled with a gas carrier into a chromatogram. The mobile phase hits the gasses for separating individual components of a sample mixture. These individual components are then subjected to a mass spectrometer, where individual compounds are measured based on their mass-to-charge ratio.
LC-MS assays
The primary objective of LC-MS systems is similar to GC-MS. However, LC-MS assays employ a liquid mobile phase instead of gas chromatography. Instead of heating the mixture, liquid chromatography ionizes the ions and introduces them into mass spectrometers.
Similarities versus differences between GC-MS and LC-MS assays
Both these techniques have the same objective of separating, detecting, and comparing unknown compounds with known ones. Some samples are more suitable for LC-MS, while others are for GC-MS. For example, GC-MS is ideal for volatile compounds. On the other hand, GC-MS and LC-MS employ a mobile and stationary phase to separate complex mixtures. However, GC-MS employs a gas mobile phase, whereas LC-MS uses a liquid mobile phase. Once chemical compounds are separated, both techniques employ a mass spectrometer to identify and quantify unknown compounds.
Although GC-MS and LC-MS may seem quite similar, there are significant differences between each of these systems. GC-MS assays are more affordable than LC-MS systems. LC-MS systems require specialized training and have more focus on replacement and maintenance. Notably, each of these systems has a unique mobile phase. GC-MS assays use inert gasses to move the vaporized sample along the stationary phase. Hence, GC-MS is ideal for gaseous and more volatile samples. However, vaporization means it is also a harsh method. On the contrary, LC-MS assays are more gentler and perfect for water samples.
The differences in the mobile phase help researchers use each of these systems for different applications. LC-MS is ideal for water samples, and hence, they are used widely in biochemical and environmental analysis. For example, research facilities often employ LC-MS assays to test for contaminants or pollution in a lake or river. On the other hand, GC-MS is suitable for studying volatile compounds like harmful chemicals and drugs. Besides, they are primarily used to assess chemical residues or narcotics.
Conclusion
Both GC-MS and LC-MS assays are popular bioanalytical tools. Hence, labeling one better than the other can be misleading. GC-MS is a faster technique, while LC-MS can detect a wide range of compounds. Therefore, identifying individual goals when deciding on a particular method is more important.
