GC-MS
Gas chromatography–mass spectrometry (GC-MS) is an analytical technique combining gas chromatography for separation of volatile compounds with mass spectrometry for identification and quantification. It is widely used in environmental testing, forensic science, pharmaceuticals, and metabolomics.
How does GC-MS work?
GC-MS integrates two powerful analytical methods: gas chromatography (GC) and mass spectrometry (MS). In the first stage, a sample is vaporised and carried through a column by an inert gas (typically helium or nitrogen), where components separate based on their volatility and interaction with the column's stationary phase. As compounds elute from the column, they enter the mass spectrometer, where they are ionised (commonly via electron ionisation), fragmented, and detected based on their mass-to-charge ratio (m/z). The resulting mass spectrum acts as a molecular fingerprint, enabling precise compound identification.
What are the applications of GC-MS?
GC-MS is essential in quality control and regulatory compliance across industries. In pharmaceuticals, it verifies purity and detects residual solvents (e.g., in accordance with ICH Q3C). In environmental monitoring, it identifies pollutants such as pesticides, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). Forensic labs use GC-MS to detect drugs and toxins in biological samples. In metabolomics and metabolite profiling, it enables untargeted and targeted analysis of small molecules in complex matrices like urine or serum.
What are the limitations of GC-MS?
GC-MS is limited to volatile and thermally stable compounds. Non-volatile or thermally labile substances require derivatisation or alternative techniques such as LC-MS. Additionally, sample preparation can be time-consuming, and data interpretation requires expertise due to complex spectra. Despite this, GC-MS remains a gold standard for targeted analysis due to its high sensitivity, reproducibility, and robustness.
Related concepts
GC-MS is often used alongside other analytical methods such as HPLC-MS, NMR, and ELISA. It is frequently supported by reference standards, certified reference materials (CRMs), and data from databases like NIST or Wiley. Regulatory frameworks such as ISO 17025, REACH, and USP <621> govern its use in accredited laboratories.