Gas chromatography-mass spectrometry (GC-MS)

Gas chromatography-mass spectrometry, or GC-MS, is an analytical method that vaporizes a sample, separates its compounds in a gas stream and identifies each by its mass signature.

The chromatography stage separates volatile and semi-volatile compounds by how they move through a heated column. The mass spectrometer then fragments each compound and records a pattern of fragment masses that acts like a fingerprint, allowing confident identification and quantitation. It is a standard method for residual solvents, terpenes and many pesticides, and it is the classic confirmatory technique in drug testing.

Its main limitation for cannabinoids is heat: the injection port converts acidic cannabinoids such as CBDA and THCA to their neutral forms, so a GC-MS potency result reports total values unless the sample is chemically derivatized first. On a certificate of analysis the method is usually named next to each test category. Seeing GC-MS listed for solvents or terpenes is ordinary; seeing it for potency means the acid and neutral forms were probably not measured separately.