This document specifies a method for determining ε‑caprolactam and ω‑laurolactam in polyamides by gas chromatography. It is applicable particularly to the determination of ε‑caprolactam in polyamide 6 and ω‑laurolactam in polyamide 12. Two variants of the basic method are specified. — Method A is an extraction method with boiling methanol, and the extract is injected into a gas chromatograph. — Method B is a method using a solvent, and the solution is injected into a gas chromatograph.