Acetic　acid　is　the　key　organic　substance　used　to　verify　the　authenticity　of　vinegar.　A　new　method　for　precisely　determining　acetic　acid　δDCH3　in　vinegar　via　gas　chromatography　−pyrolytic-stable　isotope　ratio　mass　spectrometry　(GC-P-IRMS)　was　established.　The　δDCH3　values　were　obtained　via　calibration　with　a　series　of　standards.　The　optimised　method　demonstrated　a　repeatability　standard　deviation　within　3　‰.　The　standard　deviation　of　accuracy　of　the　new　method　compared　with　that　of　the　SNIF-NMR　method　was　within　2.6　‰.　The　synthetic　acetic　acid　δDCH3　values　was　−136.7　‰　±　29.6　‰,　and　the　δDCH3　value　of　acetic　acid　in　vinegar　was　−414.9　‰　±　40.5　‰,　with　significant　isotopic　distribution　characteristics.　This　methodology　serves　as　a　supplementary　method　for　measuring　the　δDCH3　value　of　acetic　acid　in　vinegar.　It　has　advantages　over　other　methods　in　terms　of　time,　sensitivity　and　operability.　And　provides　a　new　idea　for　solving　the　problem　of　analyzing　substances　in　the　presence　of　exchangeable　groups.　©　2024　Elsevier　Ltd