Patent ID: 7309608

Claim:
A method of one-step chemical synthesis of stable isotope labeled internal standards and chemical reaction for the purpose of identification and quantification of aldehydes and/or ketones in an aqueous sample comprising the steps of synthesizing isotopically labeled oxime internal standards by reation of authentic samples of aldehydes and ketones with an isotopically labeled alkoxylamine reagent b) combining a known amount of said oxime internal standards with said sample comprising said aldehydes and/or ketones; c) contacting said sample having the internal standards therein with an alkoxylamine to convert said aldehydes and/or ketones in said sample into oximes of identical structure as that of said oxime internal standards except for the stable isotope atoms wherein there is no conversion of said stable isotope labeled oxime internal standards to their corresponding non-labeled oxime compound during step c); and d) isolating said oximes and said oxime internal standards by aqueous extraction; e) analyzing said oximes and said oxime internal standards by mass spectrometry.