DETECTION OF ALKYL METHYLPHOSPHONIC ACIDS IN COMPLEX MATRICES BY GAS-CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY

A method was developed to detect alkyl methylphosphonic acids in compl ex matrices using gas chromatography-tandem mass spectrometry. By conv erting the acids to their trimethylsilyl derivatives and monitoring th e collision-induced dissociation of m/z 153 to m/z 75 under electron i onization or methane chemical ionization (CI) conditions, five members of this series (alkyl=ethyl, isopropyl, isobutyl, pinacolyl and cyclo hexyl) were selectively detected against backgrounds of diesel fuel an d soil extracts containing base-neutral-acid polynuclear aromatic hydr ocarbons and pesticides without interference. Detection limits were 20 0-500 pg injected. Ammonia CI was successfully employed for molecular mass confirmation. Published by Elsevier Science B.V.