QUANTIFICATION OF JASMONIC ACID BY CAPILLARY GAS CHROMATOGRAPHY-NEGATIVE CHEMICAL-IONIZATION MASS-SPECTROMETRY

Jasmonic acid can be assayed by the highly sensitive and reproducible gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NICI-MS) technique. We describe an optimized sample preparation me thod for routine analysis of jasmonic acids which allows the analysis of more than 10 samples/day. The basis of the method resides in a one- step extraction and phase partition, selective adsorbtion/elution of a cids with an aminopropyl column, conversion of acids to pentafluoroben zyl esters, final purification using a silica column, and GC-NICI-MS. Extracted standard curves were linear over an assay range of 1 to 1000 ng; correlation coefficients were typically greater than 0.9999. The limit of detection was 500 fg (2.4 fmol) jasmonic acid/injection at a signal to noise ratio of 10:1. Furthermore, the method was modified fo r steric analysis of jasmonic acid stereoisomers at the nanogram level . (3R,7S)-(+)-7-Iso-jasmonic acid was found to be biosynthesized from plant tissue cell cultures upon elicitation. This stereoisomer epimeri zes rapidly under alkaline and acidic conditions and in the presence o f albumin. Epimerization rate constants were determined at different p H values. (C) 1994 Academic Press, Inc.