| Popis: |
Gas-liquid chromatography-mass spectrometry with selected ion monitoring was used to detect and measure phaseollin and the proposed intermediates in phaseolln biosynthesis. Phaseolus vulgaris pod cavities were inoculated with a spore suspension of Monilinia fructicola and the isoflavonoids produced were extracted from the inoculation droplets with ethyl acetate. Trimethylsilyl ethers were prepared and chromatographed on an OV-101 column with detection by selected ion monitoring of two or three prominent ions in the mass spectrum of each compound. Successive injections of a reference compound and a portion of the ethyl acetate extract were used to estimate the concentrations of the components in the extract. Trimethylsilyl ethers of phaseollin, phaseollidin, coumestrol, 3,9-dihydroxypterocarpan, 7,2′,4′-trihydroxyisoflavone and 7,2′,4′-trihydroxyisoflavan were detected and estimated in the ethyl acetate extract without additional purification. Isoliquiritigenin, daidzein and phaseollinisoflavan required a thin layer chromatography step prior to derivatization and analysis by selected ion monitoring. Concentrations of the minor isoflavonoid components in the original inoculation droplets ranged from 0·03 μ m to 1·5 μ m . The advantages of selected ion monitoring for the detection and estimation of post-infectionally formed isoflavonoids are discussed. |
