MEASUREMENT OF INDOLEBUTYRIC ACID IN PLANT-TISSUES BY ISOTOPE-DILUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY ANALYSIS

An internal standard, [C-13][indole-2]-indole-3-butyric acid, was synthesized from indole-2[C-13] and was shown to be effective for the quantitative determination of indole-3-butyric acid from plant tissue. When this standard was used along with [C-13]indole-3-acetic acid, both indolic auxins could be quantified from the same tobacco (Nicotiana tabacam) leaf sample by isotope dilution analysis using selected ion monitoring gas chromatography-mass spectrometry for detection.