The measurement and mass spectral identification of indole-3-pyruvate from tomato shoots

Endogenous indole-3-pyruvate has been identified by full-scan combined gas chromatography-mass spectrometry and measured using gas chromatography with an electron capture detector. High specific-activity [5- 3H]indole-3-pyruvate was synthesized from [5- 3H] tryptophan and used as an internal standard. In order to allow purification of the labile indole-3-pyruvate it was stabilised by the formation in the crude extract of its pentafluorobenzyl oxime derivative. This derivative also allowed sensitive detection and measurement of indole-3-pyruvate in the picogram range using a gas chromatograph with an electron capture detector. Endogenous levels were found to be between 8–10 ng/g f.wt. of tomato shoots which is comparable to that of the indole-3-acetic acid pool size,11 ng/g f.wt., in this tissue.