Derivation and chromatographic separation of acid indole auxins

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Virginia Polytechnic Institute and State University

For many years silylation of polar and thermolabile compounds has been used to facilitate their gas chromatographic analysis. The three phytochemically significant indole acids; 3-indole acetic acid, 3-indole propionic acid, and 3-indole butyric acid along with an analog, D-tryptophan, are four compounds which have been analyzed by this method. A detailed study of the trimethylsilylation reaction of these compounds was the objective of this research.

Optimum conditions for the trimethylsilylation of the four acid indoles, including temperature, time of silylation, humidity and reagent excess were examined. Practical considerations for the gas chromatographic separation of these compounds, including column length, choice of liquid phase, and column temperature were studied and optimized. The effects of derivative storage were examined and optimum storage conditions, alone; with the stability of the primary reaction product, were determined. The structure of reaction side products and decomposition products were thoroughly investigated. To this end an all glass post column effluent splitter was designed and installed for the trapping of derivatives. Finally, the feasibility of using high speed liquid chromatography for the separation and analysis of these four compounds was also investigated.