Minimizing loss of indoleacetic acid during purification of plant extracts.

Published methods for isolation of 3-indoleacetic acid (IAA) were found to give low yields due to losses at specific steps. Loss during extraction was minimized by grinding tissue under a nitrogen atmosphere, using 0.02% sodium diethyldithiocarbamate in 80% ethanol as the extractant. When ethereal solutions of IAA were concentrated in vacuo, the hormone was lost, presumably by sublimation. This significant source of loss was eliminated by concentration at atmospheric pressure. Oxidative losses during application of extracts to chromatograms were reduced by prior application of an antioxidant to the origin of chromatograms. These precautions permitted development of a method where 10-50 μg of IAA could be recovered from soybean leaves with approximately 60% yield.