Simple identification of the neutral chlorinated auxin in pea by thin layer chromatography

One of the neutral chlorinated auxins of immature pea seeds was readily identified by thin layer procedures simple enough to serve in student's laboratory courses. 4‐Chloroindole‐3‐acetic acid methyl ester was extracted from 50 g of commercial, frozen peas by either water or acetone, concentrated to small volumes and chromatographed in CHCl3 or CCl4 solvent systems separating the chlorinated auxin from indoleacetonitrile and the methyl or ethyl esters of indoleacetic acid. Colour reaction was carried out with some of the Salkowski FeCl3 sprays of which Ehmann's FeCl3/dimethylaminobenzaldehyde modification gave the most stable blue colour.