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Abstract
Pyrroles and indoles react quantitatively with p-dimethylaminobenzaldehyde in the presence of hydrochloric acid (Ehrlich test) to form brightly coloured products. Many parameters affect this reaction leading to different sensitivities and stabilities of the complexes formed. the effect of the acid concentration, the reaction temperature, the amount of the reagent and the substituents present on the pyrrole or indole ring on the determination of pyrrole, 2-acetyl-N-methyl pyrrole and tryptophan were investigated. At the optimal conditions, 0.5 μg/ml of pyrrole, 1.0 μg/ml of 2-acetyl-N-methyl pyrrole and 1.2 μg/ml of tryptophan can be determined with a relative standard deviation of 1%.