A simple method for simultaneous RP-HPLC determination of indolic compounds related to bacterial biosynthesis of indole-3-acetic acid

In this short technical report, we present a fast and simple procedure for sample preparation and a single-run Reversed Phase High Performance Liquid Chromatography (RP-HPLC) determination of seven indoles (indole-3-acetic acid, indole-3-acetamide, indole-3-acetonitrile, indole-3-ethanol, indole-3-lactic acid, tryptamine and tryptophan) in bacterial culture supernatants. The separation of the analytes, after a single centrifugal filtration clean-up step, was performed using a gradient elution on a symmetry C8 column followed by fluorimetric detection (λ_ex = 280/λ_em = 350 nm). The calibration curves were linear for all of the studied compounds over the concentration range of 0.0625–125 μg mL^?1 (r ²  ≥ 0.998) and the limits of detection were below 0.015 μg mL^?1. The applicability of the method was confirmed by analysis of Pseudomonas putida culture supernatants.