Abstract: A new method was established for the determination of indoles (indole (IND), 3-methylindole (3-MI), indolyl-3-acetic acid (IAA) and indolyl-3-propionic acid (IPA)) in plasma by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The analytes were separated simultaneously on a Shim-pack VP-ODS column (150 mm×4.6 mm, 4.6 μm) using 15 mmol/L sodium dihydrogen phosphate solution and methanol (48:52, v/v) as the mobile phases. The column temperature was 30 ℃, and the flow rate was 0.8 mL/min. The calibration curves of IND, 3-MI, IPA and IAA showed good linear relationships. The intra-day and inter-day relative standard deviations (RSDs) for the analytes were both less than 6.31%. The average recoveries of the analytes in plasma were 97.5%-107.0%. The method was successfully applied to the analysis of indoles in the plasma of healthy women of reproductive age (n=25) as controls and patients with polycystic ovarian syndrome (n=61). The results showed that the concentrations of indoles in the plasma were significantly different between the two groups, and IND was found to be a risk factor and a potential diagnostic biomarker for polycystic ovarian syndrome (PCOS). The method is simple, sensitive and suitable for use in clinical testing and laboratory research.

Key words: high performance liquid chromatography-fluorescence detection (HPLC-FLD), polycystic ovarian syndrome (PCOS), indoles, plasma