Ultrahigh-Performance Liquid Chromatography (UHPLC)–Tandem Mass Spectrometry (MS/MS) Quantification of Nine Target Indoles in Sparkling Wines

An ultrahigh-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS/MS) method was developed for the simultaneous determination of nine target indoles in sparkling wines. The proposed method requires minimal sample pretreatment, and its performance parameters (accuracy, repeatability, LOD, and matrix effect) indicate that it is suitable for routine analysis. Four indoles were found at detectable levels in commercial Cava samples: 5-methoxytryptophol (5MTL), tryptophan (TRP), tryptophan ethyl ester (TEE), and N-acetylserotonin (NSER). Two of them, NSER and 5MTL, are reported here for the first time in sparkling wines, with values of 0.3-2 and 0.29-29.2 μg/L, respectively. In the same samples, the contents of melatonin (MEL), serotonin (SER), 5-hydroxytryptophan (5-OHTRP), 5-hydroxyindole-3-acetic acid (5OHIA), and 5-methoxy-3-indoleacetic acid (5MIA) were all below the corresponding limits of detection.