Determination of polyphenols in grape-based nutraceutical products using high resolution mass spectrometry

• Determination of polyphenols in grape-based nutraceuticals by UHPLC-Orbitrap-MS.
• Determination of all classes of polyphenols in grape in less than 16 min.
• Retrospective analysis to identify other phenolic compounds in grape-based nutraceuticals.
• High variability of resveratrol content in grape-based nutraceuticals.

The detection and quantification of polyphenols in grape-based nutraceutical products were performed using ultra high performance liquid chromatography coupled to single-stage Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS). The method is based on an extraction using a mixture of methanol:water (80:20, v/v), followed by two dilutions (10 or 50 times). The method was validated in terms of linearity, precision and trueness, and limits of detection and quantification ranged from 1 to 10 μg L−1 and 2–50 μg L−1 respectively. High variability of the amount of anthocyanins and flavanols were obtained in the analyzed samples, with values ranging from 2 to 27448 mg kg−1, whereas the resveratrol was only detected in 6 out of 8 samples at concentrations ranging from 3 to 11107 mg kg−1. Furthermore, other polyphenols belonging to other families like dihydrochalcones, flavanones, flavonols, isoflavonoids or phenolic acids (hydroxybenzoic and hydroxycinnamic acids) were quantified. Apart from this, a tentative identification of 8 compounds was performed.