Estimation of Triterpenes in Wines, Spirits, and Oak Heartwoods by LC–MS

mode and two-dimensional nuclear magnetic resonance spectroscopy allowed us to purify and determine structures of triterpenes 1–4 in pedunculate oak heartwood (8). Our main interests are in the acid triterpene content of oak heartwoods used in cooperage, their astringent properties, and their occurrence in wines and spirits. In this article, we report a highly sensitive and quantitative detection method of four triterpenes in oak heartwoods, wines, and spirits. Because of the lack of UV absorbance and the presence of two acidic groups on the compounds, LC–electrospray ionization MS is well suited for monitoring acidic triterpenes (9). Moreover, LC– electrospray ionization MS is especially powerful for determining high molecular weight compounds such as glycosylated triterpenes, which are polar and cannot be determined by other methods such as gas chromatography (GC)–MS without destruction (9–12). At the beginning of our study, we established a reliable and fast method for purifying triterpenes in woods. To avoid long extraction and cleanup processes, we performed direct solid–liquid extractions using diethyl ether–powder and ethyl acetate– powder and varying both the extraction strengths of the organic solvents and the mesh of the wood powders. We therefore Pedunculate Quercus robur L. and sessile Q. petraea Liebl oak heartwoods are used commonly in the aging process of wine and spirits. During maturation, the ethanol content of these beverages extracts bitter and astringent compounds such as triterpenes. The authors have extracted, separated, and quantified four major triterpenes from heartwoods using a liquid chromatography–mass spectrometry method in a selected-ion monitoring mode. They used echinocystic acid as an internal standard. Because of their hydroxyl and carboxyl functions, these molecules provided intense deprotonated molecular ions. The authors discuss reproducibility and detection limits and apply the proposed method to the quantification of triterpenes in wines, spirits, and heartwoods of several origins. Estimation of Triterpenes in Wines, Spirits, and Oak Heartwoods by LC–MS