Department of Viticulture and Enology, University of California , Davis, California 95616, United States.
Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens , Panepistimioupolis Zografou, 15 771, Athens, Greece.
Anal Chem. 2015 Nov 3;87(21):10799-806. doi: 10.1021/acs.analchem.5b01682. Epub 2015 Oct 23.
Recent developments that have accelerated 2D NMR methods and improved quantitation have made these methods accessible analytical procedures, and the large signal dispersion allows for the analysis of complex samples. Few natural samples are as complex as wine, so the application to challenges in wine analysis look promising. The analysis of carbonyl compounds in wine, key oxidation products, is complicated by a multitude of kinetically reversible adducts, such as acetals and sulfonates, so that sample preparation steps can generate complex interferences. These challenges could be overcome if the compounds could be quantified in situ. Here, two-dimensional ((1)H-(1)H) homonuclear and heteronuclear ((13)C-(1)H) single quantum correlations (correlation spectroscopy, COSY, and heteronuclear single quantum coherence, HSQC) nuclear magnetic resonance spectra of undiluted wine samples were observed at natural abundance. These techniques achieve simultaneous direct identification and quantitation of acetaldehyde, pyruvic acid, acetoin, methylglyoxal, and α-ketoglutaric acid in wine with only a small addition of D2O. It was also possible to observe and sometimes quantify the sulfite, hydrate, and acetal forms of the carbonyl compounds. The accuracy of the method was tested in wine samples by spiking with a mixture of all analytes at different concentrations. The method was applied to 15 wine samples of various vintages and grape varieties. The application of this method could provide a powerful tool to better understand the development, evolution, and perception of wine oxidation and insight into the impact of these sulfite bound carbonyls on antimicrobial and antioxidant action by SO2.
最近的发展加速了二维 NMR 方法并提高了定量能力，使这些方法成为可用于分析的程序，而大的信号分散允许对复杂样品进行分析。很少有天然样品像葡萄酒那样复杂，因此，这些方法在葡萄酒分析中的应用前景广阔。葡萄酒中羰基化合物（关键氧化产物）的分析由于大量动力学可逆加合物（如缩醛和亚硫酸盐）而变得复杂，因此样品制备步骤可能会产生复杂的干扰。如果可以在原位定量这些化合物，则可以克服这些挑战。在这里，在天然丰度下观察到了未稀释葡萄酒样品的二维（(1)H-(1)H）同核和异核（(13)C-(1)H）单量子相关（相关光谱学，COSY 和异核单量子相干，HSQC）核磁共振谱。这些技术仅需少量添加 D2O，即可实现对葡萄酒中乙醛、丙酮酸、乙酰醇、甲基乙二醛和α-酮戊二酸的直接同时鉴定和定量。还可以观察到并有时定量羰基化合物的亚硫酸盐、水合物和缩醛形式。通过在不同浓度下用所有分析物的混合物对葡萄酒样品进行加标，测试了该方法的准确性。该方法应用于 15 种不同年份和葡萄品种的葡萄酒样品。该方法的应用可以为更好地了解葡萄酒氧化的发展、演变和感知提供有力的工具，并深入了解这些与亚硫酸盐结合的羰基对 SO2 的抗菌和抗氧化作用的影响。
