In an effort to identify it, an unknown compound, U, was subjected to extensive

Question

In an effort to identify it, an unknown compound, U, was subjected to extensive spectroscopic analysis. In addition, the mass spectrum of compound U was acquired. A molecular ion peak was observed at m/z = 166, and the molecular formula for compound U was thereby determined to be C9H10O3. A peak at m/z = 121 was by far the most intense peak in the mass spectrum. Determine the structure of compound U. Be sure to include a concise discussion of the reasoning. Construct tables summarizing the IR and 1H NMR data, and assign the peaks in the IR and NMR spectra to the appropriate structural elements in U. Explain the appearance of the base peak at m/z = 121 in the mass spectrum.

Explanation / Answer

Chromatographic elution performed under isocratic reversed-phase conditions using a C18 narrow-bore LC column allowed retention times lower than 12 min to be obtained. Qualitative analysis was performed in negative-ion (NI) full-scan and product-ion scan acquisition modes, whereas method validation in terms of linearity, detection limits, accuracy, and robustness was carried out under NI selected reaction monitoring conditions. The matrix-matched detection limit was calculated in the low parts per billion range (10 microg/L). Results of the application of the method to red wine, grape, and winemaking byproduct samples were compared with those obtained using an LC-UV/DAD technique. Determination of trans-resveratrol in the samples investigated showed that the highest concentration was found in red wine, whereas wine made from grape pomace contained the lowest content.

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