A method for the determination of methyl carbamate and ethyl carbamate in wines

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Abstract
A method is described for the simultaneous determination of methyl carbamate (MC) and ethyl carbamate (EC) in wines that is based on: (a) extraction of the sample with dichloromethane using an extraction tube or an alumina—Celite column, (b) concentration of the extract to a small volume, and (c) determination by gas‐liquid chromatography‐thermal energy analyser (N‐mode). The method is highly sensitive (1–2 ng/ml), accurate (recoveries >80%), and precise (CV, 5–10%). Nineteen of 27 samples of wines analysed contained traces (up to 2.7 ng/ml) of MC, and most contained EC (up to 70 ng/ml). Wines treated in the laboratory with 200 ppm dimethyl pyrocarbonate (DMPC)—a cold sterilant recently approved for use in wines—indicated that such a treatment may increase the MC contents of the wines to 10 ng/ml. Additional studies suggested that formation of MC in DMPC‐treated wines is dependent on both pH and ammonia content of the wines. The identity of MC in a few selected samples was confirmed by gas‐liquid chromatography—high resolution (10 K) mass spectrometry. The natural low levels of MC found in these wines are not considered to pose a risk to human health.