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Low concentrations of ethyl carbamate, which may occur in distilled spirits are shown to originate from traces of cyanide, produced in distillates by thermal decomposition of the cyanohydrin of isobutyraldehyde (IBAC) which is present in fermented wash. This compound arises during fermentation by the hydrolytic action of yeast beta-glucosidase on a naturally-occurring cyanogenic glycoside, identified as epiheterodendrin (EPH). EPH, which is a heat-stable precursor of IBAC is located in the acrospires of malted barley and is readily transferred to worts during mashing. Although many barley varieties display the ability to produce volatile cyanide, some low-yielders have been identified. EPH is absent from unmalted barley and its development is strongly influenced by malting conditions. Conversion of measurable cyanide (MC) into ethyl carbamate takes place during-or after distillation but, apparently, not before.Key Words: Ethyl carbamate, distillation, cyanide, yeast, cyano genic glycoside, epiheterodendrin, malt, barley, variety. IntroductionEthyl carbamate (CjHjOCONHJ is of widespread occurrence in fermented foods and beverages. It is not usually detected in highly rectified alcohol but it has been found in trace amounts in other spirits including Scotch Whisky3-20. In view of its reported carcinogenicity, attempts are being made to control the incidence of ethyl carbamate in alcoholic beverages by introducing mandatory maximum allowable concentrations5-10. This paper describes work carried out to determine the origin of ethyl carbamate or its precursors), as a means towards control ling its formation during the whisky manufacturing process.Although published sources18 indicated that ethyl carbamate may be formed during fermentation from carbamyl phosphate and related compounds which are produced in yeast, initial studies with distilled spirits suggested that ethyl carbamate levels were related to cereal usage. Early attention was focussed on ureido compounds, containing the NH2CONH-group, which were regarded as likely precursors because of their chemical similarity to carbamate.TLC was used to demonstrate the presence of a group of ureido compounds in fermented wash but resolution of indivi dual components by this technique was inadequate for their identification. However, HPLC and ion-exchange chromatography confirmed that the predominant ureido compound was allantoin. Subsequent analysis showed that cereals were the main source of allantoin in wash. For barley and wheat, ureido content was found to increase in proportion to total nitrogen content. Micro-malting studies showed that the ureido content of grain increased by 30% during malting. Typically, green (unkilned) malt containing 250 ppm allantoin yielded dried malt with a content of 180 ppm, the relatively high value for the green malt being completely accounted for by the high content of ureido material which is present in the rootlets (2000-3000 ppm) and lost on drying, with their removal. Measure ments carried out on distillery wash samples showed th...

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Carfentrazone-ethyl (CF-E) is an aryl triazolinone reduced-risk herbicide for use on corn, wheat, and soybean. As part of the assessment of its metabolic fate, the aerobic aquatic metabolism of [(14)C]CF-E at a concentration of 0.22 microg/g was investigated. Two separate aquatic sediments (silty clay loam and clay loam soils, flooded with water) were used in the study. At each of eight samplings throughout the 30-day study, the distribution of radioactivity between surface water, sediment, and volatile fractions was assessed. At zero time, the majority of the applied radioactivity was contained in the water layer (83-90%), declining to 70-80% after 30 days. This was coupled with an increase in the percent radioactivity in the soil layer from 4-6% at day 0 to 13-19% after 30 days. Nonextractable soil residues and volatile degradation products were formed in negligible amounts. Analysis of the incubation extracts from either aquatic sediment indicated a rapid conversion (<2 days) of the parent CF-E ester to carfentrazone-chloropropionic acid. Over time, increasing amounts of a cascade of acidic degradation products comprising >90% of the applied radioactivity were formed. Identification of these degradation products was initially achieved through chromatographic comparison with reference synthetic standards and subsequently confirmed using LC-MS analysis. A degradation pathway for CF-E under aerobic aquatic conditions is proposed.