An analytical procedure has been developed for the determination of trace amounts of ethyl carbamate in fermented foodstuffs and alcoholic beverages. Concentrations were generally below the 1-5 micrograms/kg detection limit in bread, cheese, yoghurt, beer, gin and vodka. Higher concentrations were found in the other alcoholic beverages examined, which included whisky, fruit brandy, liqueur, wine, sherry and port.
Over 170 retail samples of beer have been analysed for N-nitrosodimethylamine (NDMA), apparent total N-nitroso compounds (ATNC) and nitrate. Levels of NDMA ranged from below 0.1 up to 1.2 micrograms/kg with a mean of 0.2 micrograms/kg. ATNC was detected in 42% of the samples in concentrations of up to 569 micrograms (N-NO)/kg. The levels of nitrate ranged from less than 0.2 up to 143 mg/kg with a mean of 16.8 mg/kg. There was no correlation between the amounts of NDMA and ATNC found in the retail beers. Samples taken during the course of fermentation showed that NDMA was unaffected by the bacterial reduction of nitrate which causes ATNC formation. HPLC studies using a photolysis/chemiluminescence detector revealed that the ATNC in beer are highly polar species of as yet unknown identity.
A rapid strong anion exchange HPLC/UV procedure has been developed for the determination of nitrate and nitrite in a wide variety of cured meats. The accuracy of this technique has been confirmed by the good agreement achieved with the existing British Standard colorimetric method. The applicability and repeatability of the procedure has been established in a survey of over 200 samples. The agreement between duplicate determinations and their respective means averaged +/- 3.4% for nitrite and +/- 4.3% for nitrate as defined by the term [(a - b)/(a + b)] X 100% where a and b are the repeat determination values.
Summawunlikely due to the wide between-laboratory variation". In order A design for cooperative study of analytical methods is described which involves the analysis of spiked samples and evaluation of the results using a linear regression technique.Two examples are described involving the study of ethyl carbarnate in whisky at levels from 40-170 yg/L and in beer at levels 4 -2 0 pg/L. Most participating laboratories used capillary gas chromatography with variations in sample preparation and detection methods. Acceptability criteria were defined as: intercept +2 standard deviations of the group mean, slope 0.9 to 1.1, individual analyses of duplicates within *lo YO of the mean and correlation coefficient better than 0.99. In the whisky trial, four of the seven laboratories taking part met these criteria, while for the beer trial all of the laboratories taking part were sufficiently close to these standards to be considered satisfactory given that the analyses were being performed close to the detection limit of the methods.
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