Determination of volatile nitrosamines in foods and other environmental samples

Abstract

Methods were investigated for determination of volatile nitrosamines which have been reported to occur in foods and other environmental samples. Nitrosamines were removed from foods using a Likens-Nickerson extractor; 81% of added dimethylnitrosamine and 110% of added diethylnitrosamine were recovered from 10 ng/g spiked aqueous solutions. The factors affecting recovery of these nitrosamines were investigated. The usefulness of Freon-11 as an extracting solvent for nitrosamines was investigated using both batch serial and continuous liquid-liquid extraction. Potential gas chromatographic (GC) interferences were removed from food extracts by an acid extraction step and, when needed, by liquid column chromatography on alumina and silica gel. Dilute solu­tions containing nitrosamines were analyzed directly using a GC solvent stripping technique. Nitrosamines were detected with the Coulson electrolytic conductivity detector operated in the pyrolytic mode and with a flame ionization detector. The sensitivities of these detectors were compared for selected alkyl and heterocyclic nitros­amines. The specificity of the Coulson detector was demonstrated for analysis of extracts of meat and fish samples. Additional clean-up of food extracts is re­quired to insure identification of nitrosamines by combined GC-mass spectrometry. A method employing chromatographic equilibration (frontal analysis) was investigated for determination of dimethylnitrosamine in the air.