N-nitrosodimethylamine analysis in Estonian beer using positive-ion chemical ionization with gas chromatography mass spectrometry

N-nitrosodimethylamine (NDMA) is a potent animal carcinogen that has been detected in trace levels in beers. A total of 264 beer samples were analyzed for their NDMA content. For cleaning of the sample the two-step solid-phase extraction with Extrelut and Florisil sorbents were used. NDMA was separated by gas chromatography and detected by positive-ion chemical ionization using ammonia as reagent gas. The HP 6890 Plus GC/HP 5973 MSD with positive-ion chemical ionization option was used in the selected ion-monitoring mode. The limit of detection for NDMA using this method was 0.15 ppb with about 70–80% recovery. Of 158 Estonian beers analyzed during 2003–2004, the average NDMA level was found to be 0.20 ppb. Of 106 imported beer samples the average NDMA level was found to be 0.21 ppb.