N-nitrosodimethylamine in Spanish beers.

A survey of 21 beers produced in Spain during 1994 was conducted to assess contamination with volatile N-nitrosamines. N-Nitrosodimethylamine (NDMA), the only volatile N-nitrosamine detected, was found in 52% of Spanish beers at or above the detection level (0.05 microgram/kg). The mean NDMA level for all samples was 0.11 microgram/kg, and the range was from not detected to 0.55 microgram/kg. No differences in the NDMA content were observed between the different beer types. Individual daily intake of NDMA may reach up to 0.021 microgram/person/day for Spanish people.

N-nitrosodimethylamine content of US and Canadian beers.

A total of 194 beers (148 US and 46 Canadian) were analysed for volatile N-nitrosamines. The sampling was designed to include different types of beers brewed from malts at all commercial-scale malt houses by the major beer manufacturers in both countries. N-Nitrosodimethylamine (NDMA), the only volatile N-nitrosamine detected, was found in 56% of the beers (detection level, 0.05 microgram/kg), at a mean level of 0.074 microgram/kg. The results indicate that NMDA levels in present-day US and Canadian beers are approximately 1-5% of what they were a decade ago.

Isolation and characterization of products from the nitrosation of the alkaloid gramine.

The nitrosation of gramine, a tertiary amine alkaloid present in barley malt, was carried out by reaction with sodium nitrite in buffered acetic acid (pH 3.4) for 1 hr at room temperature. Two major non-volatile products of the nitrosation reaction were isolated by preparative HPLC and characterized as indole-3-carboxylic acid and N1-nitroso-3-nitromethylindole. This interpretation was supported by spectral data. The nature of these products indicated that gramine did not undergo nitrosation by the expected mechanism of nitrosative dealkylation. A mechanism is offered to explain the labile nature of the dimethylamino group found in gramine.

Combination of a GC-TEA and a GC-MS-data system for the microgram/kg estimation and confirmation of volatile N-nitrosamines in foods.

An analytical procedure has been outlined in which volatile N-nitrosamines in foods are isolated by vacuum distillation, cleaned up, identified and quantified by GC-TEA and qualitatively confirmed by GC-MS, coupled with a data system. Spectra are presented which demonstrate that this technique is capable of confirming NDMA and NPYR in a variety of foods at levels of 1 to 10 micrograms/kg. Unequivocal confirmation is based on three types of evidence: (1) the compound is TEA positive; (2) the compound has the correct retention time on a packed and on a capillary column; (3) the complete mass spectrum closely matches standard spectra. These procedures have been used to confirm the presence of trace levels of NDMA in domestic beer and in non-fat dry milk.