Recent studies in Canada on the analysis and occurrence of volatile and non-volatile N-nitroso compounds in foods.

The present paper briefly summarizes the research activities of the Food Research Laboratories, Canadian Health Protection Branch, during the past two years. Data presented indicate that traces of nitrosamines, mainly nitrosodimethylamine and nitrosodiethylamine, can occur in cheese. Several new analytical methods are presented for the determination of non-volatile nitroso compounds, such as nitrosohydroxypyrrolidine, nitrosodiethanolamine, nitrosoproline, nitrosohydroxyproline and nitrosoglyphosphate (a nitrosated herbicide). It is shown that all of the above compounds, even the very polar nitrosoglyphosphate, can be converted to volatile derivatives and then analysed by GLC-MS or by conventional GLC using a specific (such as P-photometric) detector. Traces of nitrosohydroxypyrrolidine have been detected in a few samples of cooked bacon. Contrary to previously reported findings, no significant levels of nitrosoproline were detected in the 6 samples of raw bacon analysed.