International N-nitroso compounds check sample programme: report on the performance in the second study dedicated to...

The second check sample survey for the determination of N-nitrosamines in beer and malt has been initiated. Each laboratory received four samples: two beer, from the same batch, spiked respectively with 0.5 microgram/l N-nitrosodimethylamine (NDMA) and 4 micrograms/l NDMA plus 30 micrograms/l N-nitrosoproline (NPRO) and two naturally contaminated malts. Sixteen laboratories sent their results and two apologized in view of analytical problems. Results from this have been statistically evaluated. Comparison to those from the previous study demonstrated a distinct improvement in the results from the analysis of NDMA in beer and malt. Little has been achieved for the other two common contaminants of beer and malt, N-nitrosopyrrolidine (NPYR) and NPRO. For this latter compound in beer, however, some hope came from the data produced by the method of Sen et al. (1983), but the number of results is insufficient to allow firm conclusions to be drawn.