The retention time of each NAm was identified from their characteristic ion: 6.2, 7.3, 12.7 and 9.9 min respectively for the NDMA, NDEA, NDBA and NPIP. The spectra were analyzed with the NUST/
EPA/NIH mass spectral library. In order to identify the NAms in the wine samples, two criteria were considered: the first was the addition of NAm standard solution to the red wine matrices containing the NAm to be studied; it was observed that the corresponding NAm signal increased as the standard was added, see Fig. 3.