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When a peak was observed at the retention time of one of the 14 nitrosamines, the identity
of this compound was confirmed by mass spectrometry (MS). To ensure adequate cleanup
for this analysis, the concentrated methylene chloride eluate from the silica gel column was
passed through an acid-Celite column.
The identities of the nitrosamines isolated were confirmed with a combined GLC-MS
system. A Varian Model 5600X, 2-stage membrane separator was interfaced to an Atlas
CH-4 mass spectrometer. The separator is an integral part of the Varian Model 1700 gas
chromatograph. This unit has the facility of venting the solvent to the atmosphere and
maintaining the MS vacuum. Accordingly, large quantities of solvent can be injected onto
the GLC column, vented, and prevented from entering the mass spectrometer. In this study,
30 /A of the final methylene chloride extract (equivalent to 100 ng nitrosamine) was injected
onto the GLC column.
RESULTS AND DISCUSSION
Before the recovery studies, the individual food products were analyzed for the 14 volatile
N-nitrosamines. In instances where a nitrosamine was suspected, recovery values were ad
justed appropriately. As shown in Table 1, recoveries of the 14 volatile N-nitrosamines
added at 10 ppb (/µg/kg) to 25 g of the food products ranged from 67 to 100%, with an
overall average of 84%.
A total of 121 food samples were analyzed during this survey, including bacon, lard, baby
food, total diet samples, miscellaneous pork products, spice-cure mixtures, imported
cheeses, and Icelandic national foods.
Table 1. Recoveries of nitrosamines a added at levels of 10 ppb to 25 g food product
Rec., %
Sample Product Range Av.
1 Bacon, hams, other pork
products (liver) 77-95 82
2 Baby foods 76-95 83
3 Cheeses (imported) 71-94 85
4 Fats and oils 67-100 83
5 Total diet products 75-100 86
6 Spice-cure mixtures 74-87 81
7 Icelandic foods 84-100 91
a 14 volatile A/-nitrosamines as described in text.
All bacon samples were purchased at local retail markets. Bacon was analyzed raw and also
after frying at 340 °F in an electric frypan for 3 min on each side. Excess fat was removed
from the bacon by blotting with paper toweling. As shown in Table 2, N-nitrosopyrrolidine
was found in fried bacon at levels ranging from 7 to 139 ppb.
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