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Photolysis of volatile nitrosamines at the picogram level as an aid to confirmation



Photolysis of volatile nitrosamines at the picogram level as an aid to confirmation



Journal of Chromatography 140(3): 284-287



An average of 50% of the 7 NA [nitrosamines] disappeared within 10-15 min when a methylene chloride solution containing 0.5 ng/.mu.l of each NA was subjected to the experimental conditions for photolysis. After 60 min, none of the NA could be detected. This photolysis procedure was applied to samples derived from fried bacon. The chromatograms of the same sample unphotolyzed and following UV irradiation show 3 peaks of interest. The peak at 4.5 min is the MENA [methylethylnitrosamine] internal standard and is equivalent to 60% recovery of this NA. MENA is not normally found in fried bacon. The other peaks correspond to the retention times of dimethylnitrosamine (DMNA) and nitrosopyrrolidine (NPy). The concentration of the 2 NA is equivalent to 2 .mu.g/kg DMNA and 6 .mu.g/kg NPy with respect to the quantity of fried bacon used. After photolysis, the 3 peaks disappeared providing additional presumptive evidence of the presence of these NA. Under these conditions, 3 .mu.g/kg or greater of NA can be confirmed by MS [mass spectroscopy] with a high degree of reliability, except when the sample contains a large amount of interfering material that prevents the determination of the exact mass of the parent ion. In this particular sample, NPy could easily be confirmed by MS but the small amount of DMNA would make MS confirmation difficult without additional sample scale-up and clean-up. This method was successfully applied to the analysis of volatile NA in other food products and types of materials including fried bacon drippings, cured sausage, fish and cheese products, tobacco smoke condensate, deionized water, gastric contents and saliva. The same solutions must be transparant to UV light. The efficiency of denitrosation is adversely affected by the presence of highly colored material and suspended matter. The use of an added NA to obtain recovery data for the separation and isolation procedure is a good indicator to determine the completeness of the denitrosative degradation. Skewed shaped peaks having a retention time greater than NPy were occasionally observed in photolyzed but not in unphotolyzed fish samples. These peaks, probably secondary reaction products, do not significantly affect the utility of the photolysis procedure. Several samples that gave a TEA [tricthanolamine] response in the GLC region where volatile NA would be expected to elute were also found. These peaks did not disappear on photolysis, indicating that they were probably not due to NA. The identification of these compounds is currently under investigation.

Accession: 006110987

Download citation: RISBibTeXText

PMID: 914920

DOI: 10.1016/s0021-9673(00)93592-1

Download PDF Full Text: Photolysis of volatile nitrosamines at the picogram level as an aid to confirmation



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