O-Nitrosamines

All of these results support the o-hydroxylation hypothesis, but they do not prove it. No o-hydroxy nitrosamine or a derivative of one has ever been isolated as a metabolite of any nitrosamine. Nevertheless, a-hydroxylation is an attractive working hypothesis and it seems to account for... 

Although the o-hydroxylation hypothesis has been given considerable support, it is clear that nitrosamines with alkyl side chains longer than methyl present additional possibilities for biological activation. It was stated earlier that even the o-hydroxylation hypothesis is based on considerable circumstantial evidence. This means that the other possible pathways are even more speculative, and hence, much more research needs to be carried out before some of the ideas advanced below will gain acceptance, or be put to rest. 

Other possible mechanisms have been considered O), but they either predict formation of products which are not observed, do not explain the observed O3/UDMH stoichiometry, or are inconsistent with the results of the UDMH-NO stoichiometry and the formation of nitrosamine and H2O2 in this system. The other products observed, and the fact that the nitrosamine and H2O2 yields are somewhat less than the predicted 100% and 50% of the UDMH consumed, can be attributed to possible secondary reactions of the nitrosamine with the OH radical. 

Hickman, D.H. Hardwick, W.A. Ladish, W.J. Meilgaard, M.C. Jangaard, N.O. "Technical Report of the United States Brewers Association Ad Hoc Committee on Nitrosamines Master Brewers Association of America, Technical Quart. In press (1981). Scanlan, R.A. O Brien, T.J. Unpublished data. 

The first step in the analysis is extraction of the tobacco with buffer solution (pH 4.5) containing 20 mM ascorbic acid. The nitrosamines are then concentrated by partition with dichloromethane, and a chromatographic clean-up on alumina. In the final step, the concentrate is analyzed by GC-TEA and confirmation of the nitrosamines is obtained by GC-MS (O. If isolated amounts of the nitrosamines are below levels needed for GC-MS confirmation, we employ confirmatory techniques proposed by Krull et a. ( 5). 

The massive contamination of NDE1A in alkaline synthetic fluids (3%) found by Fan et al Q) cannot be explained by known nitrosation kinetics of di- or triethanolamine. Instead, more powerful nitrosation routes, possibly involving nitrogen oxide (N0X) derivatives (e.g., N02> N O t) may be responsible for the amounts of NDE1A in these products (34). In fact, a nitrite-free commercial concentrate was shown to accumulate NDE1A up to about 10 0 days at which time the levels dropped dramatically (19). Inhibition of N0X contaminants may be an effective route to the inhibition of nitrosamine formation in metalworking fluids. 

Bradley, M.O., Dysart, G., Fitzsimmons, K., Harback, P., Lewin, J. and Wolf, G. (1982). Measurement hy filter elution of DNA single- and double-strand breaks in rat hepatocytes Effects of nitrosamines and y-irradiation. Cancer Res. 42 2569-2597. 

A method involving SPE was developed for the determination of ten A-nitroso amino acids in cured meat products. These compounds were derivatized with diazomethane followed by O-acylation of hydroxyl groups with acetic anhydride-pyridine reagent. The methyl esters and their acylated derivatives were separated by GC on a DB-5 fused silica capillary column and quantified with a TEA-CLD specific for the nitric oxide derived from the thermal denitrosation of nitrosamines recovery exceeded 75% at the 10 ppb level579. 

DIPT, see Isopropyl ether Dipentyl, see Decane Diphenyl, see Biphenyl 1,1 -Diphenyl, see Biphenyl 4,4 -Diphenylenediamine, see Benzidine p,p -Diphenylenediamine, see Benzidine Diphenylenemethane, see Fluorene o-Diphenylenemethane, see Fluorene Diphenylene oxide, see Dibenzofuran Diphenyl ether, see Phenyl ether s/m-Diphenylhydrazine, see 1,2-Diphenylhydrazine lV,A/ -Diphenylhydrazine, see 1,2-Diphenylhydrazine Diphenylnitrosamine, see IV-Nitrosodiphenylamine Diphenyl-lV-nitrosamine, see IV-Nitrosodiphenylamine A,lV-Diphenylnitrosamine, see IV-Nitrosodiphenylamine A,Al-Diphenyl-lV-nitrosamine, see IV-Nitrosodiphenylamine Diphenyl oxide, see Phenyl ether Diphenyltrichloroethane, see p,p -DDT Diphosphoric acid, tetraethyl ester, see Tetraethyl pyrophosphate... 

Planas C, Palacios O, Ventura F, Rivera J, Caixach J (2008) Analysis of nitrosamines in water by automated SPE and isotope dilution GC/HRMS - Occurrence in the different steps of a drinking water treatment plant, and in chlorinated samples from a reservoir and a sewage treatment plant effluent. Talanta 76 906-913... 

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