Nonvolatile nitrosamines

By using modem production methods it is possible to reduce the amounts of 1,4-dioxane to a level that is barely detectable with the best current analytical methods. Free ethylene oxide is now below detectable levels. Furthermore, volatile and nonvolatile nitrosamines ( NDELA ) both seem to be below detection limits of ppb in the alkanolamide-based sulfosuccinates. A good overview of modern analytical methods for the detection of 1,4-dioxane and ethylene oxide as well as nitrosamines and formaldehyde is given in Ref. 60. 

Nonvolatile Nitrosamines In Tobacco. A method which we developed several years ago for the analysis of tobacco-specific nitrosamines (TSNA 31) involves extraction of tobacco with buffered ascorbic acid TpH 4.5) followed by partition with ethyl acetate, chromatographic clean-up on silica gel, and analysis by HPLC-TEA (Figure 9). Results obtained with this method for a large spectrum of tobacco products (Table IV), strongly support the concept that the levels of nitrate and alkaloids, and especially the methods for curing and fermentation, determine the yields of TSNA in tobacco products. Recent and as yet preliminary data from snuff analyses indicate that aerobic bacteria play a role in the formation of TSNA during air curing and fermentation. 

Nonvolatile Nitrosamines In Saliva. In vitro experiments had indicated that the tobacco-specific nitrosamines are formed also during snuff dipping (26). Therefore, we analyzed the saliva of snuff dippers and tobacco chewers. A comparison of the results demonstrated the presence of TSNA in saliva at a wide range of concentrations (Table Vl), which could be ascribed to differences in the product, but also to differences in the manner of chewing, and, lastly, to individual factors in each person s saliva. 

Nonvolatile Nitrosamines In Tobacco Smoke. Although there are more than 10 million exsmokers in the U.S.A., 53 million adults continue to smoke cigarettes and an additional 10 million still smoke cigars or pipes (39). The cigarette smokers are exposed to about 10 ng of volatile nitrosamines, 20-40 ng of NDELA and, most importantly, to 1-10 pg of tobacco specific N-nitros-amines with each cigarette smoked (Table IV). Similar quantities of the TSNA are found in sidestream smoke. The quantities of TSNA in the smoke are dependent on nitrate, nitrite, tobacco alkaloids and on NNN, NNK and NAT in the tobacco itself (31)>... 

Various nonvolatile nitrosamines were analyzed using HPLC-UV photolysis-CLD. This was applied for determination of V-nitrosamides in dried squid589 and N-nitrosodiphenylamine (278c) in treated apples590. 

An improved HPLC-photohydrolysis-colorimetry method was validated for twenty-eight reference nitrosamines. These were separated by HPLC and photolytically cleaved by UV radiation. The resulting nitric oxide was oxidized and hydrolyzed to nitrite ions, which were derivatized into an azo dye with Griess reagent and measured spectrophoto-metrically. The method was applied to separate and detect hitherto unknown nonvolatile nitrosamines in biological fluids and food extracts591. 

Sen NP, Tessier L, Seaman SW, et al. 1985a. Volatile and nonvolatile nitrosamines in fish and the effect of deliberate nitrosation under simulated gastric conditions. J Agric Food Chem 33 264-268. 

Nitrosamines are derived from amines, and like aU Af-nitroso compounds, they have the N-N=0 functional group. They can be classified as volatile and nonvolatile. Volatile nitrosamines, in contrast to nonvolatile nitrosamines, can be removed from the matrix by distillation techniques and can be analyzed by gas chromatography (GC) without prior chemical derivatization. Alkyl and cyclic nitrosamines, which are volatile, have been intensively studied. The most commonly encountered nonvolatile nitrosamines are aryl compounds, hydroxylated compounds, and V-nitrosated amino acids. The structures of several nitrosamines are shown in Figure 12.1. 

Derivatization of A-nitrosamines can be employed not only to convert nonvolatile nitrosamines into volatile materials suitable for GC analysis, but also to improve selectivity and sensitivity, and to reduce the analysis time. The commonly used derivatization reactions for GC analysis of nitrosamines are stated below. 

Different chromatographic columns, including packed and capillary columns, have been used to separate volatile nitrosamines or nonvolatile nitrosamines after derivatization. 

GC coupled to TEA detection is the most suitable analytical method to determine volatile nitrosamines. However, a large number of A/-nitrosamines are not generally adequate for direct analysis by GC, either because of low volatility or thermal instability. In these cases, HPLC seems to be the method of choice for the analysis of volatile and nonvolatile nitrosamines. The correct choice of stationary phase and type of composition of the mobile phase depends on the detection method used. 

The development in the determination of many classes of nonvolatile nitrosamines depends on the development of detectors suitable for the trace analysis of ionizable, ionic, macromolecular, and thermally unstable A-nitroso compounds. In particular, the development of detectors compatible with reversed-phase liquid chromatographic conditions is receiving special attention. Among others, the electrochemical detectors are attractive because of their high sensitivity and their ability to operate in different aqueous and mixed aqueous-organic eluents. 

Some interesting classes of nitrosamines are decomposable by warm strong acids or by photolytic cleavage in alkaline media so that nitrite or nitrous acid is produced. They can be electrochemically detected as such or after further reaction. The availability of a voltametric detector for flowing solutions equipped with solid electrodes allows the direct anodic detection of the NO2 species produced by postcolumn photolysis. The Ce(IV) and iodide in acid medium have been investigated as postcolumn reagents for the oxidation and voltametric detection of the nitrite produced by the warm acid decomposition of nonvolatile nitrosamines. 

A152. Sen, N.P., S. Seaman, and M. McPherson Further studies on the occurrence of volatile and nonvolatile nitrosamines in foods in A-Nitroso compounds Analysis, 26A169. formation and occurrence, edited by E.A. Walker, L. 

Figure 7. Procedure for screening and identifying nonvolatile nitrosamines on LC-TEA showing the different solvent systems used (40)...

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