Nitrosamines table

Obviously, this property finds interesting applications in stereochemical determinations involving oximes (Tables 7.23 - 7.25), cyclic amines (Table 7.1), tetrahydro-1,3-oxazines (Table 7.1), nitrosamines (Table 7.31) or alkyl nitrites (Table 7.32) for example (G 21) (J 2)... 

The spectroscopic properties of the /V-nitrosamines, especially the nmr and mass spectra, vary widely depending on the substituents on the amine nitrogen (44—47). The nmr spectra are affected by the E—Z isomerism around the N—N partial double bond and by the axial—equatorial geometry resulting from conformational isomerism in the heterocycles (44,45). Some general spectral characteristics for typical dialkylnitrosamines and simple heterocycHc nitrosamines are given in Table 1. 

Table 2. Toxicological Properties of Some Representative A Nitrosamines in the BD Rat ...

The efficient recovery of volatile nitrosamines from frankfurters, followed by gc with chemiluminescence detection, has been described (133). Recoveries ranged from 84.3 to 104.8% for samples spiked at the 20 ppb level. Methods for herbicide residues and other contaminants that may also relate to food have been discussed. Inorganic elements in food can be deterrnined by atomic absorption (AA) methods. These methods have been extensively reviewed. Table 8 Hsts methods for the analysis of elements in foods (134). 

A Structure-Selectivity Model. Nitrosamines are usually highly sensitive towards one or a few target organs some examples are listed in Table III. A casual examination of the structures... 

The experimental conditions and products observed at selected times in the UDMH + O3 experiments are shown in Table I. In general, the nitrosamine yields ranged from -60% when the reaction was carried out in a slight excess of UDMH to -100% when O3 was in excess. The HCHO, H2O2, and HONO yields were -13%,... 

Irradiation of the UDMH + Oq Reaction Products. One experiment was conducted in which the UDMH + O3 reaction products (with UDMH in slight excess) were irradiated by sunlight. The results are shown in Table I and Figure 1. It can be seen that rapid consumption of UDMH, the nitrosamine, and HONO occurred, with N-nitrodimethylamine (also dimethyInitramine) and additional formaldehyde being formed. The formation of nitramine upon irradiation of the nitrosamine is consistent with results of previous studies in our laboratories (9,10), and probably occurs as shown ... 

The formation of the other products observed during the irradiation can be attributed to secondary reactions. For example, formation of N2O, HCHO, and traces of CH3ONO2 (Table II) may result from the reaction of the nitrosamine with OH ... 

Almost any class of reduced nitrogen compound can serve as the nitrosatable precursor of an N-nitroso compound. To make matters worse, every nitrogen coordination state from primary to quaternary has been converted to a nitrosamine. A glance at the list of some of the known nitrosatable substrates given in Table II illustrates what a wide variety of N-nitroso compounds analysts might expect to encounter in our complex environment. 

Table III shows that any of the higher oxidation states of nitrogen can serve as a nitrosating agent. To form a nitrosamine, all that need happen is for a nitrosating agent to encounter a nitrosatable substrate under favorable conditions, which might (but need not) involve acceleration of the reaction rate by one of the chemical or physical agents indicated in Table IV.

Decomposition studies confirmed that N-nitrosamides are much less stable than volatile N-nitrosamines such as NPYR and NDMA (79). Thermal studies utilizing heating conditions commonly encountered in the cooking of bacon and pork roasts indicated that N nitrosomethylpropionamide (NOMP) was degraded to the extent of 74-97% compared to 3-14% for NPYR and NDMA (Table V). It was tentatively concluded that the major... 

An attempt to estimate human daily impact of N nitroso compounds is shown in Table I. The apparent intake from food of preformed nitrosamines is comparatively low, at least in these surveys of a Western diet in England (3). The Intake directly to the respiratory tract from smoking could be somewhat larger. However, if the blood levels reported are confirmed as correct, then inputs of up to 700 meg per day of at least N nitrosodimethylamine (NDMA) may be calculated, based on pharmacokinetic considerations of data obtained in animals and extrapolated to man. It should be emphasized that no information is available at present on nitrosamide intake or in vivo formation, largely because of analytical limitations. 

The most important sources of preformed environmental nitrosamines according to present knowledge, are given in Table I. 

Since the first report of N-nitrosodimethylamine (NDMA) contamination in beer (ij ), there have been a number of surveys on volatile nitrosamine occurrence in beers of different types and origins. The data in Table I includes NDMA analyses on light beers, dark beers, ales, and malt liquors. Table I shows that the... 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

In Smoke. We compared the gas chromatograms of nitrosamines in matching aliquots of mainstream smoke derived from Burley type cigarettes that were identical except for the degree of nitrate fertilization during cultivation (Figure 2). This comparison supports the concept that the nitrate concentration in tobacco is a determining factor for the nitrosamine yields in the smoke. The data in Table II confirm this concept. These studies have... 

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)>... 

The persistence of the N-nitrosamine that may be formed in soil will depend on a host of conditions, such as soil type, organic matter content, clay content, pH, the microflora present in the soil, moisture content and temperature, etc. Superimposed on all these factors will be the chemical nature of the pesticide. The N-nitrosoatrazine ( ) formed in soil from the herbicide atrazine ( ) was shown to be rapidly disappeared (1). Thus, in soil W-nitrosoatrazine was observed after one week, but was absent 4 and 10 weeks later (Table IV). In contrast, N-nitroso-butralin (11 ) persisted much longer than N-nitrosoatrazine (9) under the same conditions (Table V) and was still detectable after 6 months (3). Our studies demonstrated that N-nitrosoglyphosate is persistent in the soil. Fox soil treated with 20 ppm of nitrite nitrogen and 740 ppm glyphosate contained about 7 ppm of N-nitrosoglyphosate even after 140 days (6). 

Perfluoroalkane-225 (PGR, Gainesville, FL) was admitted through a glass inlet system to provide reference peaks. Analytical and reference peaks for the nitrosamines studied are shown in Table I. Sample and reference peaks were scanned alternately at a repetition rate of approximately 1 sec and were monitored on an oscilloscope. When the nitrosamine peak appeared, the oscillographic recorder chart drive was engaged and remained on until the peak disappeared. Nitrosamine quantities were estimated by comparing the sum of sample peak heights measured from the chart (usually 10 to 20 values) with values derived from injection of standard solutions. 

Table I. Mass Spectral Peaks Employed for Identification of Nitrosamines...

Table II. Distribution Ratios of Some Volatile Nitrosamines...

Determination of Hydroxy-Nitrosamines. The column extraction procedure has proven flexible and convenient for isolating NDELA and BHP from a variety of matrices. No artifactual formation of these nitrosamines has been observed when sulfamic acid was incorporated with the sample. Addition of excess acid prevents elution of amines from the Celite column, minimizing nitrosation reactions at later stages. The triisopro-panolamine sample examined contained approximately 250 mg/kg BHP (Table IV). 

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