Volatile N-nitrosamines in gastric juice of patients with various conditions of the gastrointestinal tract determined by gas chromatography–mass spectrometry and related to intragastric pH and nitrate and nitrite levels
Introduction
During the past 2 decades various studies 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22and reviews 23, 24, 25, 26, 27, 28, 29, 30, 31concerning the endogenous formation of N-nitroso compounds (NOC) in gastric juice in relation to gastric carcinogenesis have been published. In most of these studies, apparent total N-nitroso compounds were determined by chemical denitrosation to form NO and thermal energy analysis (TEA) 1, 2, 3, 4, 5. These data have been related to gastric pathology 5, 6, 7, 9, gastric nitrate and nitrite concentrations 4, 5, 6, 7, 8, 22, pH 3, 4, 5, 6, 7, 8, 12, bacterial overgrowth 6, 7, 10, 11, medication 3, 8, 9, 10, 32and salivary [33]and urinary nitrate, nitrite and NOC concentrations 12, 13, 14, 34. Other papers describe the nitrosation of specific amino compounds, such as proline, as a model for endogenous nitrosation 15, 16, 17, 18, 30, 35or the inhibition of such reactions by scavengers 22, 23, 36, 37, e.g. ascorbic acid. Epidemiological research in gastric cancer has recently been reviewed [24], with emphasis on the role of nitrate burden and endogenous nitrosation reactions.
The availability of capillary gas chromatography in combination with high sensitivity and when necessary, high resolution mass spectrometry, enables the accurate and sensitive detection and determination of individual volatile N-nitrosamines (NAms) [38]. Correlation of the concentration of NAms in the gastric juice of subjects with various clinical conditions of the gastrointestinal tract with other intragastric parameters and with medical history might provide an insight into the formation of individual NAms as well as into their clinical relevance. Therefore, we screened the volatile NAm content of the gastric juice of 71 patients and compared the results with gastric pH and with nitrate and nitrite levels in saliva and gastric juice.
Section snippets
Patients
Gastric juice samples were obtained endoscopically from 71 patients with various upper abdominal complaints who visited the Endoscopy Department of the University Hospital Maastricht. Saliva samples (n=40) were also collected at the same time from some of these patients. At the time the gastric juice and saliva samples were collected, the patients had fasted for at least 12 h. For men (n=39) and women (n=32) the mean age was 56 years (range 27–85 years) and 55 years (range 17–85 years),
Results and discussion
The concentrations of the individual NAms in the gastric juice samples were determined and mean values are given in Table 1. The main volatile NAm detected in gastric juice appeared to be NDEA, which represented approximately 70% of the total volatile NAms found. No influence of sex and age on the individual and total volatile NAm content and on gastric juice pH could be detected.
The mean nitrate and nitrite concentrations in saliva and in gastric juice are given in Table 2. The concentrations
Conclusions
Capillary GC-MS proved to be a useful tool for the detection and quantitation of individual volatile NAms in gastric juice. High resolution mass spectrometry was used to confirm the elemental composition of the compounds detected. In combination with the retention time of these compounds, this enables a reliable determination of their identity. The levels of the individual NAm contents appear to be subject to a rather strong interindividual variance. Nevertheless, the data for volatile NAms
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2022, Food ControlCitation Excerpt :NAs are divided into volatile NAs and non-volatile NAs, and currently more studies were focused on volatile NAs. Commonly used methods to measure NAs mainly include UV-spectrophotometry, HPLC, LC-MS (Asami, Oya, & Kosaka, 2009; Ripollés, Pitarch, Sancho, López, & Hernández, 2011), GC (Campillo, Viñas, Martínez-Castillo, & Hernández-Córdoba, 2011) and GC-MS (Dallinga et al., 1998). HPLC combined with different detectors such as ultraviolet (UV), electronic capture device (ECD), etc. are widely used for the detection of nitrosamines (Crews, 2010; Mcday, 2010), but in the literature, HPLC is mostly applied to the detection of nitrosamines in water, and it is rarely applied to meat products (Asami et al., 2009), LC-MS/MS has been applied in recent years because of its excellent signal-to-noise ratio and selectivity, but the determination of NAs by HPLC involves the decomposition of these substances into amines and nitroso ions by chemical or optical reactions, followed by the derivatization and then detection by different detectors (Asami et al., 2009).
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2016, Journal of Pharmaceutical and Biomedical AnalysisCitation Excerpt :NMOR was found in 16 gastritis, 18 ulcer, and 22 gastric cancer samples at quantities up to 46.4, 47.1, and 1844.7 pg/mL, respectively. N-Nitrosodimethylamine (NDMA), suspected to have carcinogenic potential, the most frequently occurring nitrosamine in foods and can also be formed endogenously in the stomach [13,15], was detected in 67 of the 72 gastric juice samples at highest concentrations to be up to 386.3 pg/mL in gastric cancer, 87.6 pg/mL in ulcer and 59.9 in gastritis groups. These findings are supported by literature [24].
Chapter 1 Gas chromatographic analysis of environmental amines with selective detectors
2001, Handbook of Analytical SeparationsOccurrence and significance of gastric colonization during acid-inhibitory therapy
2001, Best Practice and Research: Clinical GastroenterologyIntragastric volatile N-nitrosamines, nitrite, pH, and Helicobacter pylori during long-term treatment with omeprazole
2001, GastroenterologyCitation Excerpt :In the last 2 decades, several research groups developed methods to measure total NOC as a group in biological fluids applying a thermal energy analyzer (TEA).35,36 In the present study, we have measured individual volatile N-nitrosamines in gastric juice and urine with high-resolution gas chromatography-mass spectrometry, a sensitive and specific method routinely applied in our laboratory.31,37,38 This method has the advantage of measuring individual NOC, based on the gas chromatography retention time and the elemental composition of the detected ions.