Pignatelli B, Richard I, Bourgade M C, Bartsch H
International Agency for Research on Cancer, Lyon, France.
IARC Sci Publ. 1987(84):209-15.
An improved procedure for the analysis of total N-nitroso compounds (NOC) in human gastric juice was developed by modifying previous methods. The gastric juice sample, treated with sulfamic acid to remove nitrite, is injected directly into refluxing ethyl acetate containing either acetic acid for determining thermo/acetic acid-labile-thermal energy analyser (TEA)-responsive compounds (TAC), or into hydrogen bromide for the analysis of TAC and NOC. The nitric oxide (NO) levels released are measured by chemiluminescence by TEA, and the difference between the two determinations represents the concentrations of NOC in gastric juice. This method also allows the determination of nitrite and is not affected by nitrate concentrations up to 1,000 mumol/l. The method was found to be reproducible and sensitive (detection limit, 0.02 mumol NOC/l), requiring only small volumes of gastric juice and no prior extraction. Because the difficulties arising from the 'system response' to the denitrosating agent and variability of NO release by acetic acid from nitrite were eliminated, this improved method can more accurately distinguish NOC from most other TEA-responsive species. Suitable techniques for stabilizing gastric juice samples from duodenal ulcer/atrophic gastritis patients and the influence of the time and storage conditions on NOC concentrations have been studied.
通过改进先前的方法，开发出了一种用于分析人胃液中总N-亚硝基化合物（NOC）的改进程序。用氨基磺酸处理以去除亚硝酸盐的胃液样品，直接注入含有乙酸的回流乙酸乙酯中以测定热/乙酸不稳定的热能分析仪（TEA）响应性化合物（TAC），或注入溴化氢中以分析TAC和NOC。释放的一氧化氮（NO）水平通过TEA的化学发光法测量，两次测定之间的差异代表胃液中NOC的浓度。该方法还可以测定亚硝酸盐，并且不受高达1000μmol/l硝酸盐浓度的影响。该方法具有可重复性和灵敏性（检测限为0.02μmol NOC/l），只需要少量胃液且无需预先提取。由于消除了“系统对脱亚硝化剂的响应”以及乙酸从亚硝酸盐中释放NO的变异性所带来的困难，这种改进的方法能够更准确地将NOC与大多数其他TEA响应性物质区分开来。已经研究了稳定十二指肠溃疡/萎缩性胃炎患者胃液样品的合适技术以及时间和储存条件对NOC浓度的影响。
