FID/TCD并联气相色谱法测定天然气水合物的气体组成

摘要

A gas chromatographic analysis technique with parallel detectors of flame ionization detector and thermal conductivity detector( GC - FID/TCD) was established. The method can be used to determine 16 gases(C1 - C6 alkanes, C02, H2S, 02 +N2) of natural gas hydrates simultaneously by one injection. The analysis parameters, such as capillary column, temperature program, column flow, inlet temperature, detector temperature, the reference and makeup flow of TCD were optimized. Under the optimal conditions, good linearities were obtained in the experimental concentration range for the 16 gases with correlation coefficients (r2) of 0.999 03 - 0. 999 98. The limits of detection ranged from 0.000 3 mol/mol to 0. 046 mol/mol with relative standard deviations (RSDs, n =6) of 1. 6% -5.0% . The method was successfully applied in the determinations of gas compositions in the natural gas hydrates from Qilian Mountain Permafrost, South China Sea and laboratory synthetic samples. The result showed that the method was simple, practical, sensitive and reliable, and was suitable for the determination of gases in natural gas hydrates.%建立了一种氢火焰离子化检测器(FID)与热导检测器(TCD)并联检测的气相色谱分析技术.该方法一次进样,即可实现天然气水合物中C1～C6、CO2、H2S、O2+ N2 16种气体成分的同时测定.实验优化了色谱柱、升温程序、柱流速、进样口温度、检测器温度、TCD参考气和尾吹气流速等仪器分析参数.在优化条件下,16种气体分子在实验浓度范围内线性关系良好,r2为0.999 03～0.999 98,方法检出限为0.0003～ 0.046 mol/mol,相对标准偏差(n=6)为1.6％～5.0％.对祁连山冻土区、南海神狐海域、人工合成水合物样品的分析表明,该方法简便实用、灵敏可靠,可满足天然气水合物气体组成的分析要求.