摘要
由于受大气中Ｏ２、Ｈ２Ｏ和氯氟烃的干扰，大气中的Ｎ２Ｏ难于用简单的气相色谱法连续观测。实验中对带有电子捕获检测器的气相色谱仪（Ｇ－ＥＣＤ）进行了改进，系统中安装了１０通进样反吹阀和４通切换阀，色谱系统中同时采用两根ＰｏｒａＰａｋＱ填充柱，并在进样系统中安装了水蒸汽和ＣＯ２过滤吸收器。这样，干扰物不进入检测器，对Ｎ２Ｏ信号没有干扰，从而提高了Ｎ２Ｏ分析灵敏度和精确度。从１９９２年１１月起，我们开始对北京大气Ｎ２Ｏ浓度进行长期定位测检。用这种方法测得的北京大气Ｎ２Ｏ月平均浓度介于３０１±９．８ｐｐｂｖ至３３５±２２．５ｐｐｂｖ之间，平均值为３１７±１２．８ｐｐｂｖ。
It is very difficult to analyze atmospheric nitrous oxied with common gas chromatograph (GC) because of its low concentration and the interference of O2, H2O and chloro-Fluoro-hydrocarbons. Therefore, a GC equipped with an electron capture detector (ECD) was modified for N2O measurement. A 10-port valve for sampling and back flushing as well as a 4-port switching valve was incorporated into the GC System while a precoloum was used in combination with an analytical column. In addition, two absorbent traps were equipped in the inlet system to filter off H2O and CO2. In the proiect caried out in Beijing, China since November 1992 to monitor atmospheric nitrous oxide, the concentration of atmospheric N2O in Beijing was analyaed with this modified system to be 317±12.8ppbv.
出处
《分析测试技术与仪器》
1994年第2期19-24,共6页
Analysis and Testing Technology and Instruments
基金
边界层物理与大气化学国家重点实验室的一个长期观测项目
