AUTOMATED IN-SITU GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC ANALYSIS OF PPT LEVEL VOLATILE ORGANIC TRACE GASES USING MULTISTAGE SOLID-ADSORBENT TRAPPING
AUTOMATED IN-SITU GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC ANALYSIS OF PPT LEVEL VOLATILE ORGANIC TRACE GASES USING MULTISTAGE SOLID-ADSORBENT TRAPPING
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DOI：
10.1016/0021-9673(94)80551-2
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发表时间：
1994-08-12
影响因子：
4.1
通讯作者：
GREENBERG, JP
中科院分区：
文献类型：
--
作者：
HELMIG, D;GREENBERG, JP
开发了一种全自动采样/注入系统，用于对对流层背景水平的挥发性有机化合物进行气相色谱-质谱（GC-MS）分析。最多 100 升空气样品中的有机痕量气体被捕获在温度控制的固体吸附剂捕集器中。该仪器采用单级采样/解吸入口系统，设计为封闭装置，在采样和分析之间不需要任何重新安装管道的步骤。为了进行分析，吸附剂捕集器被热解吸并反冲到色谱柱上，其中有机痕量气体被直接冷冻聚焦。测试的吸附剂为Carbotrap、Carbotrap C、Carbosieve S III、Tenax TA、Tenax GR 以及这些吸附剂的多级组合。通过在高于捕获和样品转移期间使用的温度下反冲吸附剂捕集器、切换阀和采样序列之间的转移管线，可以最大限度地减少空白和吸附剂伪影的干扰。可浓缩的高样品体积和低背景水平允许在 GC-MS（电子轰击电离扫描模式）中以约 100% 的最低水平进行结构鉴定。每个峰 100 pg（约 10-(12) mol）相当于万亿分之一 (v/v) 水平下的大气浓度。可以鉴定的有机化合物的挥发性范围大约是从戊烷到十五烷。该系统完全由计算机控制，可以全天候、无人值守地连续运行，进行现场分析。该仪器于1992年7月和8月在美国夏威夷莫纳罗亚天文台成功部署。
A fully automated sampling/injection system for the gas chromatographic-mass spectrometric (GC-MS) analysis of volatile organic compounds at tropospheric background levels was developed. Organic trace gases from air samples up to 100 l were trapped in temperature-controlled solid-adsorbent traps. The instrument utilized a one stage sampling/desorption inlet system designed as a closed device that did not require any replumbing steps between sampling and analysis. For analysis, the adsorbent trap was thermally desorbed and backflushed onto the chromatographic column where organic trace gases were directly cryofocused. Adsorbents tested were Carbotrap, Carbotrap C, Carbosieve S III, Tenax TA, Tenax GR and multistage combinations of these adsorbents. Interferences from blanks and adsorbent artifacts were minimized by backflushing the adsorbent trap, switching valve and transfer line between sampling sequences at temperatures above the levels used during trapping and sample transfer. The high sample volumes that could be concentrated and the low background levels allowed structural identification in GC-MS (electron impact ionization scan mode) at minimum levels of ca. 100 pg per peak (ca. 10-(12) mol) equivalent to atmospheric concentrations at the lower parts per trillion (v/v) level. The volatility range of organic compounds that could be identified was approximately from pentane to pentadecane. The system was completely computer controlled and could be operated continuously and unattended around the clock for in situ analysis. The instrument was successfully deployed at the Mauna Loa Observatory, Hawaii, USA in July and August 1992.