Grall A J, Zellers E T, Sacks R D
Department of Chemistry, University of Michigan, Ann Arbor 48109, USA.
Environ Sci Technol. 2001 Jan 1;35(1):163-9. doi: 10.1021/es001255f.
A pressure-tunable, series-coupled column ensemble was used with atmospheric pressure air as carrier gas for the vacuum-outlet GC analysis of 42 volatile and semivolatile organic compounds commonly encountered as indoor air pollutants. Separation strategies applicable to a field-portable instrument that will employ a dual-stage preconcentrator and a microsensor array as the detector were developed, where coelution of certain analytes can be tolerated. The capillary column ensemble consists of a 4.5-m segment of nonpolar dimethyl polysiloxane followed by a 7.5-m segment of polar trifluoropropylmethyl polysiloxane. Good long-term thermal stability of the column ensemble was observed for continuous operation in air at temperatures up to 210 degrees C. A computer-driven pressure controller at the column junction point is used to adjust vapor retention for specified sets of target compounds. The compounds were divided into two groups according to retention order, and high-speed analysis conditions were determined for the two groups individually as well as for the entire mixture. The earlier eluting group of 21 compounds was analyzed isothermally at 30 degrees C in about 160 s using a single, on-the-fly junction-point pressure change during the separation. The later eluting group of 21 compounds was analyzed in about 200 s with temperature programming and a constant (tuned) junction-point pressure. The entire mixture was analyzed in about 400 s using a two-step temperature program and a three-step pressure program, with minimal overlap in eluting peaks. Separations are adequate for analysis by a sensor array capable of discriminating among small groups of coeluting vapors on the basis of their response patterns.
使用了一种压力可调的串联柱组件，以常压空气作为载气，用于对42种常见的室内空气污染物挥发性和半挥发性有机化合物进行真空出口气相色谱分析。开发了适用于现场便携式仪器的分离策略，该仪器将采用双级预浓缩器和微传感器阵列作为检测器，在这种情况下某些分析物的共洗脱是可以容忍的。毛细管柱组件由一段4.5米长的非极性二甲基聚硅氧烷和一段7.5米长的极性三氟丙基甲基聚硅氧烷组成。在高达210摄氏度的空气中连续运行时，观察到柱组件具有良好的长期热稳定性。在柱连接点处使用计算机驱动的压力控制器来调整特定目标化合物组的蒸汽保留时间。根据保留顺序将化合物分为两组，并分别确定了两组以及整个混合物的高速分析条件。较早洗脱的21种化合物的组在30摄氏度下等温分析，大约160秒完成，在分离过程中使用单次即时连接点压力变化。较晚洗脱的21种化合物的组在大约200秒内通过程序升温以及恒定（调整）的连接点压力进行分析。整个混合物在大约400秒内使用两步程序升温以及三步压力程序进行分析，洗脱峰的重叠最小。这些分离对于能够根据响应模式区分少量共洗脱蒸汽组的传感器阵列分析来说是足够的。
