Nahir TM, Morales KM
Department of Chemistry, California State University, Chico 95929-0210, USA.
Anal Chem. 2000 Oct 1;72(19):4667-70. doi: 10.1021/ac0004153.
The requirements for attaining constant holdup times in capillary gas chromatography (GC), while linearly programming both column temperature and inlet pressure, are illustrated. A scheme, which is based on a series of responses from isothermal and isobaric conditions, is proposed. The responses from two commonly used GC instruments, one with a mass-selective detector operating at near-vacuum pressure and another with a flame-ionization detector at ambient pressure, are analyzed. A significant deviation from Poiseuille flow is noted due to the use of helium as a carrier gas. Nonetheless, the experimental holdup times are approximately constant over a range of temperatures and pressures. Theoretical analysis reveals the spatial and temporal dependence of flow rates inside the column during the programmed runs.
阐述了在毛细管气相色谱（GC）中，在对柱温和进样口压力进行线性程序升温时，实现恒定保留时间的要求。提出了一种基于等温等压条件下一系列响应的方案。分析了两种常用气相色谱仪的响应，一种配有在近真空压力下运行的质量选择检测器，另一种配有在常压下运行的火焰离子化检测器。由于使用氦气作为载气，发现与泊肃叶流存在显著偏差。尽管如此，在一定温度和压力范围内，实验保留时间大致恒定。理论分析揭示了程序升温运行期间柱内流速的空间和时间依赖性。
