Thurbide Kevin B, Cooke Brad W, Aue Walter A
Department of Chemistry, University of Calgary, 2500 University Drive N. W., Calgary, Alta., T2N 1N4 Canada.
J Chromatogr A. 2004 Mar 12;1029(1-2):193-203. doi: 10.1016/j.chroma.2003.12.020.
A novel analytical device has been developed for gas chromatography. It is based on optical emission from a counter-current (i.e. counter-flowing) air or oxygen flame, which burns in an opposing stream of hydrogen and column effluent. The flame is typically positioned "upside down" on the upper (air) jet, which faces the lower (hydrogen + effluent) jet. It can also be positioned on the lower jet, be connected to both jets, or be suspended in the gap between them. Excellent stability can be obtained in any of these modes. Overall, this new "counter-current flame photometric detector" (ccFPD) responds to analytes in the manner of a conventional flame photometric detector (FPD); however, it can be operated over a much wider range of gas flows. For instance, the same physical ccFPD burner easily supports stable flames of air flows between 5 and 200 ml/min and corresponding hydrogen flows between 5 and 10,000 ml/min. Visual observation of the counter-current flame, in the presence of sulfur and phosphorus as test analytes, reveals intense, steady luminescence under a wide variety of conditions. Additionally, and in contrast to the commercial FPD, flame conductivity signals can be obtained that are similar in quality to those produced by a conventional flame ionization detector (FID). Thus the ccFPD is a flexible, easily optimized photometric detector. The exceptional flow stability of the ccFPD was used to explore the earlier reported phenomenon of strong signal/noise (S/N) ratios, which had been obtained for hetero-elements of the iron group from a conventional FPD with a small, stoichiometric flame. Results using the ccFPD, which also exhibits this unusual response, indicate that these high S/N ratios are only partly due to the predictable decrease in flame noise with decreasing flame size. Contrary to expectations, the absolute analyte signal often increases as the flame size decreases to the point of extinction. The signal intensity and the magnitude of the observed changes depend to some degree on the flame composition (H2/O2 ratio).
已开发出一种用于气相色谱的新型分析装置。它基于来自逆流（即反向流动）空气或氧气火焰的光发射，该火焰在氢气和柱流出物的反向流中燃烧。火焰通常“倒置”在面对下部（氢气+流出物）喷嘴的上部（空气）喷嘴上。它也可以位于下部喷嘴上，连接到两个喷嘴，或悬浮在它们之间的间隙中。在这些模式中的任何一种下都可以获得出色的稳定性。总体而言，这种新型“逆流火焰光度检测器”（ccFPD）以传统火焰光度检测器（FPD）的方式对分析物作出响应；然而，它可以在更宽的气体流量范围内运行。例如，相同的物理ccFPD燃烧器很容易支持5至200毫升/分钟的空气流量和相应的5至10,000毫升/分钟的氢气流量的稳定火焰。在存在硫和磷作为测试分析物的情况下对逆流火焰进行目视观察，发现在各种条件下都有强烈、稳定的发光。此外，与商用FPD相比，可以获得质量与传统火焰离子化检测器（FID）产生的信号相似的火焰传导率信号。因此，ccFPD是一种灵活、易于优化的光度检测器。ccFPD的出色流动稳定性被用于探索早期报道的强信噪比（S/N）现象，该现象是从具有小的化学计量火焰的传统FPD中获得的铁族杂元素的现象。使用同样表现出这种异常响应的ccFPD的结果表明，这些高S/N比仅部分归因于随着火焰尺寸减小火焰噪声的可预测降低。与预期相反，绝对分析物信号通常会随着火焰尺寸减小到熄灭点而增加。信号强度和观察到的变化幅度在一定程度上取决于火焰组成（H2/O2比）。
