Li Jian Jun, Thurbide Kevin B
Department of Chemistry, University of Calgary, University Drive, NW, Calgary, Alberta, Canada.
J Sep Sci. 2009 Jul;32(14):2469-75. doi: 10.1002/jssc.200900177.
Remote control of the vent/detector split flow ratio in packed column supercritical fluid chromatography (pSFC) with flame ionization detector (FID) is demonstrated using a dual heated restrictor method. Restrictors stemming from a Tee at the separation column outlet were, respectively, fixed into an FID and a vent port, and their individual temperatures were controlled using resistively heated wires. Subsequently, both system pressure and split flow could be manipulated. For example, for applied restrictor temperatures examined up to 600 degrees C, corresponding vent/FID split flow ratios between 2 and 7 were observed depending on the port heated. As well, column pressures around 16-23 MPa were also achievable over the same range. Conversely, isobaric altering of the split flow ratio was possible when opposing positive and negative temperature gradients were applied at the two restrictors. Under these conditions, the system pressure varied less than 1% RSD over a 10 min period. As an application, the method was used to establish stable detector operation in the analysis of n-alkanes under pSFC-FID conditions that initiated flame instability. Results indicate that this technique could be a relatively simple and inexpensive means of controlling system pressure and detector split flow ratios in pSFC-FID.
采用双加热限流器方法，展示了在配备火焰离子化检测器（FID）的填充柱超临界流体色谱（pSFC）中对分流/检测器分流比的远程控制。源自分离柱出口三通的限流器分别固定在FID和排气口上，并使用电阻加热丝控制其各自的温度。随后，可以操纵系统压力和分流。例如，对于高达600℃的应用限流器温度，根据加热的端口不同，观察到相应的排气口/FID分流比在2至7之间。同样，在相同范围内也可实现约16 - 23MPa的柱压。相反，当在两个限流器上施加相反的正负温度梯度时，分流比的等压改变是可能的。在这些条件下，系统压力在10分钟内的变化小于1%RSD。作为一种应用，该方法用于在pSFC - FID条件下分析正构烷烃时建立稳定的检测器操作，这种条件会引发火焰不稳定。结果表明，该技术可能是一种在pSFC - FID中控制体系压力和检测器分流比的相对简单且廉价的方法。
