微小型氢火焰离子化检测器及在色谱中的应用

Development of a Micro-flame Ionization Detector for Portable Gas Chromatography

构建了一种微小型氢火焰离子化检测器(m-FID)。与传统FID不同,助燃空气从收集极上部侧面导入,沿收集极与检测器壳体之间的缝隙向下流动,以环状气流沿壁流入燃烧室,流向反转后从中空的收集极内流出。火焰喷口位于燃烧腔的正中心轴线上,该区域助燃气的流动非常稳定,因此噪音电平非常低。采用更高的极化电压以提高离子化效率。对喷口材料及其内径、收集极长度、收集极至喷口的距离等结构参数进行了优化。在最优条件下,极化电压800 V时,检测器的信噪比比极化电压为150 V时提高一个数量级以上,检出限达1×10-12g/s。相对于常规FID,m-FID的气体消耗降低了70%,仅需要氢气和空气两种气体;具有体积小、重量轻、结构简单、灵敏度高、成本低廉等优点,适合作为便携式微型色谱的通用型检测器。

A micro-flame ionization detector（m-FID） was developed.Differing from the traditional FID,air was introduced from the side of the upper part of the m-FID body,flowing downwards into the burning chamber along a narrow round gap between the collection electrode and the inner wall of the detector body.When the coaxial flow of air reached the bottom of the chamber,it turned 180 and flowed out through the hollow collector.The jet tip was located along the axis of the chamber and the collector,where the air flow was extremely stable,yielding extremely low noise level.A much higher polarization voltage was then applied to enhance ionization efficiency.Several important parameters were optimized,including the material and inner diameter of the jet tip,the length of collector,the distance between jet tip and collector,polarization voltage and gas flow rate.Under the optimized condition,the signal-to-noise ratios improved over one order of magnitude when polarization voltage increased from 150 V to 800 V.The limit of detection of the m-FID was 1×10-12 g/s,with a linear response of five orders of magnitude.Compared with traditional FID,the m-FID only needs two kinds of gases（hydrogen and air） and gas consumption decreases 70%.The detector is small in volume,simple in structure,sensitive and easy to construct,suggesting that it is an excellent detector for portable GC.The m-FID was also applied to analyze five phenolic compounds in real water samples.