Design of a Combined Photoionization Detector and Photoionization-based Electron-capture Detector

A gas chromatographic detector based on photoionization with characteristics and performance comparable to conventional electron-capture detectors has been constructed. In the electron-capture mode of operation this detector uses a readily photoionizable dopant gas that is ionized by radiation from ultraviolet lamps, and the resulting electrons are collected at the anode under the influence of an applied electrical field. This gives a baseline current that is attenuated by the absorption of electrons by electron-capturing analytes. The detector functions quite satisfactorily, both as a photoionization detector and electron-capture detector. It provides a means of monitoring suitable analytes linearly from picogram to microgram levels. © 1983