Improving the Sensitivity of GC/FI Measurements with a New FI Emitter
Introduction
For the field ionization (FI) method, a gas sample is ionized as its electrons move to the emitter (tunneling effect) in a high electric field. This is one of the soft ionization methods in which fragmentation is unlikely to occur. Even if molecular ions cannot be detected from a sample by the electron ionization (EI) method, the FI method can detect molecular ions and obtain molecular mass information, making it an effective ionization method for qualitative analysis. The detection sensitivity of the FI method largely depends on the wire configured in the emitter and the form of the whiskers created on the wire surface. We have developed a new emitter with the wire and conditions for creating whiskers optimized for the FI method in order to improve detection sensitivity. The effectiveness of this emitter is reported below by comparison with conventional emitters.