P8.8 - Electron Capture Detector Based on X-rays
- 15. Dresdner Sensor-Symposium 2021
2021-12-06 - 2021-12-08
- P8. Neuartige Sensormaterialien und -technologien
- N. Solle, E. Bunert, S. Zimmermann - Leibniz University Hannover/D
- 281 - 284
Electron capture detectors (ECDs), first introduced by J.E. Lovelock in 1958 , are characterized by their simple design and low limits of detection in the pptv range for substances with high electron affinity such as pesticides or halogenated compounds [1,2]. Thus, ECDs are often used in environmental analytics . In classical ECDs a radioactive 63Ni foil is used to ionize a carrier gas, e.g. nitrogen, generating thermalized electrons. These electrons drift towards a detector in an electric field resulting in a constant electron detector current. Analytes with sufficient electron affinity capture the thermalized electrons and are flushed out of the ECD with the carrier gas flow. Thus, the electron current reaching the detector is decreased and a measure for the analyte concentration. Pulsed operation was later introduced by R.J. Maggs et al. which increased the linear dynamic range to 104 . Usually, radioactive ionization sources are used in ECDs because they require no maintenance and no additional power supply. However, radioactive materials are subject to regulations and costs for disposal. Therefore, despite the excellent detection limits for substances with high electron affinities, today, radioactive ECDs can be rarely found as detectors, e.g. in gas chromatography (GC).