Non-radioactive electron capture detector for gas chromatography — A possible replacement for radioactive detectors

Abstract

With detection limits in the low ppbv-range, electron capture detectors (ECD) are the most sensitive GC-detectors available for electron affine compounds, such as pesticides or chlorofluorocarbons. The working principle is based on the generation of free electrons at atmospheric pressure, which are usually emitted from a radioactive Ni-63 source. However, the use of radioactive materials leads to regulatory restrictions regarding purchase, operation and disposal. Recently, we introduced a novel ECD based on a non-radioactive electron source, achieving comparable detection limits, e.g. 1 ppbv (6 ng/l) for 1,1,2-trichloroethane. However, the linear range was still below that of radioactive ECDs. In addition, the detector volume was too large to be used as a GC detector. We now present an improved version of this non-radioactive ECD with significantly increased linear range of 6.5∙103 for 1,1,2-trichloroethane by implementing pulsed operation using a newly developed, autonomous control electronics. In addition, the detector volume is reduced to 100 μl, leading to faster response times, less memory effects and thus less peak broadening. The improved ECD with non-radioactive electron source reaches similar analytical performance compared to commercially available radioactive ECDs and thus can be used as a possible replacement of radioactive ECDs.