Pulsed-Discharge Electron-Capture Detector: Kinetic Model, Response Factors, and Temperature Dependence

The absolute electron capture coefficient, KEC, for a variety of compounds that undergo different electron capture mechanisms is determined by using a pulsed-discharge electron capture detector (PDECD). The temperature dependence of the representative compounds is measured. Two different dopant gases, hydrogen and methane, are used. The relative responses cover 5–6 orders of magnitude, just as in the radioactive ECD. The exceptions are discussed. The absolute response factors of the PDECD are greater than for the radioactive ECD for most compounds and are much greater for the alkyl iodides. The general temperature dependence is similar to that in the radioactive ECD. The results are discussed in terms of the kinetic model for ECDs. These results have been used to develop a commercial, nonradioactive ECD that is now being field-tested.