Pulsed Discharge Electron Capture Detector Operating in the Constant-Current Mode by Means of Feedback dc Bias Voltage

A feedback dc bias voltage has been utilized to established a constant-current operation mode (cc-mode) for the pulsed discharge electron capture detector (PDECD). The feedback voltage is directly proportional to the concentration of analyte in the detector cell and can function as output. Working in this mode, the PDECD has a linear dynamic range of 1 × 10 5 for CCl 4 and 1 × 10 4 for pesticide almost 1 order of magnitude better than in the previously documented constant-potential mode (cp-mode). The minimum detectable quantity for CCl 4 is 1.5 fg (10 - 15 g) and for lindane, 16 fg. This paper compares the operation of the PDECD in the cc-mode and in the cp-mode. Our findings indicate that a PDECD operating in the cc-mode has relative response, temperature dependence, and dopant gas effects similar to a PDECD in the cp-mode under the same experimental conditions, but has advantages of higher sensitivity, faster response, and simpler operation.