Always precondition the column before connection to the detector. The pulse interval is usually variable, and in common designs is controlled by the detector electronics in order to maintain constant current in the cell. 100 to 600 Hz is an average frequency range indicating clean operation. Use of a radioactive source is regulated by many governments. Be sure to investigate and observe these regulations.
Performance is equal to or better than detectors with conventional radioactive sources.
In the electron capture mode, the PDD is a selective detector for monitoring high electron affinity compounds such as freons, chlorinated pesticides, and other halogen compounds. For operation in this mode, He and CH4 are introduced just upstream from the column exit. In the helium photoionization mode, the PDD is a universal, non-destructive, high sensitivity detector. The response to both inorganic and organic compounds is linear over a wide range. The PDD in helium photoionization mode is an excellent replacement for flame ionization detectors in petrochemical orrefinery environments, where the flame and use of hydrogen can be problematic.