The pulse rate is converted to an analog output, which is connected to the data system.īecause it contains only 5 millicuries of Nickel-63, the ECD is covered by a "general license," which requires a periodic wipe test and the filing of a form with your state's Department of Health or Radiation Safety. The detector electronics, which maintain a constant current (about 1 nanoampere) through the electron cloud, are forced to pulse at a faster rate to compensate for the decreased number of free electrons. When electro-negative compounds enter the cell, they immediately combine with some of the electrons, temporarily reducing the number remaining in the electron cloud. This forms a stable cloud of free electrons in the ECD cell. The Nickel-63 emits beta particles (electrons) which collide with the carrier gas molecules, ionizing them in the process. Our ECD consists of a stainless steel cylinder containing radioactive Nickel-63. This chromatogram shows the ECD response to a 200ppb pesticide sample. The ECD offers extreme sensitivity (parts per trillion for SF 6). The ECD detects electronegative compounds, especially chlorinated, fluorinated or brominated molecules such as carbon tetrachloride, bromoform, PCBs and pesticides such as DDT.
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