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. The ECD offers extreme sensitivity (parts per trillion for SF6). The ECD detects electronegative compounds, especially chlorinated, fluorinated or brominated molecules such as carbon tetrachloride, bromoform, PCBs and pesticides such as DDT. The ECD may be thermostatted from ambient to 375☌. The SRI Electron Capture Detector can be operated with either nitrogen or argon-5% methane (P5) makeup gas, and nitrogen, P5, or helium carrier (as long as the helium flow is less than 10 milliliters per minute). Offers extreme sensitivity-down to 10 ppt.
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