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Detector ECD |
Atenção:
Este detector requer licença do CNEN
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Detector de Captura de Elétrons instalado em modulo
SRI-110
ECD - Electron Capture Detector
Model 110 Stand-alone
GC Detector Chassis |
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Thermostatted from Ambient to 375oC
- Offers
Extreme Sensitivity—down to 10ppt
- Detects
Electronegative Compounds
- Mandated
for Pesticides and PCBs
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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). The ECD may be
thermostatted from ambient to 375oC. |
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The ECD detects
electronegative compounds, especially chlorinated, fluorinated or
brominated molecules such as carbon tetrachloride, bromoform, PCBs and
pesticides such as DDT. The ECD offers extreme sensitivity (parts per
trillion for SF6). |
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This chromatogram shows the ECD response to a 200ppb pesticide sample. |
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Our ECD consists
of a stainless steel cylinder containing radioactive Nickel-63. The
Nickel-63 emits beta particles (electrons) which collide with the
carrier gas molecules, ionizing them in the process. This forms a stable
cloud of free electrons in the ECD cell. When electro-negative compounds
enter the cell, they immediately combine with some of the electrons,
temporarily reducing the number remaining in the electron cloud. 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. The pulse
rate is converted to an analog output, which is connected to the data
system.
Because 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. In most states,
no annual fee is required.
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