I have two Agilent Technologies 6890 GC's in my lab. The first one is 3 years old, the other one came a week ago. ECD signal on the older one is 45 (oven temperature 100 oC, column instaled)whereas the signal on the newer one is 150 (detector capped, no column instaled). The engineer told me that signal is still OK. But, both detectors are G2397A micro ECDs and both use the same nitrogen make up gas, so why the signals are so diffrent? What is the operating signal range of Agilent micro ECD?