Chromatography Forum

How would the baseline signal for an ECD normally respond if you change the temperature?

I have two ECDs in one instrument. When I turn the detector heaters off, one signal dips a little bit and holds steady (a change from about 30 mV at 350C to about 25mV at room temp).

The signal from the other detector, though, actually increases. At 350C, it was showing 25 mV. At 120C, it was about 180 mV. If I hold the temperature there, the signal holds. If I turn the heater off, the signal gradually rises until it's at about 250 mV at room temperature.

Any thoughts?

How would the baseline signal for an ECD normally respond if you change the temperature?

I have two ECDs in one instrument. When I turn the detector heaters off, one signal dips a little bit and holds steady (a change from about 30 mV at 350C to about 25mV at room temp).

The signal from the other detector, though, actually increases. At 350C, it was showing 25 mV. At 120C, it was about 180 mV. If I hold the temperature there, the signal holds. If I turn the heater off, the signal gradually rises until it's at about 250 mV at room temperature.

Any thoughts?

I could be a leak in the fitting for the detector. I have seen it before that the vespel/graphite ferrules, especially the larger ones that can be on makeup gas adaptor fittings on Agilents, will shrink over time with heating, and when the temperature drops they begin to leak. Usually snugging up the fitting nut solves the problem.

Thanks, that makes sense!

I was curious if Dust-Off would work as a leak detector on an ECD since it has a fluorinated compound, and tried giving the cooled-down detector side a squirt - sure enough, the signal spikes.