Chromatography Forum

I have an HP 5890 with dual ECD and I believe that I have leaks at the detectors. What do you think? I replaced the column on the front detector and plugged the rear one. I notced that the reducing nuts that hold the makeup gas adapters were loose so I tightened them a little. When I ran my solvent on the column I had installed I noticed a bumpy base line like I had shot a multiple compound standard or a dirty matrix. I removed the syringe from the ALS and ran with no injection and still noticed the same bumpy baseline. I then noticed that when I change oven temperature the ECD signal goes up and down. Anyone else think that this is a leak at the ECD cells? The signal is still erratic without a column loaded. I'm thinking of cooling down the system and removing the makeup gas adapters and changing the ferrules, but I'm interested in hearing other people's opinions on this problem. What about the makeup gas lines? Should I be checking them for leaks?

Hello!
1-Install properly your column
2-Place a beaker with methylene chloride in our oven...place your oven off...no heat, no fan.
4-Close the door
5-Wait and observe signal of your ECD..if you have a leak, normally, you will have a big signal.

Other test
Disconnect your column from your ECD and cap your detector.
Start oven temp program
Normally, you will have a small signal increase but small....if this signal is high, the problem is your ECD ferrule (make-up), dirty cell or leak cell
for dirty ECD, increase detector temperature .....habitually, HP have 400c max...verify max temp in your manual user.
Thermal cleaning for 4 hours..check if your signal drop

If you have a small increase, column or injector is your problem

Rick

thanks for the tips, I will try some things today.

Signal does increase quite a bit without column installed in the detector and detector plugged. For instance at 50degC signal is 18, at 150degC signal is 30. My guess is a leak at the makeup adapter ferrule so I will try the methylene chloride and check to see if signal increases. thanks

Hi Earl!
Signal increase of 12 is not a high increase.I think that your problem is not your detector.
Try this:
Reconnect your column at your detector and check signal increase from 50 to 150.

Rick,

With column installed the signal increaces then drops and goes back up, leaving a chromatogram that appears to have many peaks. I have been told that the mak-up gas adapter may have a leak. Sound likely?

After reinstalling the column to detector, it is normal that appear some peak (finger print, new column ferrule..ect...)
After 3 ou 4 blank run, normally, you will have no peak.....
Try this and look your signal increase!

Hi Earl!
I'm thinking....I have read again your first message.


You have 2 ECD.....you can connect your column on the other ECD..if you have the same problem, this is your column, if not, this your detector.

It is normal that ferrure loose with temperature,particularly with vespel ferrulle..i use graphite ferrule with my ECD.
If you use Vespel ferrule, it is possible that your ferrule have broken with retight.

Changing the make-up adapter ferrule is more quickly and inexpensive...you will know if it is your problem.....if you have your problem again..try this:
Have you a new column,
Have you change your inlet liner and gold seal plate?
Have you conditionned your column?
Make-up gas is okay?...gas trap, ect...

Good luck!