Chromatography Forum

Hi,
I have a problem with an GC with ECD 2010 from Shimadzu. The baseline is a straight line. It does not fluctuate at all, not even when I change the current or disconnect the ECD from GC. I thought it is dirty, I baked it at high temperature, but no success. I change the column thinking that it may be too dirty also, but again no results. If I shut it down and let it for like 1-2 hours, when I open it will respond on current fluctuation, but when the temperature becomes constant it does not fluctuate, and if I inject a sample no peak can be detected.
Any idea?

Step 1; check that all signal cables are connected and properly plugged in, that the detector is switched on and selected as the active channel on the GC.

Step 2: if your GC has a self-diagnosis proecedure, run it and look up the error codes in the operator's manual

Peter

Thank you for reply Peter.
I checked all the cables but they are okay and it was working fine until Thursday. I run the self-check program and it said that ECD cell frequency is 160 Hz and it should be 40 Hz.

Irina

Hi Irina

What happened between Thursday and when the detector went flatline ? New carrier or make-up gas cylinders ?. Power cuts
?.

Have you checked for leaks ?

Peter

Sounds to me like you have a major contaminate coming in from either your make up gas or your carrier gas. If this is the case it will max out your signal which would cause a straight baseline. I would first check the make up gas.

Hi Irina

What happened between Thursday and when the detector went flatline ? New carrier or make-up gas cylinders ?. Power cuts
?.

Have you checked for leaks ?

Peter

Hi Peter,
I did not change anything and the power wasn't cut. I let it work overnight for a method validation and when I check the batch analysis at every injection had the error " peak integration has not been invoked", but I was setting everything for the method, including retention time. And the detector gave me a flatline. I worked with it in the last four years, but I did not have problems with it. Now I don't know what to do with it and the service can not come until next week.
Irina

Sounds to me like you have a major contaminate coming in from either your make up gas or your carrier gas. If this is the case it will max out your signal which would cause a straight baseline. I would first check the make up gas.

Thank you for the reply.
I would check again all the lines for leaks, but I also have an FID detector on the same GC and it is working fine.

Irina

I found the problem. My ECD is dead. It was oxidized and from time to time it will make contact and gave signal, but at high temperature did not give signal at all. I do not know what was the oxidation cause, because I do only pesticides, pcb’s and trihalomethanes on that detector.
Thank you all for suggestions

Irina

You might consider a swipe survey around your exhaust port at this point. It is possible for the ECD to become coated and not work and it is possible (and very rare) the ECD to vaporize the Ni coating and end up all over the place.

Best regards,

AICMM

You might consider a swipe survey around your exhaust port at this point. It is possible for the ECD to become coated and not work and it is possible (and very rare) the ECD to vaporize the Ni coating and end up all over the place.

Best regards,

AICMM

I will clean around the exhaust port, but regarding the second thing you mentioned I am not sure if I can do something.
My ECD is enclosed in an metallic box and the GC is off. I will not use it until I will change the ECD. When the service guy want to look at the ECD and opened the front part of the box, it is a lead pin that makes the contact with the ECD and when he took that lead pin it came with a part of the ECD (the one that is in contact with the Ni coating). After we found the problem I shut down the instrument and I am waiting for the acquisition of a new ECD. The problem was that because that part was oxidized it will not make contact with the electron meter and I will receive a signal like the one for saturating detector (a false zero).
I hope I made myself understood.

Irina