Chlorinated phenols affect GC column?

Discussions about GC and other "gas phase" separation techniques.

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I am running chlorinated phenols using DB1701 column with MSD. After tens of injection, I noticed the signal intensities became lower and finally one of them cannot be seen. It could be related to the column degradation or contamination of the mass spectrometer. Anyone has any suggestions?
What is the matrix?
Is this something like method 8270?
Doe you see all analytes decrease? Have you tried something else?
I am doing a solvent calibation - chlorinated phenols (CPs) in acetonitrile were derivatized with BSTFA and analyzed with a GC-MS (DB1701 column).

It was working alright before, but after the instrument ran a few dirty samples (beef liver as matrix), the sensitivities for most of the CPs dropped with the one of the CPs cannot be detected. I cleaned the ion source (EI), replaced the liner, septum, gold seal, and guard column, but it did not resolve the problem, i.e. I could detect most of the CPs, with one being still missing.

Today, I ran the samples using another GC-MS (the same type of instrument), I could see all of the CPs again, indicating that somewhere of the original GC-MS giving the trouble, but no idea where. I am going to replace the analytical column tomorrow to see if this can get the problem resolved. I have never worked with multi-halogenated organics using the GC before, therefore, have no idea if this type of organics degerade the column or mass spectrometer.

Any suggestions? Many thanks.
Simon001 wrote:
I am going to replace the analytical column tomorrow to see if this can get the problem resolved.


We felt that it was always a good practice to have a new spare analytical column in the drawer, for potential troubleshooting.

In your case, I'd also do inlet cleaning/maintenance.

Sounds to me like more of a GC issue than a detector issue.
I have just replaced the analytical column and hope it can resolve the issue.

One suggestion from the forum says a possible contamination might be from the BSTFA, the derivatization reagent I am using in my analysis. But I do not have specific idea about such a possible contamination source.
When we did fish tissue for chlorophenols any fats accumulating on the column or in the system would cause their peak widths to become so wide that they were undetectable.
It made it worthwhile to come up with a better cleanup technique. As a side benefit the source didn't smell like fish oil.
@Steve Reimer: thanks for the sharing. I am working with the solvent calibrations. But a possible contamination could be from dirty samples (beef samples) injected into the GC-MS before I start this chlorophenol project.
@Steve Reimer: I just wonder what clean-up technique you used for the fish sample when you analyzed chlorophenols. Is there any paper that I can reference to?
Thanks a lot!
Simon001 wrote:
@Steve Reimer: I just wonder what clean-up technique you used for the fish sample when you analyzed chlorophenols. Is there any paper that I can reference to?
Thanks a lot!


Restek makes a solid phase extraction cartridge with Graphitized Carbon Black and Primary Secondary Amine (GCB/PSA) that we are experimenting with to clean up Hemp extracts for pesticide work. The analytes are similar to chlorinated phenols and the cleanup removes lipids and chlorophyll so it might help to clean up the liver samples. You would just have to try it and see if you get acceptable recovery of the analytes of interest.
The past is there to guide us into the future, not to dwell in.
@James_Ball: thanks a lot for your response. Has your work got published? I just want to learn a detailed procedure for the fish sample clean-up.
Simon001 wrote:
@James_Ball: thanks a lot for your response. Has your work got published? I just want to learn a detailed procedure for the fish sample clean-up.


My work doesn't get published unfortunately, but the Restek website has several application notes and blog posts concerning such techniques. You can also email them with your testing parameters and they can recommend a process to try. Likewise UCT(united chemtech) and Phenomenex also have good support services who can help with applications of sample cleanup. They are all glad to help, because if you are published and make note of the product you used, it is free promotion for them :)
The past is there to guide us into the future, not to dwell in.
@James_Ball: I will contact them. Many thanks to your response!!
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