Reproducibility Issues after system maintenance

Please read up on split and splitless along with inlet maintenance in the GC manuals. 

There are many resources on Agilent.com and here on the Agilent Customer Community.

Maintaining Your Agilent Split/Splitless GC Inlet

Maintaining Your Agilent Split/Splitless GC Inlet - same title, different presentation!

Understanding the GC Inlet. Which one is more appropriate for your method? (agilent.com)

(+) Column Installation - Split/Splitless and Multimode inlets =and= SQ and TQ MS transferlines - Files - GC/MS - Agilent Community

There are some easy questions to start with.  What is your column configuration?  Is it set properly in the software?  You have a guard column, then two columns with a PUU and going to vaccum in the Mass Spec, is the software and method configured properly?  Does column 2 have about 0.1 to 0.2 ml/min MORE than column 1?  This is necessary so that there is always positive flow from the PUU supply so that sample can't go up the PUU gas supply line.    What is your splitless  Purge ON time? What is your inlet temperature and initial oven temperature and initial oven hold time?

The cross gold seal is not necessary.  The cross seal is only required if you are running in modes with very high inlet flows, like split over some few hundred ml/min, or have samples with so much residue that collects on the gold seal that it can become clogged  (this would mean that you should do dramatically more inlet maintenance). 

Thank you very much. Will work through this. I am not totally sure about the column installation. Our system is set up in a way that the flow that goes though the sequence of guard column-PUU-analytical column-PUU-MS Transfer Lines is viewed as one column as far as I understand, so there is only one column and I cannot set the gas flow differently for the different parts of it as it goes from the inlet into the guard column which is connected to analytical column (through 1st PUU), which is then connected to the MS transfer line (through 2nd PUU) and then to the MS. All 3 columns have the same dmensions. Guard column and MS transfer line ar deactivated fused silica. Maybe I need to reconfigure that. I'll look into that using the resources you shared.

And yes, we are injecting a polymer that is non volatile and gets stuck on the liner. It is possible that some of that is collecting in the liner as even burn-outs of inlet and column do not fully get rid of residual peaks.

The column has been used for a loooong time and this material has been injected many times over these past few years. We had a PM done by Agilent last year and I'm pretty sure they cleaned the inlet, but since then we did lots of development work which involved the injection of non-volatiles and compounds with very high boiling points of which I also see impurities in the blanks.

I may have more questions once I went through all the material you shared

I've been working on these a very long time. You'll get it!  Let me know what you think about the source cleaning videos.

The tune looks good except for the air leak. 

Hi Paul,

Please make video of replacement of different different boards of 5977 or 5975.

It will be really helpful to agilent community..

Replacing boards is not something I would recommend to anyone who has not attended service training inside Agilent.  There is too much chance of causing more problems or getting hurt.   There are documented procedures in the publicly available manuals.  

5977B Series MSD Troubleshooting and Maintenance Manual (PDF)

 https://www.agilent.com/cs/library/usermanuals/public/user-manual-gc-msd-system-5977B-series-G7077-90035-en-agilent.pdf

Are you suggesting that I should  clean the source? I think I will need to order some tools and I think aluminum oxide powder. I remember some of it when Sarah did this in the beginning of the year

I watched the first 35 minutes of the source cleaning video. It is really thorough and makes me feel that I can do it. Knowing what all these parts do and what's happening inside the MS is really useful and helps to understand why regular maintenance of the source is important. Could you tell me which values to monitor for the tunes? You mentioned lens voltage. Is there anything else?

I watched the first 35 minutes of the source cleaning video. It is really thorough and makes me feel that I can do it. Knowing what all these parts do and what's happening inside the MS is really useful and helps to understand why regular maintenance of the source is important. Could you tell me which values to monitor for the tunes? You mentioned lens voltage. Is there anything else?