Lost Peaks

General discussion of factors that affect chromatographic resolution, peak shape, and noise in the raw data.
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White Queen
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Joined: Tue Dec 08, 2015 9:21 pm

Lost Peaks

Post by White Queen » Tue Dec 08, 2015 9:59 pm

We have seen some problems on our system with losing heavier targets when we run our PAMS retention time standard. It seems that m&p xylene, propylbenzene, and the tri-methylbenzenes are gone. At first we just figured it was the canister that had gone bad but when we replaced it we still had problems. I am concerned that there is something wrong with the trap or the column.

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Red Queen
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Joined: Tue Dec 08, 2015 11:31 am

Re: Lost Peaks

Post by Red Queen » Tue Dec 08, 2015 10:04 pm

More royalty, nice!
Like you, I would suspect the can first but if that has been ruled out then I would consider the trap before the column. I don't think I have ever seen a BP column fail to clear these peaks unless trap material or ferrule material got into the column and partially plugged it. If you haven't changed the column or restrictor I would look at the trap. If trap material gets out of the trap into an unheated area it can cause all kinds of grief.
Off with their heads! _________________________________________________________________

In God we trust, all others must bring data.
W. Edwards Demming

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Mad Hatter
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Joined: Tue Dec 08, 2015 9:07 pm

Re: Lost Peaks

Post by Mad Hatter » Tue Dec 08, 2015 10:07 pm

I agree with Red. Do you run blanks after your PAMS sample? Sometimes this can give more information. We have seen the heavies disappear in the QC sample and show up in the blank after it. This has been a problem with steel sample lines or sometimes if graphite ferrules come apart.

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