• State Verified Answer
  • Replies 6 replies
  • Subscribers 98 subscribers
  • Views 599 views
  • Users 0 members are here
Related

Agilent Knowledge Portal

Find maintenance, best practice, and troubleshooting articles.

Agilent Knowledge Portal

compounds in end of injection, shifts and making a large diform peak together

carolabo


Hi,

We've been experiencing problems since a little while with our P&T GC/MS for VOC analysis.   We calib with 2 stds, one at conc.2 and the other at conc.20.

The one at conc 20, is as usual.  But the std 2, we lose sensibility for the lasts compounds (1,2,4-trichlorobenzene; naphtalene; 1,2,3-trichlorobenzene).  They are also shifting in retention time and making a large difform peak together in the TIC.

We already done the injector, change the ferrule, cut the column.  Done also the same thing at the interface.  No leaks have been found.

Do someone have ideas to help?

  • 0 in reply to paulsalverda

    Maintenance have been done on the P&T, the buller is cleaned, the trap have been change in august 2016, moisture trap in december 2016.

    The method we're using is the method used here over years...Never had this kind of problem...  The GC column had been change a month ago.  The ion source had been cleaned about 2 months ago.  We tried isolate the P&T a month ago just before changing the column.   The liner we're using is a split straight-throught liner.  We are using  UltiMetal Plus Flexible Metal ferrule .   Our system can also do GC/FID, so we have a switch valv, to switch column and so injectors...  We've also tried isolate the valv with no good results....

  • 0

    Have you done any maintenance on the P&T?  When was the last time the trap was replaced?

    What liner is installed in the GC inlet?  Which inlet, MMI or S/Sl ?   How far up is the column installed into the inlet?

    Are you following all of the recommendations in the Agilent application note for VOC analysis?  Temperatures, times, flows, etc?

    Do you have an injectable liquid standard that you can use to eliminate the P&T?

  • 0 in reply to carolabo

    Do you have an injectable liquid standard that you can use to eliminate the P&T?

     

    What happens if you just install the column from the inlet to the MS?

  • 0

    Make a sample injection into the GC which will bypass the P&T.  If your results are better, you have a P&T water issue.   If the results are the same, you have an inlet issue with the GC.  Do maintenance on the inlet and cheek for leaks.  For water issues, contact your P&T manufacturer. 

  • 0

    I just wanted to follow-up to see if suggestions helped or if there were any other questions. If you were able to resolve this or have any additional information that others may benefit from, please come back to this post to provide an update.

  • 0

    Hello,

    Are you using a water method like 524 or 8260?  I was just wondering because I have similar issues with those compounds at such low concentration for the 8260.  I would recommend adding more points and either going higher unless it is drinking water.  I have to go to 5 ppb to get good results for those on the 8260.  If you need a 2 go to the 524 with 0.5 to 10 ppb.  I have to use at least 5 points.

Was this helpful?
Privacy Statement
Terms of Use
Contact Us
Site Help