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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?

Parents
  • 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?

Reply
  • 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?

Children
  • 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 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?

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