Trouble with Acetic Acid analysis by GC

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Ljh133
Ljh133's picture
Trouble with Acetic Acid analysis by GC

Hi,  I am working on an application right now trying to analyse acetic acid in small quantities in an aqueous medium.  I am using a Perkin Elmer GC with a FFAP column and FID.  When injecting my standard (made up in water from Sigma) there is a broad split peak where the acetic acid is supposed to be.  I injected neat glacial acetic acid and there was a nice peak, no broadening or splitting.  Then I injected water (no response as you would expect with FID).  Is is possible that the water is changing the peak shape of the acetic acid and interferring? The inlet is at 200, oven at 180 and detector at 220.  Also I the linear is loosely packed with quartz glass.  Any comments?

Dr. Analytical
Dr. Analytical's picture
Is this a split or splitless

Is this a split or splitless injection?  Please give us some more details.

It is possible for the solvent to cause peak shape problems, but you should check some other issues first.  Splitting and broadening can come from either an overloaded system or a number of injection problems, or maybe even a bad stationary phase.

Have you tried changing the concentration of acetic acid?  Is there any difference in the splitting?
What are your column dimensions and injection volume?  Have you tried different volumes?

Try varying some of these parameters to see if any make a difference, and then report back here.

Thanks for posting on scientistsolutions.com.  Come back often.

wildroseGC
wildroseGC's picture
you use FID, and you inject

you use FID, and you inject water, water is very polar, that will cause flame out. why did you inject water?
  thank you

viswaraja
viswaraja's picture
I had faced a similar problem

I had faced a similar problem when using GC-FID with headspace whilst trying to quantitate acetic acid acid content at trace levels.

Acetic acid in the presence of water starts dissociating into acetate ions. If it dissociates fully then you don't get a peak at all. If u inject neat glacial acetic acid the peak should be fantastic with grt symmetry and resolution. If it is partially dissociated you get split responses. In the last case there might be issues with mean RSD for replicate injections.

I had used a DB-624 column as the experiment was for residual solvents in pharmacutical API matrix

The moral of the story is that try changing the medium. If u inject acetic acid in DMSO or DMF solvents in lieu for H20 that solves the issue completely and the quantification becomes perfect.

If you have any more queries please add supplementary queries.

vinod bhadane
vinod bhadane's picture
I Already have method for

I Already have method for material which dissolve in N N Dimethylformamide , But the material which insoluble in same criteria then ! So Please Suggest solution

viswaraja
viswaraja's picture
One can use any high boiler

One can use any high boiler solvents........