low peak area..

[amithg3]

Hi all,

I am currently trying out a method for alcohol content in an agilent 7800 Gc which was previously run on a varian 3800 GC.

The retention time are exactly the same, but there is a decrease in the peak areas. Using an FID detector.
Will this be a detector or injector problem. The method is same and have been checked. there was no change made to the method. only thing is that its a new GC.

[Steve Reimer]

Why do you think the areas should be the same?

[Peter Apps]

Do the results for alcohol content come out the same on the Agilent as on the Varian ?

Peter

[amithg3]

No, the alcohol content is low with the new GC. Is this related to the applied voltage in the FID?..

[Peter Apps]

Anything that differs between the Agilent and the Varian GCs must affect your samples and your standards almost equally, and consequently the results for alcohol content should come out the same on the two instruments.

Of course I am presuming that you have calibrated the analysis on the Agilent.

So, what has changed besides the instrument ? Have you made up a new batch of standards ?

How much difference is there in peak areas and results between the two instruments ?

Peter

[Consumer Products Guy]

Provide more details.

Are you using internal standard? If so: n-propyl alcohol or ACN?

Are you injecting from aqueous solution? If so, what is the injection volume, the size of the inlet's total volume, split ratio, etc.

Which column type are you using? 624 type, PEG-type?