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Hello I just installed an agilent 6890 in our lab and i am tryign to prove that i have done the modifications and installation correctly. Fortunately the GC doesn't have to be qualified (IQ,OQ,PQ) but i would like to show that it can produce results equivalent to the 6850 we were using before. Anyway to make a long story short i ran 5 replicate Residual Solvent standard injections and got %RSD values ~0.5% and R2 values ~0.9999 and the peak shapes are at least as symetrical as on the 6850 but, the area for all componenets is about 90% the area for the same peaks on the 6850. My question is; is there detector to detector variation or should i expect the results be equivalent. It is possible that i prepared the standards wrong and that is something i have considered but i'd like to get some feedback on this before i'll admit i made a mistake. Thanks Nat

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Nat,

There are a lot of possible reasons for this, most of which are not due to any mistake on your part. Things to consider are:

1. use the same syringe and sample on both instruments.

2. your detector fuel gas flows (assuming it's an FID) may be slighly different

3. are your injector split/splitless conditions exactly the same?

Regards,

Ralph

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Ralph,

Thanks for the suggestions you're correct it is an FID and all of my conditions were the same and i am using static headspace w/ the same headspace autosampler . However, i reprepped the standards i was using and i'll be damned if i didn't make a mistake on the earlier prep. The mean area for all components came out w/in 2-3 % of previously run sets.