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Tocpherol peak shape issue
Posted: Thu Oct 24, 2019 11:56 am
by ydna1977
Hi
Following Ep monograph assay and RS 07/2011:0692 for alpha tocopherol peak fronting badly for Internal std and Vit peak
this normal or exceeding column capacity for Ref A although criteria states min 0.6 symmetry factor ?
Re: Tocpherol peak shape issue
Posted: Fri Oct 25, 2019 12:51 pm
by ydna1977
On that note is the ZB-1 column with FT 0.25um suitable and does Squaline as Istd degrade alpha Tocopherol ??
Re: Tocpherol peak shape issue
Posted: Fri Nov 01, 2019 11:46 am
by RiainG
I am currently running the same method and i'm having no issues with peak shape. Symmetry factor of 0.9.
My conditions for your reference;
GC 6890
DB-1, 30m x 0.25 x 0.25
Oven - 280oC
Inlet - 290oC
Detector - 290oC
Helium - 1ml/min
Split ratio: 1:100 (rel subs)
1:350 (assay)
Injection vol: 1ul (rel subs)
0.5ul (assay)
The change in split/injection volume between rel subs and assay was a recommendation from our validation of the method.
Re: Tocpherol peak shape issue
Posted: Mon Nov 04, 2019 11:37 am
by ydna1977
if the injection volumes and split ratio altered was this justified by USP <621> tolerances or revalidation required ? ie
Injection Volume (GC, HPLC): can be reduced as far as is consistent with accepted precision and detection limits.
Then compare results and justify reducing inj vol?