Tocpherol peak shape issue

[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 ?

[ydna1977]

On that note is the ZB-1 column with FT 0.25um suitable and does Squaline as Istd degrade alpha Tocopherol ??

[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.

[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?