Normalized Peak Area

Talked about this issue so many time, need to assume that response factor of each component is identical. However, we always negelect that at the assay of total impurities in the samples were performed by normalization method.
So I only recommend to use this method to estimate the relative amounts of small impurities or degradation compounds in a purified component at the specific detector wavelength, that is chromatographic purity.
From my view, the Second maybe ensure a better Repeatability for your results.
or if I were you, I will use manual integrate to get a decent result with batch options.
At the same time, I always double that the column maybe over-load, that mass of analyte per injection is too high, don't you think so?

What is Batch Review in ChemStation?

Huge Time saving with this Batch Review option.
And I also need to learn how to write Excel Macros/Excel VBA, hope john** you could give me some basic knowledge, thanks a lots.

Assay of Vitamin e

H2O + Vitamin D3 (Internal Standards) + Vitamin C Solution (in MeOH) + Sodium Hydroxide. Water bath 30 min, extract with ethyl ester and evaporate to dry, and then dissolve in MeOH. The peak @ rt=2.8 is the problem?(1) Double check the contamination from the needles and HPLC volumetric flash, vials.

(2) If doesn't work, -> what is the concentration of the Sodium Hydroxide? 0.1 N? Do you make sure that the internal standard (Vitamin D3) would not discomposed with the present the anti-oxidant (Vitamin C) during the saponification process?
(3) The final method is that follow the USP method to troubleshooting.