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- Posts: 4
- Joined: Sat Jul 18, 2015 1:32 am
A colleague of mine is having reproducibility issues and is convinced that his analytes are either selectively evaporating from sealed HPLC vials, or are reacting with the vials themselves. The first theory seems suspect to me given the vapor pressures of the analytes. Only vinyl acetate could show this behavior, but it is dissolved in diluent (water/ACN I believe), and the vials are kept in a sample chiller at 4 C.
So far, his solution to this problem is to vial the standard prior to each injection. This makes absolutely no sense to me, he takes his standard flask out of a fridge at 4C, vials it, and then places it in a sample chiller which is also at 4 C.
If anyone worked with these analytes or this specific method, please enlighten me. Is there an inherent problem with the USP Copovidone method or is this a case of operator error?