I do calibration curves both ways, but I have no idea whether I'm acceptable...

My feeling is that making different volume injections from one vial shouldn't be a problem provided the injection solvent is weak. In fact this is something I do get upset about, and I very, very rarely inject samples in a solvent stronger than the start of the gradient. Also I don't tend to push limits on high-volume injections; I can't remember the last time I injected more than 20uL on a 2mm column.

The usual advantage people cite for making multiple standards at different concentrations and injecting the same volume of each, is that the calibration points are somehow more independant. I sort-of feel this is a bit of a spurious argument because they've usually been derived from a single stock by some manual dilution process. And yes, the autosamplers in my lab are definitely better than me at pipetting.

On the other hand, when using the Surveyor system in our lab, I always use multiple vials, because for various reasons I don't entirely trust its injection volumes to be accurate (although I do trust them to be repeatable).

Of course, the trouble with multiple vials is that they're more expensive on consumables!
Hello Tom !
This is guideline document, project of guideline, scientific paper, or frendly recomendation (board)?
To know what is being prepared for testing by WHO...
To Gclc
http://www.edqm.eu/medias/fichiers/Anne ... ipment.pdf