Sep 13, 2012 · I even went so far as to do a vial study. I tried four different manufacturers, using both clear and amber vials. For each vial, I did a set of six vials, one injection per vial and checked %RSD. Some vials gave an %RSD as low as under 1%, while the worst offender was over 13%. For any single vial, six injections I got a %RSD under 0.4%.