As extracts become more dilute their shelf life declines. So when preparing a series of dilutions, it is best to assign shorter dating to the most dilute solutions (>1:1000 v/v) since their potency cannot be guaranteed over time.
When making dilutions, use of the diluentHuman SerumAlbumin (HSA) is recommended since it increases the stability of dilute extracts by preserving the vial’s protein concentration. High protein concentrations are thought to provide potency protection by preventing the allergenic proteins from sticking to the glass, which removes them from solution.