Freeze-Dried positive control for Penicillin G has a final concentration of 5 ug/L after dissolution and can be used with cow milk or milk from other species. Make sure that milk used to dissolve this control is free of inhibitors.
This reagent should be stored under refrigeration until use. Once the powder has been dissolved can be kept frozen for several days, but never under refrigeration.
Add 5 ml of milk (negative control) to the vial and stir gently. Leave the solution for 15 min at room temperature and stir the vial few times during that time for full dissolution.