Stock solutions can be sterilized by 0.2 um filtration, we recommend using Mini Syringe Filters for filtration of small volumes (see related products). Solutions are stable for up to a week when stored at 4°C, protected from light. For longer term storage, single-use aliquots of the 50 ug/mL stock can be stored at -20°C, although freezing can result in lower fluorescence. BSA can be added at 1 mg/mL final concentration to stabilize stock solutions during freezing. Aliquots should not be refrozen after thawing. Do not store dilute solutions of Annexin V in PBS