Store unopened reagents at 2-8°C. do not use reagents after expiration date, or if turbidity is evident. Before use, bring all reagents to room temperature (18-25°C). Immediately after use, return to proper storage conditions. Lyophilized standards are stable until expiration date. After reconstitution, immediately aliquot standard stock in polypropylene vials at 50 μl per vial anf freeze at -80°C for up to 6 months. If necessary, store at 2-8°C for up to 8 hours prior to aliquotting/freezing. Do not leave reconstituted standard at room temperature.