Lyophilized powder is stable for 12 months after receipt at -20°C. Reconstitute with sterile ddH2O prior to use. To avoid repeated freezing and thawing, aliquot reconstituted stock solution and store at -20°C. Dilute required amount only prior to immediate use. Further dilutions can be made in assay buffer. Note: Sodium azide is a potent inhibitor of peroxidase and should not be added to HRP conjugates. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.