Peroxynitrite (Synonyms: Sodium Peroxynitrite)

Peroxynitrite is formed in vivo by the reaction of NO with superoxide.[1],[2],[3] It is a powerful oxidizing agent that can initiate lipid peroxidation, oxidize sulfhydryls, and nitrate the aromatic residues of proteins.

For long term storage, we suggest that peroxynitrite be stored as supplied at -80°C. It will be stable for at least three months.

Peroxynitrite is supplied as a solution in 0.3 M NaOH. Peroxynitrite is highly unstable and slowly decomposes even at -80°C but not to any significant extent within one month. The half-life of peroxynitrite in alkaline solutions at room temperature is about 5 hours. Peroxynitrite decomposes instantaneously under acidic conditions and the half-life at pH 7.4 is only few seconds ^[3]. Further dilutions of the stock solution can be performed using cold 0.3 M NaOH. We recommend that the actual concentration of peroxynitrite be measured following the procedure given below before using it in any experiments:

Thaw the peroxynitrite solution carefully and keep it on ice. Dilute an aliquot of the stock solution 40-fold with cold 0.3 M NaOH (e.g. add 25 μl of the stock to 975 μl of 0.3 M NaOH) and measure the absorbance at 302 nm with 0.3 M NaOH as blank. Concentration of the stock solution can be calculated using the extinction coefficient for peroxynitrite(1670 M^-1cm^-1).

Reference:
[1]. Pryor, W.A., and Squadrito, G.L. The chemistry of peroxynitrite: A product from the reaction of nitric oxide with superoxide. American Journal of Physiology 268, L699-L722 (1995).
[2]. Beckman, J.S., and Koppenol, W.H. Nitric oxide, superoxide, and peroxynitrite: The good, the bad, and the ugly. Am. J. Physiol. 271(5 Pt 1), C1424-C1437 (1996).
[3]. Koppenol, W.H., Moreno, J.J., Pryor, W.A., et al. Peroxynitrite, a cloaked oxidant formed by nitric oxide and superoxide. Chemical Research in Toxicology 5, 834-842 (1992).