title: A practical method for preparing peroxynitrite solutions of low ionic strength and free of hydrogen peroxide.
abstract: The reaction of ozone (approximately 5% in oxygen) with sodium azide (0.02-0.2 M in water) at pH 12 and 0-4 degrees C is shown to yield concentrated, stable peroxynitrite solutions of up to 80 mM. The product of this reaction is identified based on a broad absorption spectrum with a maximum around 302 nm and by its first-order rate of decomposition (k = 0.40 +/- 0.01 s-1 at pH 7.05 and 25 degrees C). These peroxynitrite solutions can be obtained essentially free of hydrogen peroxide (detection limit 1 microM) and only traces of azide (detection limit 0.1 mM). They are low in ionic strength and have a pH of about 12 but without buffering capacity; therefore, they can be adjusted to any pH by addition of buffer. These preparations of peroxynitrite frozen at -20 degrees C show negligible decomposition for about 3 weeks of storage and follow a first-order decomposition with a halflife of about 7 days at refrigerator temperatures (approximately 5 degrees C). These preparations give reactions that are characteristic of peroxynitrite. For example, at pH 7.0, they react with L-tyrosine to give a 7.3 mol % yield of nitrotyrosine(s), and with dimethyl sulfoxide to give a 8.2 mol % yield of formaldehyde, based on starting peroxynitrite concentration.
authors.affiliation: Biodynamics Institute, Louisiana State University, Baton Rouge 70803-1800.
authors.forename: W A
authors.initials: WA
authors.lastname: Pryor
authors.forename: R
authors.initials: R
authors.lastname: Cueto
authors.forename: X
authors.initials: X
authors.lastname: Jin
authors.forename: W H
authors.initials: WH
authors.lastname: Koppenol
authors.forename: M
authors.initials: M
authors.lastname: Ngu-Schwemlein
authors.forename: G L
authors.initials: GL
authors.lastname: Squadrito
authors.forename: P L
authors.initials: PL
authors.lastname: Uppu
authors.forename: R M
authors.initials: RM
authors.lastname: Uppu
mesh_terms: D001386:Azides / Q000737:chemistry; D002021:Buffers; D004340:Drug Contamination / Q000517:prevention & control; D004355:Drug Stability; D005609:Free Radicals; D005615:Freezing; D006861:Hydrogen Peroxide; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000737:chemistry*; D009994:Osmolar Concentration; D010126:Ozone / Q000737:chemistry; D019810:Sodium Azide; D012996:Solutions; D013053:Spectrophotometry; D014443:Tyrosine / Q000737:chemistry
chemical_list: D001386:Azides; D002021:Buffers; D005609:Free Radicals; D009566:Nitrates; D012996:Solutions; C039642:peroxynitric acid; D014443:Tyrosine; D010126:Ozone; D019810:Sodium Azide; D006861:Hydrogen Peroxide