Investigation of the interaction of sodium nitrite with hydrogen peroxide in aqueous solutions by the chemiluminescence method

An investigation is made of the chemiluminescence (luminol-dependent and spontaneous) of aqueous solutions of NaNO2 and H2O2 in the pH range of 4.0–9.0. In the presence of luminol at pH>7 the initiator of luminescence is H2O2. At pH<7 the luminescence revealed seems to be initiated by peroxynitric acid (HOONO) produced by the interaction of NaNO2 with H2O2 in weakly acid and acid solutions. Cysteine added to the solution prior to introducing H2O2 completely suppresses luminescence development in the pH range investigated. Moreover, cysteine quenches the luminescence already developed. Mannite and ethanol do not exert a substantial influence on the development of the luminescence. The solution of NaNO2 and H2O2 is also characterized by spontaneous chemiluminescence, the intensity of which is one-two orders of magnitude lower than that of the luminol-dependent chemiluminescence. The intensity of the spontaneous chemiluminescence of the solutions of NaNO2 and H2O attains its maximum in the pH region of 6.5 to 7.0. It is assumed that the revealed spontaneous luminescence of the solutions of NaNO2 and H2O2 is also attributable to formation of peroxynitrit acid in an activated state (HOONO*).