5 5 dimethyl pyrroline n oxide dmpo

The following trapping reagents were employed to investigate the active species for TC-HCl photodegradation—silver nitrate (AgNO₃), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), 1,4-benzoquinone (BQ), and isopropyl alcohol (IPA)—which act as scavengers for electrons (ē), holes (h⁺), superoxide radicals (•O²⁻) and hydroxyl radicals (•OH). The procedure is the same as the test for photocatalytic activity, except that scavengers are injected before light irradiation. Additionally, the presence of •O²⁻ and •OH radicals was determined via EPR employing the spin-trapping agent 5,5-dimethyl pyrroline-N-oxide (DMPO, Sigma-Aldrich). The DMPO was filtered after being soaked in activated charcoal for 30 min in the dark; its concentration was then measured spectrophotometrically, yielding ε_227nm = 8.0 mM⁻¹ cm⁻¹. The generated spectra were recorded at microwave frequencies of approximately 9.8 GHz, microwave powers of 20 mW, sweep widths of 100 G (centered at 3518 G), and modulation amplitudes of 1 G.

AV-153-Na and AV-154-Na were synthesized in the Laboratory of Membrane Active Compounds at the Latvian Institute of Organic Synthesis. Structures of the AV-153-Na and AV-154-Na are given in Fig. 1; the synthesis of the compounds was performed essentially as described (Dubur & Uldrikis, 1969 ). Tris base, ferrous sulphate, 5,5-dimethylpyrroline-N-oxide (DMPO), Triton-X-100, human serum albumin (HSA), Na₂EDTA, LiCl, NaCl, CaCl₂ and other inorganic salts were purchased from Sigma-Aldrich (Taufkirchen, Germany). Peroxynitrite was synthesized as described by Robinson & Beckman (2005) (link).