Specificity of detection methods of nitrites and ozone in aqueous solutions activated by air plasma

Air transient spark (TS) discharge generates cold plasma, which is a rich source of reactive oxygen and nitrogen species (RONS). The gaseous products both in ambient air and air humidified by water electrospray (ES) are nitrogen oxides (NO and NO2). The rotational and vibrational temperatures determined by optical emission spectroscopy (OES) are lower with water ES through the discharge than in ambient air, which reduces the formation of NOx. The investigation of the specificity of Griess colorimetric assay for the detection of long‐lived nitrites in plasma activated solutions confirms its accuracy by comparison with ion chromatography (IC) and excludes possible interferences with hydrogen peroxide by using the enzyme catalase. Examination of the specificity of the Indigo blue assay for ozone detection shows strong interferences with the peroxynitrite chemistry. Phenol as the chemical probe confirms that the TS air discharge produces no aqueous ozone. Cold air plasma of transient spark discharge with water electrospray promotes the transfer of gaseous reactive species, mainly NOx, into the plasma activated water solutions resulting in aqueous H2O2, nitrites, and nitrates. Methods for the detection of the long‐lived aqueous RONS: Griess assay (nitrites) and Indigo blue method (ozone) are examined for their specificity and possible interferences.