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. 2016 Jun 20;11(6):e0157922. doi: 10.1371/journal.pone.0157922

Fig 8. Reactive chemical species are generated during operation of the nitrogen gas plasma instrument.

Fig 8

Chemical indicator strips were used to detect the generation of reactive chemical species during operation of the nitrogen gas plasma device. Specifically, we tested for hydrogen peroxide [Merckoquant® Peroxide Test 0.5–25 mg/l H2O2, Merck KGaA, Darmstadt, Germany] (A), nitrate (NO3-) [Merckoquant® Nitrate Test 10–500 mg/l NO3-, Merck KGaA] (B), and nitrite (NO2-) [Merckoquant® Nitrite Test 2–80 mg/l NO2-, Merck KGaA] (C). In each case, the strip was placed on the earth electrode of the BLP-TES instrument. Nitrogen gas plasma treatment was then performed at 1.5 kpps for 0, 5, or 15 min (N = 3). After treatment, the strips were immediately dipped into pure water (Otsuka distilled water; Otsuka Pharmaceutical Co. Ltd., Tokyo, Japan). The concentration of hydrogen peroxide, nitrate, and nitrite was estimated from the change in colour of the corresponding chemical indicator strip, which was scanned and compared with a calibration curve of references. Differences where p<0.05(*) and p<0.01(**) versus control (0 min) were considered significant or not significant (NS).