title: Non-Thermal Plasma in Contact with Water: The Origin of Species.
abstract: Non-thermal atmospheric pressure plasma has attracted considerable attention in recent years due to its potential for biomedical applications. Determining the mechanism of the formation of reactive species in liquid treated with plasma is thus of paramount importance for both fundamental and applied research. In this work, the origin of reactive species in plasma-treated aqueous solutions was investigated by using spin-trapping, hydrogen and oxygen isotopic labelling and electron paramagnetic resonance (EPR) spectroscopy. The species originating from molecules in the liquid phase and those introduced with the feed gas were differentiated by EPR and1H NMR analysis of liquid samples. The effects of water vapour and oxygen admixtures in the feed gas were investigated. All the reactive species detected in the liquid samples were shown to be formed largely in the plasma gas phase. It is suggested that hydrogen peroxide (determined by UV/Vis analysis) is formed primarily in the plasma tube, whereas the radical species ⋅OOH, ⋅OH and ⋅H are proposed to originate from the region between the plasma nozzle and the liquid sample.
authors.affiliation: Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.|York Plasma Institute, Department of Physics, University of York, Heslington, York, YO10 5DQ, UK.
authors.forename: Yury
authors.initials: Y
authors.lastname: Gorbanev
authors.affiliation: York Plasma Institute, Department of Physics, University of York, Heslington, York, YO10 5DQ, UK. deborah.oconnell@york.ac.uk.
authors.forename: Deborah
authors.initials: D
authors.lastname: O'Connell
authors.affiliation: Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK. victor.chechik@york.ac.uk.
authors.forename: Victor
authors.initials: V
authors.lastname: Chechik
keywords: EPR spectroscopy; isotopic labelling; plasma chemistry; radicals; reactive oxygen species
references.citation: J R Soc Interface. 2013 Sep 25;10(89):20130591
references.pmid: 24068175
references.citation: J Clin Biochem Nutr. 2010 Jul;47(1):1-11
references.pmid: 20664724
references.citation: Environ Sci Technol. 2010 May 1;44(9):3505-7
references.pmid: 20392084
references.citation: Biomol Ther (Seoul). 2014 Nov;22(6):477-90
references.pmid: 25489414
references.citation: PLoS One. 2015 Aug 28;10(8):e0136956
references.pmid: 26318000
references.citation: PLoS One. 2015 Jun 05;10(6):e0128205
references.pmid: 26046915
references.citation: Chemistry. 2016 Mar 1;22(10):3496-3505
references.pmid: 26833560
references.citation: Biointerphases. 2015 Jun 06;10(2):029518
references.pmid: 25947392
references.citation: Biointerphases. 2015 Jun 01;10(2):029506
references.pmid: 25832438
references.citation: Free Radic Biol Med. 1987;3(4):259-303
references.pmid: 2826304
references.citation: Nature. 1976 Sep 30;263(5576):442-3
references.pmid: 972689
references.citation: Br J Cancer. 2015 Apr 28;112(9):1536-45
references.pmid: 25839988