Sonolysis of concentrated aqueous solutions of nonvolatile solutes: spin-trapping evidence for free radicals formed by pyrolysis.
The sonolysis of argon-saturated aqueous solutions of sodium acetate, sodium propionate, amino acids, and sugars was investigated by ESR and spin trapping over a large range of concentrations. The spin trap 3,5-dibromo-2,6-dideutero-4-nitrosobenzene sulfonate was used to examine the possibility of detecting new radicals specifically generated in the high temperature zones surrounding the collapsing cavitation bubbles. At lower concentrations of these solutes, no evidence for specific new radicals formed in the high temperature regions induced by cavitation could be found, and only radicals formed by hydroxyl radical and hydrogen atom abstraction reactions could be detected. These were identified by comparison with the radicals produced by uv photolysis in the presence of hydrogen peroxide. However, at higher concentrations, new radicals (typically methyl radicals) formed in the high temperature interfacial regions induced by cavitation were found for sodium acetate, sodium propionate, amino acids, and sugars (D-mannose, D-glucose, 2-deoxy-D-ribose). These results indicate that pyrolysis radicals can be detected when the nonvolatile solutes are present at high concentrations in the interfacial regions of the cavitation bubbles.
Kondo
T
T
Division of Cancer Treatment, National Cancer Institute, Bethesda, Maryland 20892.
Murali Krishna
C
C
Riesz
P
P
D000085:Acetates; D019342:Acetic Acid; D000596:Amino Acids; D001557:Benzenesulfonates; D002241:Carbohydrates; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D009603:Nitroso Compounds; D011422:Propionates; D012996:Solutions; D013113:Spin Labels; D014465:Ultrasonics; D014867:Water
D000085:Acetates; D000596:Amino Acids; D001557:Benzenesulfonates; D002241:Carbohydrates; D005609:Free Radicals; D009603:Nitroso Compounds; D011422:Propionates; D012996:Solutions; D013113:Spin Labels; D014867:Water; C048757:3,5-dibromo-4-nitrosobenzenesulfonate; C514135:sodium propionate; C029658:propionic acid; D019342:Acetic Acid