Detection of methyl, hydroxymethyl and hydroxyethyl hydroperoxides in air and precipitation.

It is well established that organic peroxides are formed by OH-radical-induced oxidation of hydrocarbons under atmospheric conditions1. Peroxyacyl nitrates have been known to be constituents of polluted air since the 1950s2,3. In a recent study we have shown that the gas-phase reaction of ozone with a variety of natural and anthropogenic alkenes can contribute to the formation of hydro-philic organic peroxides4. Indications that such peroxides are actually present in the environment have been obtained previously by measurements of the peroxide content of cloudwater and rain. In the absence of a specific analytical method the peroxide content after selective enzymatic destruction of the hydrogen peroxide was taken to be the organic peroxide fraction5-7. In this letter we report the determination by high-performance liquid chroma-tography of methyl (MHP; CH3OOH), hydroxymethyl (HMP; HOCH2OOH) and 1-hydroxyethyl (HEP; CH3CH(OH)OOH) hydroperoxides, in addition to H2O2, and present some preliminary concentration ranges in air and precipitation. The existence of this class of atmospheric trace constituents raises questions about possible adverse biological effects

Hydroxymethyl hydroperoxide and bis(hydroxymethyl) peroxide fom gas-phase ozonolysis of naturally occurring alkenes.

Ozonolysis is one of the main pathways for degradation of alkenes in the atmosphere, where the reaction is associated with smog formation1 and the haze that often occurs over forests2,3. In recent decades, ground-level ozone concentrations have greatly increased4,5. The possibility of significant damage to plants by ozone and its products has consequently been raised in discussions of ‘waldsterben’, the large-scale dying of trees in northern Europe and North America6–9. With particular regard to the formation of peroxides, we have used 13C- nuclear magnetic resonance (NMR) to investigate the water-soluble products of the gas-phase ozonolysis of isoprene and several terpenes, which are emitted into the atmosphere in large quantities (108–109 tonnes yr−1 globally) by trees3,10,11. All these alkenes yield bis(hydroxymethyl)peroxide (BHMP; HOCH2OOCH2OH). The apparent precursor of BHMP is hydroxymethyl hydroperoxide (HMP; HOCH2OOH), which results from addition of water to the ozonolysis intermediate. As both HMP and BHMP have various toxic effects on plant cells and enzymes12–14, we point out here an indirect way by which ozone may adversely affect forests