HENRYS LAW CONSTANT DETERMINATIONS FOR HYDROGEN-PEROXIDE, METHYL HYDROPEROXIDE, HYDROXYMETHYL HYDROPEROXIDE, ETHYL HYDROPEROXIDE, AND PEROXYACETIC ACID

The temperature-dependent solubilities of hydrogen peroxide (H2O2), hy droxymethyl hydroperoxide (HOCH2O2H), methyl hydroperoxide (CH3O2H), p eroxyacetic acid (CH3C(O)O2H), and ethyl hydroperoxide (C2H5O2H) were determined under conditions used in the aqueous collection and analysi s oi atmospheric hydroperoxides. Henry's law was obeyed over the sourc e concentration range employed, nominally 10(-6)-10(-2) M. Measurement s were made using either pH = 3 or pH = 6 source and collection soluti ons. The temperatures investigated ranged from 4 to 28 degrees C. A so lution pH 3 was used for experiments with H2O2, HOCH2O2H, and CH3C(O)O 2H since these compounds decompose in less acidic solution. The solubi lity of HOC2H4O2H could not be accurately determined because of its ra pid decomposition in solutions with pH > 3. The Henry's law solubility of H2O2, HOCH2O2H, CH3O2H, and CH3C(O)O2H are in agreement with prior determinations. The solubility measurement of C2H5O2H is the first of its kind. Dimensional Henry's law constants (M/atm) can be expressed by In(K-h) = A/T - B, where Tis in degrees kelvin. K-h at 25 degrees C and the A and B coefficients are [GRAPHICS] The high solubility of HO CH2O2H implies it will be efficiently removed from the atmosphere by p recipitation or surface deposition. Its decomposition and that of HOC2 H4O2H and CH3C(O)O2H forming H2O2 near neutral pH suggest these hydrop eroxides may constitute a heterogeneous source of H2O2 in atmospheric water if they are formed in the troposphere. The solubility of the lis ted organic hydroperoxides and the propensity of three of them to deco mpose at neutral pH further underscores the potential for interference 's and artifacts in the aqueous collection and nonspecific analysis of H2O2 in the atmosphere.