Method for the Collection and HPLC Analysis of Hydrogen Peroxide and C\u3csub\u3el\u3c/sub\u3e and C\u3csub\u3e2\u3c/sub\u3e Hydroperoxides in the Atmosphere

An HPLC (high-performance liquid chromatography) method was developed to quantify hydrogen peroxide, methyl hydroperoxide. Hydroxymethyl hydroperoxide, ethyl hydroperoxide, and peroxyaectic acid in the atmosphere. Gas-phase hydroperoxides are collected in aqueous solution using a continuous-flow glass scrubbing coil and then analyzed by an HPLC postcolumn derivatization system. The detection system is based on fluorescence, produced by the product of the reaction of hydroperoxides with peroxidase and p-hydroxyphenylacetic acid. Reproducibilities are better than 3% for all hydroperoxides in aqueous concentrations of 1 × 10−7–6 × 10−7 M. Detection limits in aqueous concentration are 1.2 × 10−9 M for hydrogen peroxide, 1.5 × 10−9 M for hydroxymethyl hydroperoxide, 2.9 × 10−9 M for methyl hydroperoxide, 16 × 10−9 M for peroxyaectic acid, and 19 × 10−9 M for ethyl hydroperoxide. Corresponding gas-phase detection limits are 5 PPtv for hydrogen peroxide, 7 pptv for hydroxymethyl hydroperoxide, 13 pptv for methyl hydroperoxide, 72 pptv for peroxyacetic acid, and 84 pptv for ethyl hydroperoxide for an air sample flow rate of two standard liters per minute and collection solution flow rate of 4 × 10−4 L min−1. The gas-phase detection limits for the latter three hydroperoxides vary depending on temperature, pressure, air sample flow rate, and collection solution flow rate. This system was used for several airborne and ground measurements and showed reliable performance

Henry\u27s law constant determinations for hydrogen peroxide, methyl hydroperoxide, hydroxymethyl hydroperoxide, ethyl hydroperoxide, and peroxyacetic acid

The temperature-dependent solubilities of hydrogen peroxide (H2O2), hydroxymethyl hydroperoxide (HOCH2O2H), methyl hydroperoxide (CH3O2H), peroxyacetic acid (CH3C(O)O2H), and ethyl hydroperoxide (C2H5O2H) were determined under conditions used in the aqueous collection and analysis of atmospheric hydroperoxides. Henry\u27s law was obeyed over the source concentration range employed, nominally 10-6-10-2 M. Measurements were made using either pH = 3 or pH = 6 source and collection solutions. The temperatures investigated ranged from 4 to 28°C. A solution pH 3 was used for experiments with H2O2, HOCH2O2H, and CH3C(O)O2H since these compounds decompose in less acidic solution. The solubility of HOC2H4O2H could not be accurately determined because of its rapid decomposition in solutions with pH \u3e 3. The Henry\u27s 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\u27s law constants (M/atm) can be expressed by ln(Kh) = A/T - B, where T is in degrees kelvin. Kh at 25°C and the A and B coefficients are compound A B Kh (M atm-1) H2O2 7379 ± 156 13.42 ± 0.54 8.33 × 104 ± 3.8 × 103 CH3O2H 5241 ± 133 11.84 ± 0.46 311 ± 14 HOCH2O2H 9652 ± 53 18.04 ± 0.18 1.67 × 106 ± 3.5 × 105 CH3C(O)O2H 5308 ± 672 11.07 ± 2.34 837 ± 175 C2H5O2H 5995 ± 200 14.28 ± 0.70 336 ± 20 The high solubility of HOCH2O2H implies it will be efficiently removed from the atmosphere by precipitation or surface deposition. Its decomposition and that of HOC2H4O2H and CH3C(O)O2H forming H2O2 near neutral pH suggest these hydroperoxides may constitute a heterogeneous source of H2O2 in atmospheric water if they are formed in the troposphere. The solubility of the listed organic hydroperoxides and the propensity of three of them to decompose at neutral pH further underscores the potential for interference\u27s and artifacts in the aqueous collection and nonspecific analysis of H2O2 in the atmosphere. © 1996 American Chemical Society