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Abstract. Gas-phase H 2 O 2 , organic peroxides and carbonyl compounds were determined at various sites from Mid-July to early August 1998 during the BERLIOZ campaign in Germany. The sites were located northwest of Berlin and were chosen to determine pollutants downwind of the city emissions during a summer smog episode. Hydrogen peroxide (H 2 O 2 ), methyl hydroperoxide (MHP, CH 3 OOH) and occasionally hydroxymethyl hydroperoxide (HMHP, HOCH 2 OOH) were quantified in air samples by commercial fluorimetric methods and classical HPLC with post-column derivatisation by horseradish peroxidase/p-hydroxyphenyl acetic acid and fluorimetric detection. Carbonyl compounds were determined in ambient air by a novel method based on O-pentafluorobenzyl hydroxylamine as derivatisation agent. Mixing ratio profiles of the hydroperoxides and the carbonyl compounds are reported for the intensive phase of the campaign, 20-21 July, 1998. Peroxides showed pronounced diurnal variations with peak mixing ratios in the early afternoon. At times, a second maximum was observed in the late afternoon. The major part of the H 2 O 2 was formed through recombination reactions of HO 2 radicals, but there is some evidence that H 2 O 2 is also formed from ozonolysis of anthropogenic and/or biogenic alkenes. Diurnal variations of mixing ratios of various carbonyl compounds are reported: alkanals (C 2 to C 10 , isobutanal), unsaturated carbonyl compounds (methacrolein, methylvinylketone, acrolein), hydroxycarbonyl (glycolaldehyde, hydroxyacetone) and dicarbonyl compounds (glyoxal, methylglyoxal, biacetyl), aromatic compounds (benzaldehyde, o-and m-tolylaldehyde) and pinonaldehyde.

Four geometric isomers of trifloxystrobin (TFS)--namely EE, EZ, ZE, and ZZ--were hydrolyzed by 0.05 M NaOH, resulting in four corresponding acid metabolites. These compounds--namely EE-, EZ-, ZE-, and ZZ-acids--were purified by preparative HPLC and authentically characterized by a combination of infrared, Raman, GC-MS, LC-MS/MS, and NMR spectroscopies. The spectra were found to be very characteristic of the individual isomers, and so they could be used to distinguish the isomers from each other. The detailed spectral features of the individual isomers are presented and compared. EE-acid was identified as being the major metabolite of TFS in soil, which indicates that hydrolysis is the principal route of degradation of TFS. This finding further justifies the importance of the present study in relation to assessing the risk associated with the release of TFS into the environment.

The B3LYP/6-31+G(d,p) method was used to calculate the proton affinities of n-alkylamines, n-alkyl thiols, and n-alcohols and the ammonium affinities of the n-alcohols up to C-18. These affinities and the gas-phase acidities of the n-alcohols were all found to correlate linearly with the quotient n/(n + 1), where n is the number of carbon atoms in the alkyl chain. This correlation leads to a limiting value of ∆H for very long alkyl chains: for the amines, thiols, and alcohols, the calculated maximum proton affinities PA 298,max (RX) were 938.7, 828.2, and 816.9 kJ mol -1 , respectively. The maximum ammonium affinity, -∆H 298,max , of the n-alcohols is 115.1 kJ mol -1 .

The photoisomerization kinetics of trifloxystrobin (TFS) in acetone under artificial sunlight is reported. HPLC analysis showed the TFS, a strobilurine fungicide of EE conformation, was converted into an equilibrium mixture of four isomers after illumination for 7 h. The isomers were identified as EZ, EE, ZZ, and ZE and were separated in the crystalline form by preparative HPLC and characterized by use of a variety of spectroscopic techniques. The quantum yield and reaction constants for the isomerization reactions were determined. The detailed spectral features of the individual isomers measured by UV, IR, Raman, NMR and mass spectroscopy are presented and compared. The spectra of the isomers were found to be very characteristic, with good analytical significance.