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Proton affinities of n-alkylamines, n-alkyl thiols, n-alcohols and the ammonium affinities of n-alcohols up to C-18 were calculated and they were all found to be co-relating linearly. The calculated PA's make it clear that NH3 is an appropriate reactant gas for the formation of the so-called 'quasi-molecular ions' of thiols and alcohols in CIMS.

Abstract: For the first time, a study has been made of H2S as a reactant gas in positive-ion chemical-ionization mass spectrometry. To this end, the mass spectrum of an H2S plasma was recorded, and the energies and structures of the ions were examined. The most stable structures of the plasma ions H3S+, S2 +, H2S2 +, H3S2 +, [H2S···H3S]+, H2S3 +, H3S4 + and HS n + were obtained by the ab initio G3B3 method, in which the G3 method is extended with B3LYP/6-31G(d). Of the three isomers of H2S3 +, the C 2V structure, with terminal hydrogen atoms, proved to be the lowest energy. The structure of the adduct [H2S···H3S]+ was found to be comparable with that of the water adduct [H2O···H3O]+. An enthalpy of −59.9kJmol−1 was calculated for the reaction H3S+ +H2S→[H2S···H3S]+ and the exothermic reaction enthalpies of the polysulfonium ions, formed according to the equation HS n + +S→HS n+1 +, lie in the range 225–347kJmol−1 for n =1–8. [Copyright &y& Elsevier]

The title compound, C20H19F3N2O4, crystallizes with two mol­ecules in the asymmetric unit. The important characteristics of the mol­ecule are the two C=N bonds in Z,E configuration, one in the β-methoxy-system and the other in the oxy­methyl side chain between the two aromatic rings. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C20H19F3N2O4, contains one mol­ecule in the asymmetric unit. The CF3 group is disordered over two positions. The important characteristics of the mol­ecule are the two C=N bonds in an E,Z-configuration, viz. E in the β-methoxy system and Z in the oxymethyl chain between the two aromatic rings. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, C19H17F3N2O4, a metabolite of the fungicide trifloxy­strobin (TFS), contains one mol­ecule in the asymmetric unit. The CF3 group is disordered over two positions. The important characteristics of the mol­ecule are the two C=N bonds in an E,E configuration, one in the β-methoxy system and the other in the oxy­methyl side chain between the two aromatic rings. The mol­ecules are linked via an O—H⋯N hydrogen bond and an infinite spiral is formed along the b-axis direction. [ABSTRACT FROM AUTHOR]

An analytical method is reported for residue analysis of the fungicide meptyldinocap in different fruit matrixes that involves extraction with ethyl acetate, hydrolysis of the residues with ethanolamine, and determination by LC/MS/MS. The method involves extraction of 10 g sample with 10 mL ethyl acetate; evaporation of the ethyl acetate phase to dryness, and subsequent hydrolysis of the residues to 4,6-dinitro-2-(1-methylheptyl) phenol on reaction with 1% ethanolamine. The pH of this hydrolyzed product was neutralized with formic acid and analyzed by LC/MS/MS. The hydrolysis reaction followed pseudo-first-order kinetics, and the reaction product was spectroscopically confirmed as 2-(1-methylheptyl)-4,6-dinitrophenol. The method offered > 80% recoveries at an LOQ of 10 ng/g for grape and mango, 25 ng/g for pomegranate with intralaboratory Horwitz ratio < 0.5, and measurement uncertainties < 10% at LOQ levels. Considering first-order rate kinetics, activation energy, enthalpy of activation, and entropy of activation varied as solvent > mango > grape > pomegranate. Free energy of activation at 298 K was higher than at 280 K and was similar for solvent and three matrixes at both temperatures.

A multimethod based on liquid-liquid extraction and solid-liquid extraction for the analysis of persistent organic pollutants in water and sludge from sewage treatment plants has been established. Traces of 22 organic compounds used in industry and personal care products (PCPs) were analyzed by GC/MS. The LODs for the analytes were less than 2.3 ng/L for wastewater and 31 microg/kg (dry weight matter) for sewage sludge. Satisfactory recoveries (70-130%) were achieved. The validated method permits the analysis of water and sludge samples at various stages of the treatment from different sewage treatment plants. Thus, the distribution between water and sludge as well as the dissipation of the compounds analyzed were balanced. By this means, the efficiency of different wastewater treatment plants (WWTPs) can be evaluated and measures can be taken to optimize the treatment process at different stages.

In vitro biodegradation of trifloxystrobin (TFS) under darkness could best be explained by two-compartment first + first-order rate kinetics with half-lives ranging between 1.8 and 2.3 days. Hydrolysis was found to be the major pathway of degradation resulting in the formation of the acid metabolite, TFS-acid, with an EE conformation. The adsorption rate kinetics of both TFS and TFS-acid followed linear and Freundlich isotherms. The extent of adsorption was directly correlated with organic matter and clay contents, whereas desorption had a negative correlation. The high partition coefficients (KD) indicate strong adsorption of TFS on all of the test soils without any appreciable risk of groundwater contamination. In case of the TFS-acid, however, the adsorption was weaker; hence, if its further degradation is slow, it may contaminate lower soil horizons under worst case conditions. TFS did not cause any adverse effect on the soil microbial population. TFS was susceptible to aquatic photolysis in summer with an environmental half-life of 0.7-1.3 days irrespective of the latitudes.