Detection of methylquinoline transformation products in microcosm experiments and in tar oil contaminated groundwater using LC-NMR.

N-heterocyclic compounds are known pollutants at tar oil contaminated sites. Here we report the degradation of methyl-, and hydroxy-methyl-substituted quinolines under nitrate-, sulfate- and iron-reducing conditions in microcosms with aquifer material of a former coke manufacturing site. Comparison of degradation potential and rate under different redox conditions revealed highest degradation activities under sulfate-reducing conditions, the prevailing conditions in the field. Metabolites of methylquinolines, with the exception of 2-methylquinolines, were formed in high amounts in the microcosms and could be identified by (1)H NMR spectroscopy as 2(1H)-quinolinone analogues. 4-Methyl-, 6-methyl-, and 7-methyl-3,4-dihydro-2(1H)-quinolinone, the hydrogenated metabolites in the degradation of quinoline compounds, were identified by high resolution LC-MS. Metabolites of methylquinolines showed persistence, although for the first time a transformation of 4-methylquinoline and its metabolite 4-methyl-2(1H)-quinolinone is described. The relevance of the identified metabolites is supported by the detection of a broad spectrum of them in groundwater of the field site using LC-NMR technique. LC-NMR allowed the differentiation of isomers and identification without reference compounds. A variety of methylated 2(1H)-quinolinones, as well as methyl-3,4-dihydro-2(1H)-quinolinone isomers were not identified before in groundwater.

Quantitative 1H NMR-analysis of technical octabrominated diphenylether DE-79 and UV spectra of its components and photolytic transformation products.

A quantitative analysis of the technical octabromo diphenylether mixture DE-79 is performed by (1)H NMR, avoiding any separation technique. The mass fractions are 36% BDE183, 19% BDE197, 13.1% BDE207, 9.1% BDE196, 7.3% BDE153, 6.2% BDE203, 2.2% BDE180, 1.6% BDE171, 1.2% BDE154 and 0.7% BDE206, considering an additional mass fraction of 1.3% BDE209 determined by HPLC analysis with a diode array detector (DAD). HPLC chromatograms of the BDEs in commercial decaBDE, octaBDE DE-79 and pentaBDE DE-71 and UV spectra of the components of DE-79 are presented. The photolysis of the octaBDE mixture DE-79, dissolved in tetrahydrofuran, by simulated sunlight is monitored by HPLC-DAD and observed to proceed mainly via debromination. Polybrominated dibenzofurans are identified from their UV spectra as significant intermediates.

Even-electron ions: a systematic study of the neutral species lost in the dissociation of quasi-molecular ions.

The collision-induced dissociations of the even-electron [M + H](+) and/or [M - H](-) ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH(3), SO(3)H in the negative ion mode, or NO(2) in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH(2) in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H](+) and [M - H](-) ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even-electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data and ab initio calculations at the CBS-QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even-electron [M + H](+) and/or [M - H](-) ions (generated by ESI or APCI) with that of the corresponding odd-electron [M](+) ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common product ion.

Solvent Transfer-Efficiency of Risk Management Measures.

A series of laboratory simulations were conducted in order to determine the airborne protection that might be afforded by different combinations of workplace exposure controls typically encountered when handling volatile solvents (e.g. solvent transfer). These conditions, referred to as risk management measures (RMMs) under the Registration, Evaluation and Authorisation of Chemicals Regulation (REACH), are typically described using standard phrases in safety data sheets [and specifically those of the European Phrase Catalogue (EUPhraC)]. Ethanol was used as a model compound and its emissions were monitored continuously with a portable IR spectrometer at 3000 cm-1. The average emission reduction performance of the investigated RMMs (e.g. containment, extract ventilation, drum pump) exceeded 90%. They present suitable ways to reduce airborne solvent exposure in a workplace and confirmed the initial expectations derived at by the European Solvents Industry Group (ESIG) and the European Centre For Ecotoxicology and toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) model.

Structure elucidation of phase II metabolites by tandem mass spectrometry: an overview.

The present paper provides a summary of the collision-induced dissociation of protonated and deprotonated phase II metabolites of drugs and pesticides. This overview is based on published literature and unpublished data from the authors. In particular, glutathione conjugates and their biotransformation products are discussed in detail. In addition, the fragmentation of the major classes of conjugates, i.e. glucuronides, glucosides, malonylglucosides, sulfates, acetates, methyl and glycine conjugates, is reported. Collision-induced dissociation, as studied by tandem mass spectrometry, allows the rapid identification of the type of conjugate, whereas the exact conjugation site can in general be determined only by additional NMR experiments.

Unusual polar metabolites in the groundwater of a contaminated waste site indicate a new pathway of mononitrotoluene transformation.

At a mononitrotoluene-contaminated waste disposal site, the groundwater was screened for polar transformation products of mononitrotoluenes, by means of HPLC-MS, HPLC-NMR and further off-line NMR and MS techniques. Besides expected metabolites such as aminotoluenes (ATs) and nitrobenzoic acids (NBAs), three unknowns (di- and tetrahydro-derivatives of (2-oxo-quinolin-3-yl) acetic acid) could be identified which, in the context of explosives and related compounds, are new metabolites. Evidence could be provided by microcosm experiments with 2-nitrotoluene (2-NT) that these metabolites are microbial transformation products of 2-NT under anaerobic conditions. The NMR and MS data are presented and the possible pathway for the formation of these metabolites after addition of 2-NT to fumarate is discussed.

Identification of highly polar nitroaromatic compounds in leachate and ground water samples from a TNT-contaminated waste site by LC-MS, LC-NMR, and off-line NMR and MS investigations.

Leachate and ground water samples from a trinitrotoluene-contaminated waste disposal site near a former ammunitions plant in Stadtallendorf, Germany, were analyzed by liquid chromatography (LC)-mass spectrometry (MS) and LC-NMR hyphenated techniques to comprehensively characterize the range of highly polar nitroaromatic compounds. Wherever unknown components could not be identified by comparison with a multistandard, the spectroscopic data obtained on-line were used to make initial structure proposals, which were later confirmed by comparison with authentic reference materials. In those cases where reference materials were not commercially available, unknown compounds were isolated by HPLC cuts and their structures were elucidated by off-line NMR and MS investigations. A variety of previously unknown compounds, including nitrophenols, nitrobenzyl alcohols, methylnitrobenzoic acids, and hydroxynitrobenzoic acids, could be identified. The NMR and MS data are presented here. The main polar compounds were additionally quantified.

Analysis of highly polar compounds in groundwater samples from ammunition waste sites. Part I-Characterization of the pollutant spectrum.

Five groundwater samples from the former ammunition production site at Elsnig, Germany, were analyzed for highly polar components by LC-NMR and LC-MS. A variety of unknown pollutants could be identified. Possibilities and limitations of the combined use of LC-NMR and LC-MS techniques for on-line identification are discussed. Further unknown components were identified through isolation by HPLC cuts and off-line NMR and MS investigations. Most of the polar compounds in the investigated samples could also be quantified.