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RATIONALE In aqueous samples compound-specific stable isotope analysis (CSIA) plays an important role. No direct method (without sample preparation) for stable nitrogen isotope analysis (δ(15) N SIA) of non-volatile compounds is known yet. The development of a novel HPLC/IRMS interface based on high-temperature combustion (HTC) for both δ(13) C and δ(15) N CSIA and its proof of principle are described in this study. METHODS To hyphenate high-performance liquid chromatography (HPLC) with isotope ratio mass spectrometry (IRMS) a modified high-temperature combustion total organic carbon analyzer (HTC TOC) was used. A system to handle a continuously large amount of water (three-step drying system), favorable carrier and reaction gas mix and flow, an efficient high-temperature-based oxidation and subsequent reduction system and a collimated beam transfer system were the main requirements to achieve the necessary performance. RESULTS The proof of principle with caffeine solutions of the system succeeded. In this initial testing, both δ(13) C and δ(15) N values of tested compounds were determined with precision and trueness of ≤0.5 ‰. Further tests resulted in lower working limit values of 3.5 μgC for δ(13) C SIA and 20 μgN for δ(15) N SIA, considering an accuracy of ±0.5 ‰ as acceptable. CONCLUSIONS The development of a novel HPLC/IRMS interface resulted in the first system reported to be suitable for both δ(13) C and δ(15) N direct CSIA of non-volatile compounds. This highly efficient system will probably open up new possibilities in SIA-based research fields. Copyright © 2016 John Wiley & Sons, Ltd.

Rationale Compound-specific isotope analysis (CSIA) of persistent organic contaminants can be used for source apportioning in the environment if appropriate sensitivity can be achieved. This paper describes the optimization and validation of a sensitive analytical approach for the determination of the carbon isotope composition of semi-volatile organic compounds, such as polycyclic aromatic hydrocarbons (PAHs). Methods Analyses are based on the introduction of up to 150 μL of organic extracts by means of programmed temperature vaporization-large-volume injection combined with gas chromatography coupled to isotope ratio mass spectrometry (PTV-LVI-GC/IRMS). To allow for the analysis of more volatile, low-molecular-weight PAHs, the PTV injector was equipped with a sub-ambient/cryogenic cooling. Accuracy, precision, linearity and determination limits for application in isotope analysis were evaluated for a set of individual PAHs ranging from two- to five-ring molecular structures. The method was exemplified by determining the δ(13) C values of individual PAHs in soil samples in a source apportionment study at a contaminated site. Results The choice of PTV injection parameters is crucial to prevent isotope fractionation during injection and largely depends on the analytes to be determined. The observed isotope fractionation effect on semi-volatiles depends on the applied solvent and injection temperature and demonstrates the importance of performing appropriate tests with given PTV parameters for each of the compounds of interest. The proposed PTV-LVI-GC/IRMS method allows the carbon isotope ratio (δ(13) C value) of individual PAHs to be determined accurately and precisely at concentrations of 0.04-0.1 ng μL(-1) even for volatile PAHs such as naphthalene or acenaphthene. Conclusions LVI with PTV injector cooling allows for the isotopic analysis of volatile and semi-volatile PAHs at trace concentrations, thus considerably expanding the applicability of CSIA in environmental studies.

Microwave-assisted ionic liquid extraction (MAILE) has been investigated for the extraction of n-alkanes and isoprenoid hydrocarbons from petroleum source rock and the conditions for maximum yield of the analytes were determined. An aqueous solution of an ionic liquid, 1-butyl-3-methylimidazolium bromide (BmimBr), was employed as the extracting medium. The results showed that the concentration of ionic liquid, extraction time and extraction temperatures have effects on extraction yields of aliphatic hydrocarbons with optimal conditions at: 3.0 mol L−1 ionic liquid solution, 30 min and 120 °C, respectively. The extraction yields of all the n-alkanes and acyclic isoprenoid hydrocarbons were much higher using microwave-assisted ionic liquid extraction than with Soxhlet extraction and accelerated solvent extraction. There were good correlations of the diagnostic geochemical ratios calculated from the gas chromatographic (GC) data of MAILE, Soxhlet extraction and accelerated solvent extraction. The results of this study show that MAILE is an efficient and green analytical preparatory technique for geochemical evaluation of petroleum source rock.

Multifunctional ionic liquid monomer (1) was synthesized from 1-vinylimidazole and 2-acrylamido-2-methylpropane sulphonic acid (AMPS) and alternately copolymerized from 3-mercaptopropyltrimethoxysilane grafted silica core (2) to obtain hybrid core-shell particles Sil-PIL.1. Elemental analysis and 13C CP/MAS results confirmed that the ionic monomers retained the alternation after grafting on silica surface, which make it a promising candidate as sorbent for trapping analytes from aqueous and other samples for solventless microextraction processes. The material demonstrated excellent extraction efficiency for low molecular weight polar compounds and the peak areas for derivatized aldehydes can be increased up to 200 times in comparison with a commercial polydimethylsiloxane (PDMS) sorbent.

The environmental micropollutant sulfamethoxazole (SMX) is susceptible to phototransformation by sunlight and UV-C light which is used for water disinfection. Depending on the environmental pH conditions SMX may be present as neutral or anionic species. This study systematically investigates the phototransformation of these two relevant SMX species using four different irradiation scenarios, i.e., a low, medium, and high pressure Hg lamp and simulated sunlight. The observed phototransformation kinetics are complemented by data from compound-specific stable isotope and transformation product analysis using isotope-ratio and high-resolution mass spectrometry (HRMS). Observed phototransformation kinetics were faster for the neutral than for the anionic SMX species (from 3.4 (LP lamp) up to 6.6 (HP lamp) times). Furthermore, four phototransformation products (with m/z 189, 202, 242, and 260) were detected by HRMS that have not yet been described for direct photolysis of SMX. Isotopic fractionation occurred only if UV-B and UV-A wavelengths prevailed in the emitted irradiation and was most pronounced for the neutral species with simulated sunlight (ε

This study reports number, size and color distribution, and metal contents of microplastics as well as adherent sediments along the Persian Gulf. Samples were collected from 9 stations in summer 2015 with a sampling time interval of 10 days. Plastic size of 2–5 mm, and ≤0.25 mm with 45 and 33% and white and colorless plastics with 62 and 33% had the highest abundance considering number per m2, respectively. In general, the majority of collected plastics (79%) were smaller than 5 mm (defined size for microplastics). The mean Al, Fe, Mn, Cd, Cr, Ni, Pb, Cu contents of plastic fragments were 115, 531, 32.2, 0.035, 0.915, 2.03, 4.59, and 3.6 μg g−1, respectively while the mean Al, Fe, Mn, Cd, Cr, Ni, Pb, Cu contents of sediments were 186, 3050, 127, 0.81, 5.01, 14.5, 48.6 and 5.43 μg g−1 respectively. There were significant differences between the abundance of plastic items as well as the all examined metal concentrations of microplastics and sediments at different sampling times. As there is no regular cleanup program in the studied areas, significant differences between plastic items number at different sampling times (with higher plastic items number at the first day of sampling) showed that a large number of plastic items may enter from beaches to the sea and become available to marine organisms.

The release of antibiotics into the environment may lead to deleterious effects in non-target organisms as well as pressure in antimicrobial resistance acquirement. Ceftiofur (CEF) and cefapirin (CEPA) are veterinary cephalosporins used for recurrent and economically relevant infections. Both antibiotics have been detected in aquatic environments and their fate during drinking water processing is still unknown. This work investigated the acute and chronic toxicities of CEF and CEPA towards aquatic organisms including stability tests. Complementary, the effects of water disinfection radiation (UV-C, 254nm) on ecotoxicological responses were studied. CEF and CEPA have significant decay during Daphnia magna tests, portraying half-lives (t1/2) of 49 and 53h, respectively. During tests with green algae (Scenedesmus spec.), CEPA was more instable (t1/2 88h) than CEF (t1/2 267h). CEF and its presumable hydrolysis products induced deleterious effects in Daphnia magna (48h EC50 139, LC50 179 in μM), which was not observed with Scenedesmus spec. (72h NOAEC 82.5±2.5μM). In the case of CEPA, no toxic effects were observed in either test (48h EC-LC50>510 and 72h NOAEC 57±6, in μM). Photolysis of CEPA resulted in toxic products, which were effective for the cladoceran but not for the green algae. On the other hand, the different radiation doses studied did not affect CEF ecotoxicity. This investigation illustrates the importance of cephalosporin hydrolysis during standard toxicity tests. Furthermore, the potential formation of species-specific toxic compounds during water processing is demonstrated, highlighting the need of further assessing toxicity of both cephalosporins and their transformation products.

Since 2004, when microplastics appears in literature, thousands of researchers focussed on this topic and analysed microplastics in almost every environmental compartment. However, there is still a lack of standardisation, and therefore, used methodologies varied widely. Most researchers performed controversially discussed visual examination, but it became more and more a supporting tool to reduce measuring effort. To that account, especially infrared or Raman microscopy were used for chemical characterisation. This indicates that dimensions of analysed microplastics changed to micrometre scaling. However, those microscopy technologies were used for particle by particle characterisation, and therefore, it is still challenging to handle the mass of data. Alternatively, thermal extraction and desorption gas chromatography is a useful integrating analysis approach, which allows a multicomponent characterisation of environmental samples without any complex sample preparation.

Perfluorinated organic compounds (PFC) are an important group of pollutants, which are difficult to be degraded in conventional water treatment. Even hydroxyl radical based processes are not capable to degrade these compounds. Sulfate radicals can oxidize a group of PFC, i.e., perfluorinated carboxylic (PFCAs) acids. However, information in literature on kinetics and reaction mechanism is largely based on model simulations which are prone to errors. The present study provides mechanistic insights based on product formation, material balances, competition kinetics experiments and quantum chemical calculations. Furthermore, energy requirements for sulfate radical based degradation of PFCA is evaluated in the present study. PFCAs can be partly mineralized in chain reactions initiated by sulfate radicals (SO4 ─). The perfluorinated acetic acid (TFA), propionic acid, and butanoic acid are largely degraded in a primary reaction with sulfate radicals. In case of PFCA with a chain length of > 4 carbons low yields of PFCA products were observed. Regarding reaction kinetics sulfate radicals react very slow with PFCAs (≈ 104 M−1 s−1). Thus, the energy demand required for generation of SO4 ─ by photolysis of S2O82─ (UV/S2O82−) is very high. A 90% degradation of a PFCA by UV/S2O82− was estimated to be 55 kW h m−3 in pure water.

To reduce the discharge of micropollutants, advanced wastewater treatment methods were investigated in the last years. Estrogenic effects were found to be reduced by ozonation. These activities are usually measured using genetically modified cell-based tests. As these bioassays are representing a sum parameter, also inhibitory effects such as antagonistic effects need to be further investigated as they are potentially reducing the detected activities. Therefore, a direct comparison of chemical target analysis and biological equivalent concentrations measured by bioassays is often difficult. To investigate the fate of antagonistic activities and their role in mixtures with agonistic activities, two hospital wastewater treatment plants were studied after different treatment steps. Thereby highly enriched samples were analyzed by a combination of bioassays with chemical target and non-target analyses. In order to achieve an in-depth characterization of the antagonistic activities a fractionation of the enriched samples was performed. To identify relevant compounds an effect directed identification approach was used by combining high-resolution mass spectrometry and bioassays. The results showed a high reduction for estrogene and androgene activities. However, a constant antagonistic activity after membrane bioreactor and ozone treatment was observed. A reduction of the antagonistic activity was observed after passing an activated carbon filter. The fractionation approach showed a specific finger-print of each sample of the different treatment steps. Hereby we could show that the composition of agonistic and antagonistic active compounds is changing after each treatment step while the overall measured activity stays the same. Using fractionation and the combination of bioassays the number of relevant features detected by chemical non-target screening could be reduced by > 85%. As a result the phosphorous flame retardant TCEP could be identified as anti-estrogene active. Future research should be done to identify more antagonistic active compounds and potentially active transformation products after ozone treatment.

The toxic metal contents of cigarette butts and distribution of cigarette butts have not been studied well in maritime environment. In the present study, cigarette butts distribution and the associations of Hg and Pb from cigarette butts were monitored along the Persian Gulf with 10 days interval sampling time. The number of cigarette butts, and Hg and Pb associations of butts were found to vary widely between 2 and 38 items per square meter, 2.5 and 86.32 ng/g cigarette butt (CB), as well as 650 and 8630 ng/g CB, respectively. Wilcoxon signed-rank test showed that there were no significant differences between the number of butts, and Hg and Pb contents of the butts at different sampling times. Considering amount of cigarette butts littered yearly, this study demonstrates that remarkable toxic metals of Hg and Pb may enter maritime environment each year and may introduce critical hazards to aquatic organisms, enter food chain, and finally human body.

The sugar replacement compound xylitol has gained increasing attention because of its use in many commercial food products, dental-hygiene articles, and pharmaceuticals. It can be classified by the origin of the raw material used for its production. The traditional “birch xylitol” is considered a premium product, in contrast to xylitol produced from agriculture byproducts such as corn husks or sugar-cane straw. Bulk stable-isotope analysis (BSIA) and compound-specific stable-isotope analysis (CSIA) by liquid-chromatography isotope-ratio mass spectrometry (LC-IRMS) of chewing-gum extracts were used to determine the δ13C isotope signatures for xylitol. These were applied to elucidate the original plant type the xylitol was produced from on the basis of differences in isotope-fractionation processes of photosynthetic CO2 fixation. For the LC-IRMS analysis, an organic-solvent-free extraction protocol and HPLC method for the separation of xylitol from different artificial sweeteners and sugar-replacement compo...

Atrazine, propazine, and terbuthylazine are chlorotriazine herbicides that have been frequently used in agriculture and thus are potential drinking water contaminants. Hydroxyl radicals produced by advanced oxidation processes can degrade these persistent compounds. These herbicides are also very reactive with sulfate radicals (2.2-3.5 × 10(9) M(-1) s(-1)). However, the dealkylated products of chlorotriazine pesticides are less reactive toward sulfate radicals (e.g., desethyl-desisopropyl-atrazine (DEDIA; 1.5 × 10(8) M(-1) s(-1))). The high reactivity of the herbicides is largely due to the ethyl or isopropyl group. For example, desisopropyl-atrazine (DIA) reacts quickly (k = 2 × 10(9) M(-1) s(-1)), whereas desethyl-atrazine (DEA) reacts more slowly (k = 9.6 × 10(8) M(-1) s(-1)). The tert-butyl group does not have a strong effect on reaction rate, as shown by the similar second order reaction rates between desethyl-terbuthylazine (DET; k = 3.6 × 10(8) M(-1) s(-1)) and DEDIA. Sulfate radicals degrade a significant proportion of atrazine (63%) via dealkylation, in which deethylation significantly dominates over deisopropylation (10:1). Sulfate and hydroxyl radicals react at an equally fast rate with atrazine (k (hydroxyl radical + atrazine) = 3 × 10(9) M(-1) s(-1)). However, sulfate and hydroxyl radicals differ considerably in their reaction rates with humic acids (k (sulfate radical + humic acids) = 6.8 × 10(3) L mgC(-1) s(-1) (mgC = mg carbon); k (hydroxyl radical + humic acids) = 1.4 × 10(4) L mgC(-1) s(-1)). Thus, in the presence of humic acids, atrazine is degraded more efficiently by sulfate radicals than by hydroxyl radicals.

The interest in two-dimensional liquid chromatography separations is growing every year together with the number of open questions on the benefits of multidimensional systems in comparison to one-dimensional liquid chromatography. In order to solve some of these open questions this work presents a comparison of one-dimensional and microscale two-dimensional liquid chromatography coupled to high resolution mass spectrometry for targeted analysis in wastewater. The comparison is based on the evaluation of a reference standard mixture containing 99 compounds and a real wastewater sample. For the evaluation and compound identification three different criteria were chosen. At first, a deviation of ±5 ppm from the exact mass was defined as acceptable to include the compound for further evaluation. To eliminate false positive results, a maximum retention time deviation of less than 2.5% for each compound of the reference standard and the compounds detected in the wastewater sample was defined for a positive identification as a second criterion for 1D-LC and the second dimension of 2D-LC. In the third step, fragment information from MS/MS experiments was used for further identification of compounds in wastewater. Additionally, the influence of a higher mass accuracy of 1 ppm on the number of identified compounds in comparison to a mass accuracy of 5 ppm was investigated. The results showed that the number of identified compounds was higher by a factor of three in the wastewater sample when using the microscale 2D-LC approach. Moreover, a higher reliability for compound identification is obtained when using retention time and MS/MS information as identification criteria instead of only applying high mass accuracy of 1 or 5 ppm.

The Fenton reaction describes the reaction of Fe(II) with hydrogen peroxide. Several researchers proposed the formation of an intermediate iron-peroxo-complex but experimental evidence for its existence is still missing. The present study investigates formation and life time of this intermediate at various conditions such as different Fe(II)-concentrations, absence vs. presence of a hydroxyl radical scavenger (dimethylsulfoxide, DMSO), and different pH values. Obtained results indicate that the iron-peroxo-complex is formed under all experimental conditions. Based on these data, stability of the iron-peroxo-complex could be examined. At pH 3 regardless of [Fe(II)] 0 decay rates for the iron-peroxo-complex of about 50 s - 1 were determined in absence and presence of DMSO. Without DMSO and [Fe(II)] 0 = 300 µM variation of pH yielded decay rates of about 70 s - 1 for pH 1 and 2 and of about 50 s - 1 at pH 3 and 4. Hence, the iron-peroxo-complex becomes more stable ...

RATIONALE The concentration-gradient-method (CGM) was previously introduced as a precise and accurate method for isotope ratio determination by quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The investigation of its potential and advantages in the analysis of analytes with a poor signal-noise ratio (S/N) is important to establish routine isotope ratio analysis industrial applications on these widely used instruments. METHODS The CGM was applied on isotope measurements of Sr near its limit of quantification (LOQ) and of sulphur where there was a massively interfered 32 S isotope signal in gypsum samples of different origin, in order to demonstrate the advantages of the CGM over the commonly used measurement and evaluation approach. The comparison between the CGM and the classical measurement and evaluation approach was performed with high and low concentration Sr standard solutions, to prove the robustness of the isotope ratio determination. RESULTS In both cases the CGM reached a recovery rate of approximately 103 %, whereas the classical approach became increasingly inaccurate at lower S/N (recovery of 123 %). In the case of sulphur isotope ratio determination only the CGM enabled a differentiation between geogenic and flue gas desulphurisation plant-originated gypsum samples. CONCLUSIONS The robustness of the CGM approach was illustrated for gypsum samples with trace strontium concentration and its general applicability to the determination of sulphur isotope ratios by means of quadrupole-based ICP-MS was demonstrated using the example of sulphur in gypsum.

One key step studying interactions of microplastics with our ecological system is to identify plastics within environmental samples. Aging processes and surface contamination especially with biofilms impede this characterization. A complex and time-consuming cleaning procedure is a common solution for this problem. However, it implies an artificial change of sample composition with a risk of losing important information or even damaging microplastic particles. In the present work, we introduce a new chemometric approach to identify heavily weathered and contaminated microplastics without any cleaning. The main idea of this concept is based on an automated curve fitting of most relevant vibrational bands to calculate a highly characteristic fingerprint that contains all vibrational band area ratios. This new data set will be used to estimate the similarity of samples and reference standards for identification. A total of 300 individual naturally weathered plastic particles were measured with Fourier transformation infrared spectroscopy in attenuated total reflection mode (FT-IR ATR) and identified successfully with the new method. To that end, all samples were compared with a selection of common reference plastics and bio polymers. As it turns out, the accuracy of identification rises significantly from 76% by means of conventional library searching algorithms to 96% by identifying microplastics with our new method. Therefore, the new approach can be a useful tool to compare and describe similarities of FT-IR spectra of microplastics, which may improve further research studies on this topic.

This paper deals with reactions occurring in the aqueous system of 2-propanol/ozone. The considered reactions are discussed from thermodynamic and kinetic points of view. The major finding refers to the fact that 2-propanol reacts with O3 mainly via hydride transfer: (HO)(H3C)2C H + O3 → [(HO)(H3C)2C+ + HO3−]cage → (HO)(H3C)2C+ + HO3− → (H3C)2C O + H2O + O2 Arguments supporting this proposed mechanism are: high exergonicity of reaction (ΔG = −234 kJ mol−1 for the first two steps), low HO yield - (2.4 ± 0.5)% and high acetone yield - (87.2 ± 1.5)%. Other oxidation products detected within the system are acetaldehyde - (1.4 ± 0.1)%, formaldehyde - (4.0 ± 0.1)%, acetic acid - (2.8 ± 0.2)%, formic acid - (0.6 ± 0.2)% and hydrogen peroxide - (1.5 ± 0.1)%. The temperature dependence of the second order rate constant for the reaction 2-propanol + O3 → products is ln kII = 29.64–8500 × T−1. The activation energy and pre-exponential factor derived from this relationship are (71 ± 3) kJ mol−1 and (7.5 ± 6.4) × 1012 M−1 s−1, respectively. At 23 °C, the second order rate constant is kII = (2.7 ± 0.1) M−1 s−1. The low reaction rate can be explained by the transfer of one hydride ion from 2-propanol to electrophilic ozone.

Biological methane oxidation may be regarded as a method of aftercare treatment for landfills to reduce climate relevant methane emissions. It is of social and economic interest to estimate the behavior of bacterial methane oxidation in aged landfill covers due to an adequate long-term treatment of the gas emissions. Different approaches assessing methane oxidation in laboratory column studies have been investigated by other authors recently. However, this work represents the first study in which three independent approaches, ((i) mass balance, (ii) stable isotope analysis, and (iii) stoichiometric balance of product (CO2) and reactant (CH4) by CO2/CH4-ratio) have been compared for the estimation of the biodegradation by a robust statistical validation on a rectangular, wide soil column. Additionally, an evaluation by thermal imaging as a potential technique for the localization of the active zone of bacterial methane oxidation has been addressed in connection with stable isotope analysis and CO2/CH4-ratios. Although landfills can be considered as open systems the results for stable isotope analysis based on a closed system correlated better with the mass balance than calculations based on an open system. CO2/CH4-ratios were also in good agreement with mass balance. In general, highest values for biodegradation were determined from mass balance, followed by CO2/CH4-ratio, and stable isotope analysis. The investigated topsoil proved to be very suitable as a potential cover layer by removing up to 99% of methane for CH4 loads of 35-65gm-2d-1 that are typical in the aftercare phase of landfills. Finally, data from stable isotope analysis and the CO2/CH4-ratios were used to trace microbial activity within the reactor system. It was shown that methane consumption and temperature increase, as a cause of high microbial activity, correlated very well.

RATIONALE: Traditionally, dissolved organic carbon (DOC) stable isotope analysis (SIA) is performed using either offline sample preparation followed by elemental analyzer/isotope ratiomass spectrometry (EA/IRMS) or a wet chemical oxidation (WCO)-based device coupled to an isotope ratio mass spectrometer. The first method is time-consuming and laborious. The second involves the risks of underestimation of DOC concentration and isotopic fractionation due to incomplete oxidation. The development of an analytical method for accurate and sensitive DOC SIA is described in this study. METHODS: A high-temperature combustion (HTC) system improves upon traditional methods. A novel total organic carbon (TOC) system, specially designed for SIA, was coupled to an isotope ratio mass spectrometer. An integrated purge and trap technique (peak focusing), flexible injection volume (0.05-3 mL), favorable carrier gas flow, modified ash crucible, new design of combustion tube and optimized drying system were used to achieve the necessary performance. RESULTS: The system can reliably measure concentrations up to 1000 mgC/L. Compounds resistant to oxidation, such as barbituric acid, melamine and humic acid, were analyzed with recovery rates of 100 +/- 1% proving complete oxidation. In this initial testing, the delta C-13 values of these compounds were determined with precision and trueness of CONCLUSIONS: The novel HTC system coupled to an isotope ratio mass spectrometer resulted in significantly improved sensitivity. The system is suitable for salt-containing liquids and compounds that are resistant to oxidation, and it offers a large concentration range. A second paper (which follows this one in this issue) will present a more comprehensive assessment of the analytical performance with a broad set of solutions and real samples. This highly efficient TOC stable isotopic analyzer will probably open up new possibilities in biogeochemical carbon cycle research. Copyright (C) 2014 John Wiley & Sons, Ltd.

Producing valuable biochar from waste materials using thermal processes like hydrothermal carbonization (HTC) has gained attention in recent years. However, the fate of micropollutants present in these waste sources have been neglected, although they might entail the risk of environmental pollution. Thus, an HPLC-MS/MS method was developed for 12 pharmaceuticals to determine the micropollutant load of biochar, which was made from sewage sludge via HTC within 4 h at 210 °C. Pressurized liquid extraction was applied to extract the compounds. Because of the high load of co-extracted matter, matrix effects in HPLC-MS/MS were investigated using matrix effect profiles. Interfering compounds suppressed 50 % of the phenazone signal in sewage sludge and 70 % in biochar, for example. The quantification approaches external calibration, internal standard analysis, and standard addition were compared considering recovery rates, standard deviations, and measurement uncertainties. The external analysis resulted in decreased or enhanced recovery rates. Spiking before LC-MS/MS compensated instrumental matrix effects. Still, recovery rates remained below 70 % for most compounds because this approach neglects sample losses during the extraction. Internal standards compensated for the matrix effects sufficiently for up to five compounds. The standard addition over the whole procedure proved to compensate for the matrix effects for 11 compounds and achieved recovery rates between 85 and 125 %. Additionally, results showed good reproducibility and validity. Only sulfamethoxazole recovery rate remained below 70 % in sewage sludge. Real sample analysis showed that three pharmaceuticals were detected in the biochar, while the corresponding sewage sludge source contained 8 of the investigated compounds.

Sulfate radical based oxidation is discussed being a potential alternative to hydroxyl radical based oxidation for pollutant control in water treatment. However, formation of undesired by-products, has hardly been addressed in the current literature, which is an issue in other oxidative processes such as bromate formation in ozonation of bromide containing water (US-EPA and EU drinking water standard of bromate: 10 μg L(-1)). Sulfate radicals react fast with bromide (k = 3.5 × 10(9) M(-1) s(-1)) which could also yield bromate as final product. The mechanism of bromate formation in aqueous solution in presence of sulfate radicals has been investigated in the present paper. Further experiments were performed in presence of humic acids and in surface water for investigating the relevance of bromate formation in context of pollutant control. The formation of bromate by sulfate radicals resembles the well described mechanism of the hydroxyl radical based bromate formation. In both cases hypobromous acid is a requisite intermediate. In presence of organic matter formation of bromate is effectively suppressed. That can be explained by formation of superoxide formed in the reaction of sulfate radicals plus aromatic moieties of organic matter, since superoxide reduces hypobromous acid yielding bromine atoms and bromide. Hence formation of bromate can be neglected in sulfate radical based oxidation at typical conditions of water treatment.

An in-tube extraction (ITEX) method for the GC-MS analysis of volatile constituents of alcoholic beverages was developed and applied in the analysis of 46 beers from six varieties, Alt, Helles, Kolsch, Pilsener beer, Schwarzbier, and wheat beer, which are popular in Germany. The extraction performance of nine different sorbent materials was evaluated. The best overall sensitivity was achieved using Tenax TA, with method detection limits down to 0.01 μg L–1, whereas the widest linear range was possible with PDMS, covering almost 5 orders of magnitude. This is the first application of PDMS in ITEX as a high-capacity extraction device and highlights the importance of choosing the appropriate sorbent material for the analytical task at hand. A satisfying chemometric discrimination of all analyzed beer varieties was possible, and alcohol-free beers could clearly be separated from regular beers, also.

The main aim of this work is to substantiate the mechanism of 1-propanol oxidation by ozone in aqueous solution when the substrate is present in large excess. Further goals are assessment of the products, their formation yields as well as the kinetic parameters of the considered reaction. The reaction of ozone with 1-propanol in aqueous solution occurs via hydride transfer, H-abstraction and insertion. Of these three mechanisms, the largest share is for hydride transfer. This implies the extraction of an hydride ion from the activated C&minus, H group by O3 according to reaction: (C2H5)(H)(HO)C&minus, H + O3 &rarr, [(C2H5)(H)(HO)C+ + HO3&minus, ]cage &rarr, (C2H5)(H)(HO)C+ + HO3&minus, The experimentally determined products and their overall formation yields with respect to ozone are: propionaldehyde&mdash, (60 &plusmn, 3)%, propionic acid&mdash, (27.4 &plusmn, 1.0)%, acetaldehyde&mdash, (4.9 &plusmn, 0.3)%, acetic acid&mdash, (0.3 &plusmn, 0.1)%, formaldehyde&mdash, (1.0 &plusmn, 0.1)%, formic acid&mdash, (4.6 &plusmn, 0.3)%, hydrogen peroxide&mdash, (11.1 &plusmn, 0.3)% and hydroxyl radical&mdash, (9.8 &plusmn, 0.3)%. The reaction of ozone with 1-propanol in aqueous media follows a second order kinetics with a reaction rate constant of (0.64 &plusmn, 0.02) M&minus, 1&middot, s&minus, 1 at pH = 7 and 23 &deg, C. The dependence of the second order rate constant on temperature is described by the equation: l n &nbsp, k I I = ( 27.17 &plusmn, 0.38 ) &ndash, ( 8180 &plusmn, 120 ) &times, T &minus, 1 , which gives the activation energy, Ea = (68 &plusmn, 1) kJ mol&minus, 1 and pre-exponential factor, A = (6.3 &plusmn, 2.4) &times, 1011 M&minus, 1 s&minus, 1. The nature of products, their yields and the kinetic data can be used in water treatment. The fact that the hydride transfer is the main pathway in the 1-propanol/ozone system can probably be transferred on other systems in which the substrate is characterized by C&minus, H active sites only.

This study focuses on a formulation within the theory of porus media for continuum multicomponent modeling of bacterial driven methane oxidation in a porous landfill cover layer which consists of a porous solid matrix (soil and bacteria) saturated by a liquid (water) and gas phase. The solid, liquid, and gas phases are considered as immiscible constituents occupying spatially their individual volume fraction. However, the gas phase is composed of three components, namely methane (CH4), oxygen (O2), and carbon dioxide (CO2). A thermodynamically consistent constitutive framework is derived by evaluating the entropy inequality on the basis of Coleman and Noll [8], which results in constitutive relations for the constituent stress and pressure states, interaction forces, and mass exchanges. For the final set of process variables of the derived finite element calculation concept we consider the displacement of the solid matrix, the partial hydrostatic gas pressure and osmotic concentration pressures. For simplicity, we assume a constant water pressure and isothermal conditions. The theoretical formulations are implemented in the finite element code FEAP by Taylor [29]. A new set of experimental batch tests has been created that considers the model parameter dependencies on the process variables; these tests are used to evaluate the nonlinear model parameter set. After presenting the framework developed for the finite element calculation concept, including the representation of the governing weak formulations, we examine representative numerical examples.

Agrochemical products are a mixture of active ingredient(s) and inerts, which serve as dispersing or wetting agent or as emulsifiers. Varying qualities of these raw materials can have a significant impact on the properties of the final agrochemical product and so its quality has to be controlled. In this work the commercially available mixture of sodium bis(2-ethylhexyl) sulfosuccinate (trade name: Aerosol OT or AOT) and its surface active isomeric by-products sodium 1-carboxy-3-[(2-ethylhexyl)oxy]-3-oxopropane-1-sulfonate and sodium 3-carboxy-1-[(2-ethylhexyl)oxy]-1-oxopropane-2-sulfonate were analyzed. A method using liquid chromatography coupled with time-of-flight mass spectrometry (LC-ToF–MS) with exact mass measurement was developed to quantify these molecules simultaneously. Both by-products were not commercially available and thus were synthesised as analytical standards for method validation. For this purpose, two regio-selective syntheses were developed. Validation was done according to DIN 32645 and recovery and precision for two different matrices were determined. Significant differences were observed in the by-product spectrum of real samples of Aerosol OT of three different suppliers. Their influence on the properties of an agrochemical can now be investigated, as a precise and accurate determination of the target analytes has been developed in this work.

Gadolinium chelates are used in increasing amounts as contrast agents in magnetic resonance imaging, and their fate in wastewater treatment has recently become the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd-DTPA, Gd-DTPA-BMA, and Gd-BT-DO3A, which were found to be 4.8 ± 0.88, 46 ± 2.5, and 24 ± 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of (•)OH. Different methods have been applied and compared for determination of k((•)OH+Gd chelate). From rate constants determined by pulse radiolysis experiments (k((•)OH+Gd-DTPA) = 2.6 ± 0.2 × 10(9) M(-1) s(-1), k((•)OH+Gd-DTPA-BMA) = 1.9 ± 0.7 × 10(9) M(-1) s(-1), k((•)OH+Gd-BT-DO3A) = 4.3 ± 0.2 × 10(9) M(-1) s(-1)), it is concluded that a reaction in wastewater via (•)OH radicals is feasible. Toxicity has been tested for educt and product mixtures of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable.

Multi-walled carbon nanotubes were evaluated as sorptive packing material for in-tube microextraction (ITEX2) in combination with GC-MS for the analysis of benzene, toluene, ethylbenzene, xylenes, and naphthalene in aqueous samples. For method development, a three-level full factorial design of experiment (DoE) was performed incorporating extraction temperature, number of extraction strokes, and extraction flow. The statistical analysis of method development showed that all considered extraction parameters significantly affected the extraction yield. Furthermore, it was shown that some factors significantly interacted with each other, which indicates the advantage of using DoE for method development. The thereby optimized ITEX2 protocol was validated regarding its linear dynamic range, method detection limit (MDL), and precision. The MDLs of investigated analytes ranged between 2 ng L(-1) for naphthalene and 11 ng L(-1) for p-xylene. The relatively low MDL obtained for naphthalene, despite its comparably low air-water partitioning, can be explained by its strong interaction with carbon nanotubes. All obtained MDLs are at least comparable to previous reports on microextraction techniques, emphasizing both the quality of ITEX2 and the highly promising sorbent characteristics of carbon nanotubes. Furthermore, the method was applied to three real samples, which demonstrated good recoveries of analytes from tap water, a bank filtrate, and an effluent from a wastewater treatment plant.

A reliable quantification by LC-ESI-MS/MS as the most suitable analytical method for polar substances in the aquatic environment is usually hampered by matrix effects from co-eluting compounds, which are unavoidably present in environmental samples. The standard addition method (SAM) is the most appropriate method to compensate matrix effects. However, when performed manually, this method is too labour- and time-intensive for routine analysis. In the present work, a fully automated SAM using a multi-purpose sample manager “Open Architecture UPLC®-MS/MS” (ultra-performance liquid chromatography tandem mass spectrometry) was developed for the sensitive and reliable determination of 29 polar pesticide metabolites in environmental samples. A four-point SAM was conducted parallel to direct-injection UPLC-ESI-MS/MS determination that was followed by a work flow to calculate the analyte concentrations including monitoring of required quality criteria. Several parameters regarding the SAM, chromatography and mass spectrometry conditions were optimised in order to obtain a fast as well as reliable analytical method. The matrix effects were examined by comparison of the SAM with an external calibration method. The accuracy of the SAM was investigated by recovery tests in samples of different catchment areas. The method detection limit was estimated to be between 1 and 10 ng/L for all metabolites by direct injection of a 10-μL sample. The relative standard deviation values were between 2 and 10 % at the end of calibration range (30 ng/L). About 200 samples from different water bodies were examined with this method in the Rhine and Ruhr region of North Rhine-Westphalia (Germany). Approximately 94 % of the analysed samples contained measurable amounts of metabolites. For most metabolites, low concentrations ≤0.10 μg/L were determined. Only for three metabolites were the concentrations in ground water significantly higher (up to 20 μg/L). In none of the examined drinking water samples were the health-related indication values (between 1 and 3 μg/L) for non-relevant metabolites exceeded.

The sulfonamide antibiotic sulfamethoxazole (SMX) is a widely detected micropollutant in surface and groundwaters. Oxidative treatment with e.g. ozone or chlorine dioxide is regularly applied for disinfection purposes at the same time exhibiting a high potential for removal of micropollutants. Especially for nitrogen containing compounds such as SMX, the related reaction mechanisms are largely unknown. In this study, we systematically investigated reaction stoichiometry, product formation and reaction mechanisms in reactions of SMX with ozone and chlorine dioxide. To this end, the neutral and anionic SMX species, which may occur at typical pH-values of water treatment were studied. Two moles of chlorine dioxide and approximately three moles of ozone were consumed per mole SMX degraded. Oxidation of SMX with ozone and chlorine dioxide leads in both cases to six major transformation products (TPs) as revealed by high-resolution mass spectrometry (HRMS). Tentatively formulated TP structures from other studies could partly be confirmed by compound-specific stable isotope analysis (CSIA). However, for one TP, a hydroxylated SMX, it was not possible by HRMS alone to identify whether hydroxylation occurred at the aromatic ring, as suggested in literature before, or at the anilinic nitrogen. By means of CSIA and an analytical standard it was possible to identify sulfamethoxazole hydroxylamine unequivocally as one of the TPs of the reaction of SMX with ozone as well as with chlorine dioxide. H-abstraction and electron transfer at the anilinic nitrogen are suggested as likely initial reactions of ozone and chlorine dioxide, respectively, leading to its formation. Oxidation of anionic SMX with ozone did not show any significant isotopic fractionation whereas the other reactions studied resulted in a significant carbon isotope fractionation.

Carbon-based nanomaterials (CNM) represent promising materials for the application as sorbents in micro- and other extraction devices. In this work, we investigate the applicability of five different CNM (multi-walled carbon nanotubes (MWCNTs), fullerenes, carboxylic acid functionalized multi-walled carbon nanotubes (MWCNTs-COOH), graphene platelets, and carbon nanohorns) for their performance on PAH extraction from the aqueous phase by headspace in-tube extraction (HS-ITEX). Optimal extraction parameters for HS-ITEX were determined using a Box-Behnken experimental design. From the extraction yield response, central point analysis, fullerenes showed the best extraction properties for the eight selected headspace compatible PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene). Fullerenes were used for a further method validation including the linear range, limit of detection, precision, as well as recovery. Finally, extraction yields were compared to a commercial material (Tenax GR), demonstrating that fullerene represents a better option as sorbent in ITEX for PAH analysis. Method detection limits for the PAH on fullerene ranged from 10 to 300 ng L−1, with recoveries between 45 and 103%.

The performance of micro-liquid chromatography columns with an inner diameter of 0.3mm was investigated on a dedicated micro-LC system for gradient elution. Core-shell as well as fully porous particle packed columns were compared on the basis of peak capacity and gradient kinetic plot limits. The results for peak capacity showed the superior performance of columns packed with sub-2μm fully porous particles compared to 3.0μm fully porous and 2.7μm core-shell particles within a range of different gradient time to column void time ratios. For ultra-fast chromatography a maximum peak capacity of 16 can be obtained using a 30s gradient for the sub-2μm fully porous particle packed column. A maximum peak capacity of 121 can be achieved using a 5min gradient. In addition, the influence of an alternative detector cell on the basis of optical waveguide technology and contributing less to system variance was investigated showing an increased peak capacity for all applied gradient time/column void time ratios. Finally, the influence of pressure was evaluated indicating increased peak capacity for maximum performance whereas a limited benefit for ultra-fast chromatography with gradient times below 30s was observed.

Effluents from municipal wastewater treatment plants (WWTPs) are known to be point sources of micropollutants for surface waters. The aim of this study was to examine a reconstructed full-scale ozonation equipped with a pump-injector system for ozone (O3) dosage and a fluidized moving-bed reactor as biological posttreatment at a municipal WWTP utilizing an effect-directed approach. This approach consists of chemical analysis in combination with toxicological tests for the assessment of treatment efficiency of the plant. Chemical analysis showed elimination rates > 80% for pharmaceuticals and industrial chemicals. Analysis of endocrine disruptors was limited due to substance concentrations below the limit of detection (LOD). Estrogenic activity was detected by the Arxula Adeninivorans yeast estrogen screen (A-YES) at low concentrations (pg to ng EEQ/l range). Estrogenic activity was reduced by more than 90% after ozonation. In contrast, androgenic activity (measured in the Adeninivorans yeast androgen screen, A-YAS) was still found after O3 treatment and after biological posttreatment, which is consistent with the data obtained by chemical analysis. Furthermore, no marked genotoxic or cytotoxic effects were observed after ozonation using the alkaline comet and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT) assays, respectively. Results suggest that the applied specific O3 dose of 0.4 mgO3/mgDOC is a safe operation setup in terms of toxicologically relevant transformation products. In addition, no adverse effects on primary producers, as evidenced by algae growth inhibition tests, were detected. The monitored biofilm growth in the biological posttreatment exhibited a steady state after one month. Based on computational fluid dynamics (CFD) simulations and biomass, one might conclude that O3 did not apparently enter biological posttreatment to a great extent and that hydraulic retention time in the O3 reactor was sufficient. Our data demonstrate the effectiveness of a full-scale O3 treatment in combination with a fluidized moving-bed reactor as biological posttreatment for the reduction of a majority of micropollutants without the release of relevant toxic transformation products as assessed by a chemical and toxicity-based approach.

The determination of mineral oil aromatic hydrocarbons (MOAH) in foodstuffs gained in importance over the last years as carcinogenicity cannot be excluded for certain MOAH. The existence of olefins in foodstuffs, such as edible oils and fats, can be problematic for the determination of MOAH by LC-GC-FID. Removal of these interfering substances by HPLC based on polarity differences is not possible. During gas chromatographic separation heavily overloaded peaks are observed rendering the detection of small mineral oil contaminations almost impossible. Therefore, removal of these olefins is necessary before subjection of the sample to LC-GC-FID. Epoxidation of olefins to increase their polarity proved to be a valuable tool in the past. Precision and trueness of the results as shown in a collaborative trial, however, are relying on exact reaction conditions. Additionally, it is known that certain MOAH are oxidized during epoxidation and therefore get lost. In the scope of this work, hydroboration, bromohydrin reaction, and epoxidation were examined for their potential for derivatization of unsaturated hydrocarbons with increased robustness and higher recovery of MOAH. Epoxidation by meta-chloroperoxybenzoic acid (mCPBA) delivered the best removal of olefins. Factors influencing this reaction were enlightened. Adaption of the reaction conditions and time-controlled automation increased the recovery of polycyclic MOAH. Good precision (RSDr

Nebivolol (NEB) is one of the top-sold prescription drugs belonging to the third generation of beta-blockers. However, so far, occurrence data in the environment are lacking. Within this study NEB has been found for the first time in effluent samples of wastewater treatment plants in Germany with an average concentration of 13 ng L −1 . Its photodegradation behavior in the environment and in technical processes is largely unknown. To fill this gap, three different UV treatment procedures (UV-C at 254 nm, UV-B at 312 nm and UV-A at 365 nm) were investigated in three different matrices: pure water, pure water in presence of the hydroxyl radical ( OH) scavenger tert. -butanol and real wastewater. No elimination was observed during UV-A treatment. In contrast, NEB degradation during UV-B and UV-C treatment followed pseudo first order reaction kinetics, with highest removal rate during UV-C treatment in pure water (k = 7.8 × 10 −4 s −1 ). The rate constant for UV-C irradiation decreased to 2.9 × 10 −4 s −1 in the presence of the OH scavenger and in the presence of the wastewater matrix. The rate constant for the UV-B lamp was 4.4 × 10 −4 s −1 , Three transformation products were identified after UV-B and UV-C photolytic degradation using high resolution mass spectrometry. The main photoreaction is the substitution of the fluorine atoms of NEB by hydroxyl groups. A photolytic cleavage of the C F bond can be excluded as the high bond dissociation energy of aromatic C F bonds (525 kJ mol −1 ), exceeds the energy of electromagnetic radiation applied in the present study (≥254 nm, i.e., max. 471 kJ E −1 ). The quantum yields for NEB degradation for the UV-C lamp achieved in pure water, the OH scavenged system and wastewater matrix were Φ deg = 0.53, 0.19 and 0.22, respectively. For UV-B Φ deg was 0.023 ± 0.003, noticeable differences in quantum yield were not found. The photooxidation involves reactive oxygen species such as superoxide and singlet oxygen. These oxidative species may be formed upon reaction of photo-excited NEB with oxygen.

Surface properties, dispersion state, and sorption behavior of carbon-based nanomaterials will change after being released into the environment. To study these processes, five different scenarios were considered to probe the impact of changes in surface properties of dispersed fullerenes (nC60) on their sorption potential due to irradiation and presence of oxygen. Sorption isotherms of pyrene by nC60 were determined at environmentally relevant concentrations applying a passive sampling method. Isotherms of all dispersion scenarios were best fit with the Dubinin-Ashthakov model. Sorption was strongest for nC60 kept under anoxic condition. Both the presence of oxygen and irradiation significantly decreased the sorption capacity of nC60, while commercially available polyhydroxy fullerenes had the smallest sorption. In addition, competition for sorption sites was never observed in multiple sorbate experiments with four polycyclic aromatic hydrocarbons at small concentration. A strong relationship between sorption coefficients and hydrophobic properties of sorbates suggests that hydrophobic interactions are of major importance. The results emphasize that aging of released fullerenes results in a reduced strength of interactions with nonpolar compounds and, thus, reduces the impact on the environmental transport of hydrophobic pollutants.

The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro-liquid chromatography system. Fully porous, core-shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub-2 μm fully porous as well as the 2.7 μm core-shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56-2.69) before correction for extra-column contribution compared to normal-bore columns. Moreover, the influence of extra-column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub-2 μm fully porous particle packed column for ultra-fast liquid chromatography.

Cefapirin (CEPA) and ceftiofur (CEF) are two examples of widely used veterinarian cephalosporins presenting multiple ionization centers. However, the acid dissociation constants (pK

A fast quantification method for the determination of 11 antineoplastic drugs from wipe samples was developed using micro-scale liquid chromatography in combination with tandem mass spectrometry. The extraction efficiency from the wipes has been investigated using different extraction solvents. The results indicate that a mixture of 70/30 water/isopropanol (v/v) acidified with 0.1 % formic acid is suitable to desorb the antineoplastic drugs with sufficient recovery between 80 and 120 %. Compared to conventional liquid chromatography, the total analysis time can be reduced to 2.25 min using a 50 × 0.3 mm column at a flow rate of 25 μL min−1. Ion source parameters as well as the injection volume were optimized to ensure the highest sensitivity. The results of method validation showed an instrumental limit of quantification between 0.0068 and 0.0488 ng mL−1 using an injection volume of 4.25 μL estimated by the signal to noise ratio. Moreover, the retention time repeatability was determined with a maximum relative standard deviation of 0.4 %.

For the identification of the optimal column combinations, a comparative orthogonality study of single columns and columns coupled in series for the first dimension of a microscale two-dimensional liquid chromatographic approach was performed. In total, eight columns or column combinations were chosen. For the assessment of the optimal column combination, the orthogonality value as well as the peak distributions across the first and second dimension was used. In total, three different methods of orthogonality calculation, namely the Convex Hull, Bin Counting, and Asterisk methods, were compared. Unfortunately, the first two methods do not provide any information of peak distribution. The third method provides this important information, but is not optimal when only a limited number of components are used for method development. Therefore, a new concept for peak distribution assessment across the separation space of two-dimensional chromatographic systems and clustering detection was developed. It could be shown that the Bin Counting method in combination with additionally calculated histograms for the respective dimensions is well suited for the evaluation of orthogonality and peak clustering. The newly developed method could be used generally in the assessment of 2D separations. Graphical Abstract ᅟ.

Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample.

Author(s): Fechner, Uli; de Graaf, Chris; Torda, Andrew E; Gussregen, Stefan; Evers, Andreas; Matter, Hans; Hessler, Gerhard; Richmond, Nicola J; Schmidtke, Peter; Segler, Marwin HS; Waller, Mark P; Pleik, Stefanie; Shea, Joan-Emma; Levine, Zachary; Mullen, Ryan; van den Broek, Karina; Epple, Matthias; Kuhn, Hubert; Truszkowski, Andreas; Zielesny, Achim; Fraaije, Johannes Hans; Gracia, Ruben Serral; Kast, Stefan M; Bulusu, Krishna C; Bender, Andreas; Yosipof, Abraham; Nahum, Oren; Senderowitz, Hanoch; Krotzky, Timo; Schulz, Robert; Wolber, Gerhard; Bietz, Stefan; Rarey, Matthias; Zimmermann, Markus O; Lange, Andreas; Ruff, Manuel; Heidrich, Johannes; Onlia, Ionut; Exner, Thomas E; Boeckler, Frank M; Bermudez, Marcel; Firaha, Dzmitry S; Holloczki, Oldamur; Kirchner, Barbara; Tautermann, Christofer S; Volkamer, Andrea; Eid, Sameh; Turk, Samo; Rippmann, Friedrich; Fulle, Simone; Saleh, Noureldin; Saladino, Giorgio; Gervasio, Francesco L; Haensele, Elke; Banting, Lee; Whitley, David C; Oliveira Santos, Jana Sopkova-de; Bureau, Ronan; Clark, Timothy; Sandmann, Achim; Lanig, Harald; Kibies, Patrick; Heil, Jochen; Hoffgaard, Franziska; Frach, Roland; Engel, Julian; Smith, Steven; Basu, Debjit; Rauh, Daniel; Kohlbacher, Oliver; Boeckler, Frank M; Essex, Jonathan W; Bodnarchuk, Michael S; Ross, Gregory A; Finkelmann, Arndt R; Goller, Andreas H; Schneider, Gisbert; Husch, Tamara; Schutter, Christoph; Balducci, Andrea; Korth, Martin; Ntie-Kang, Fidele; Gunther, Stefan; Sippl, Wolfgang; Mbaze, Luc Meva'a

The article contains sections titled: 1. Properties of Pure Water 1.1. Molecular Properties 1.1.1. Isotopic Composition 1.1.2. The Water Molecule 1.1.3. Hydrogen Bonding and Water Structure 1.2. The Phase Behavior of Water 1.2.1. Invariant Points 1.2.2. Liquid-Vapor Equilibria 1.2.3. Solid-Liquid and Solid-Solid Equilibria 1.2.4. Supercooled Water and Amorphous Ice 1.3. Properties of Liquid and Supercritical Water 1.3.1. Water over Wide Ranges in Temperature and Pressure 1.3.2. Equation of State and Volumetric Properties 1.3.3. Thermodynamic Properties 1.3.4. Transport Properties 1.3.5. Surface Tension 1.3.6. Auto-protolysis 1.3.7. Dielectric Properties 2.2.2. Transport Properties 2. Water as a Solvent 2.1. Solvent Properties of Water 2.2. Solutions of Nonpolar Gases and Hydrophobic Species 2.3. Hydrophilic Solutes 2.4. Electrolyte Solutions 2.5. Supercritical Water as a Solvent 3. Water Analysis 3.1. Sampling and Sample Preservation 3.2. Physicochemical and Sum Parameters 3.3. Inorganic Analysis 3.3.1. Determination of Cations 3.3.2. Anion Analysis 3.3.3. Determination of Dissolved Gases 3.3.4. Rapid Tests 3.4. Organic Analysis 3.4.1. Spectrometric Methods 3.4.2. Gas and Liquid Chromatography 3.5. Bioanalytical Methods 4. Hydrological Cycle and Water Use 4.1. World Water Balance 4.2. Hydrological Cycle 4.3. Demand for Water 4.4. Source of Water Used 4.5. Water Treatment

High-temperature liquid chromatography provides several advantages concerning HPLC method development and is needed to realize special hyphenation techniques. However, hardware limitations and stationary phase degradation can prevent the successful application of this technique. Therefore, column stability is of major importance. The presented study contains results of long-term high-temperature stability tests for eight modern commercially available HPLC stationary phases. Six of them were silica-based reversed-phase C18 columns tested according to an earlier reported procedure (Teutenberg, 2009 [12]). On the basis of the extended data set that covers a wide range of column technologies, a comparative approach using retention factor analysis was evaluated in order to categorize the columns according to their long-term high-temperature stability at 150 °C and changing pH value. This approach offers a more objective alternative to conventional listings in which temperature maxima are compared for columns tested under different conditions. Additionally, customized tests are presented for one promising polymer-based C18 stationary phase and an amide column for hydrophilic interaction liquid chromatography.

Within the past 15 years, compound-specific stable isotope analysis has continued to increase in popularity in the area of contaminant hydrology of organic molecules. In particular, in cases where concentration data alone are insufficient to elucidate environmental processes unequivocally, the isotope signature can provide additional unique information. Specifically, it can help answer questions about contaminant source apportionment, quantification of biotic and abiotic processes, and identification of transformation reactions on a mechanistic level. We review advances in laboratory and field investigations and exemplary applications in contaminant hydrology via stable isotope analysis. We also highlight future directions in the field.

RATIONALE Plastics are increasingly used as packaging materials for pharmaceuticals. However, diffusion of compounds in plastic into drugs may endanger patients' health. Regulatory authorities therefore demand detailed information about leachable compounds in plastics. Here we identify migrating components of a sterilization-resistant polyurethane (PUR) adhesive used in the primary packaging for an aqueous pharmaceutical. This identification is an essential first step for quantification and toxicological evaluation of the compounds. METHODS We used various hyphenated mass spectrometry (MS) methods: gas chromatography (GC/MS) with either electron impact ionization or chemical ionization, and high resolution liquid chromatography (LC/MS) with electrospray ionization. RESULTS Of the 13 migrating substances detected, 11 are cyclic esters with characteristic fragmentation schemes apparent from their mass spectra. These esters are formed as by-products during the reaction of adipic and isophthalic acid with monoethylene glycol and diethyelene glycol. A cyclic ester of isophthalic acid and tetraethylene glycol and a product of the reaction of isophoron diisocyanate with methanol were clearly identified. CONCLUSIONS Complementary use of several hyphenated mass spectrometric methods enables successful identification of leachable compounds in the PUR adhesive under study. This opens the way for quantification and evaluation of the potential toxicities of these compounds. Despite the range of compositions of PUR laminates, the approach presented here may be applicable for the qualitative assessment of all PURs. Copyright © 2012 John Wiley & Sons, Ltd.

Solvent compatibility is a limiting factor for the success of two-dimensional liquid chromatography (2-D LC). In the second dimension, solvent effects can result in overpressures as well as in peak broadening or even distortion. A peak shape study was performed on a one-dimensional high-performance liquid chromatography (HPLC) system to simulate the impact of peak distorting solvent effects on a reversed-phase second dimension separation operated at high temperatures. This study includes changes in injection volume, solute concentration, column inner diameter, eluent composition and oven temperature. Special attention was given to the influence of high temperatures on the solvent effects. High-temperature HPLC (HT-HPLC) is known to enhance second dimension separations in terms of speed, selectivity and solvent compatibility. The ability to minimise the viscosity contrast between the mobile phases of both dimensions makes HT-HPLC a promising tool to avoid viscosity mismatch effects like (pre-)viscous fingering. In case of our study, viscosity mismatch effects could not be observed. However, our results clearly show that the enhancement in solvent compatibility provided by the application of high temperatures does not include the elimination of solvent strength effects. The additional peak broadening and distortion caused by this effect is a potential error source for data processing in 2-D LC.