Chemistry of organic traces in air,XI: Sources and variations of volatile halocarbons in rural and urban air in Southern Germany

The variations of concentrations of volatile halocarbons (CHCl₃, CCl₄, CH₂Cl—CH₂Cl, CCl₃—CH₃, CHCl—CCl₂, and CCl₂=CCl₂) in rural and urban air are demonstrated by two series of air sampling carried out in Southern Germany. The interpretation of the changes in concentrations for the individual compounds is based on specific local input for the chlorinated solvents and on changing weather conditions during the sampling periods.Dedicated to Professor J. F. K. Huber on the occasion of his 65th birthday     

Sol–gel‐adsorbent‐coated extraction needles to detect volatile compounds in spoiled fish

Volatile compounds generated by fish spoilage were investigated by an inside‐needle microextraction method followed by gas chromatography with flame ionization detection and gas chromatography with mass spectrometry. The inside of a needle was coated with an adsorbent to extract the target analytes from the headspace of the sample. The examined adsorbents included β‐cyclodextrin, polystyrene resin cross‐linked with 1% divinylbenzene, and polyethylene glycol mixed with polydimethylsiloxane. The investigated volatile compounds generated by fish spoilage were acetone, 2‐butanone, 2‐butanol, 2‐propanol, dimethyl disulfide, acetic acid, and benzaldehyde. The analysis conditions for the sorption and desorption processes were optimized. Each optimized condition was validated by determining the limit of detection and the limit of quantitation from the calibration curves, as well as the recovery, reproducibility, and concentration factors. As a result, all of the fabricated needles afforded successful recoveries, above 90%, with relative standard deviations below 10%. In particular, cyclodextrin and polystyrene resin cross‐linked with 1% divinylbenzene mixed with polydimethylsiloxane show good sensitivities and concentration factors for the standard volatile compounds. The storage of fresh mackerel and salted mackerel at room temperature for 14 days caused the concentrations of dimethyl disulfide and acetic acid to significantly increase while those of acetone, 2‐butanone, 2‐propanol, and 2‐butanol changed only slightly.     

Evaluation of needle trap micro‐extraction and solid‐phase micro‐extraction: Obtaining comprehensive information on volatile emissions from in vitro cultures

Volatile organic compounds (VOCs) emitted from in vitro cultures may reveal information on species and metabolism. Owing to low nmol L⁻¹ concentration ranges, pre‐concentration techniques are required for gas chromatography–mass spectrometry (GC–MS) based analyses. This study was intended to compare the efficiency of established micro‐extraction techniques – solid‐phase micro‐extraction (SPME) and needle‐trap micro‐extraction (NTME) – for the analysis of complex VOC patterns. For SPME, a 75 μm Carboxen®/polydimethylsiloxane fiber was used. The NTME needle was packed with divinylbenzene, Carbopack X and Carboxen 1000. The headspace was sampled bi‐directionally. Seventy‐two VOCs were calibrated by reference standard mixtures in the range of 0.041–62.24 nmol L⁻¹ by means of GC–MS. Both pre‐concentration methods were applied to profile VOCs from cultures of Mycobacterium avium ssp. paratuberculosis. Limits of detection ranged from 0.004 to 3.93 nmol L⁻¹ (median = 0.030 nmol L⁻¹) for NTME and from 0.001 to 5.684 nmol L⁻¹ (median = 0.043 nmol L⁻¹) for SPME. NTME showed advantages in assessing polar compounds such as alcohols. SPME showed advantages in reproducibility but disadvantages in sensitivity for N‐containing compounds. Micro‐extraction techniques such as SPME and NTME are well suited for trace VOC profiling over cultures if the limitations of each technique is taken into account.     

Application of chemometric methods to the investigation of main microcontaminant sources of endocrine disruptors in coastal and harbour waters and sediments

Identification, resolution and distribution of main microcontaminant sources of endocrine disruptors in Spanish harbours, coastal waters and sediments are investigated using chemometric methods. We investigated eighteen different endocrine disruptor chemical compounds, including non-ionic surfactants, their degradation products and linear alkylbenzene sulfonates, found in a total number of 74 samples (35 water samples and 39 sediment samples) over a period of 16 months from March 1999 to July 2000, and in 32 different geographical sites along the Spanish Mediterranean Coast (e.g. Barcelona, Tarragona, Almeria Harbour, Malaga and the Bay of Cadiz). Main environmental contamination sources of these endocrine disruptor compounds were investigated and interpreted according to their chemical composition and according to their resolved geographical distribution profiles.An erratum to this article can be found at     

Measurements of arsenite and arsenate contained in mining river waters and leached from contaminated sediments by sequential hydride generation flow injection analysis

In this work, a new analytical method for gasifiable compounds based on sequential hydride generation flow injection analysis (SHGFIA) was applied to water analysis and leaching investigation. For water analysis, it was confirmed that 1 μg L⁻¹ As(III) and As(V) were stable for a few days when EDTA was added in the sample waters. Dissolved As(III) and total arsenic (As(III) + As(V)) were converted to AsH₃ in neutral and acidic medium, respectively, to transfer to a miniature gas scrubber (100 μL in absorber volume). The collected arsenic was successively measured by flow analysis based on molybdenum blue chemistry. With this system, changes in As(III) and As(V) concentrations of water placed with arsenic-contaminated-sediment was monitored in near real time. From these data, kinetic analyses were carried out and kinetic constant was obtained from plot of ln{(C^∞ − C)/C^∞} where C and C^∞ were leached arsenic concentration and its final concentration, respectively. It was found that rate of As(III) leaching was much faster than that of As(V) while As(V) leached more in amount compared to As(III). In this work, it was demonstrated that kinetic investigation is also one of the important application of flow analysis. The SHGFIA system showed excellent performance for leaching analysis of arsenic with discrimination of As(III) and As(V).     

Tri‐n‐butyltin binding to a low‐affinity site decreases the F1FO‐ATPase sensitivity to oligomycin in mussel mitochondria

In mussel digestive gland mitochondria the environmental pollutant tri‐n‐butyltin (TBT), other than strongly inhibiting ATPase activity at <1.0 μ m , at ≥1.0 μ m concentration was previously found to desensitize F₁F_O‐ATPase to the antibiotic oligomycin. While F₁F_O‐ATPase inhibition is widely known as one of the main mitochondrial damages caused by TBT, the enzyme's desensitization to oligomycin was quite unexpected. The possible mechanisms involved are here stepwise approached, aiming at enlightening the molecular mechanism(s) of TBT toxicity and the still poorly investigated oligomycin interaction with F_O. The findings strongly suggest that the oligomycin desensitization directly stems from the covalent binding of TBT to monothiols of the F₁F_O‐ATPase. This binding implies sulfur oxidation, irrespective of the possible formation of radical species in mitochondria, a mechanism which does not seem to be involved here. It is hypothesized that TBT interacts with the enzyme complex in at least two sites distinguished by different affinities: TBT binding to the high‐affinity site would lead to ATPase inhibition, while TBT binding to monothiols in the low‐affinity site could mirror the decrease in F₁F_O‐ATPase oligomycin sensitivity at ≥1.0 μ m TBT. Experiments carried out on inside‐out submitochondrial particles hint that TBT binding destabilizes the oligomycin‐blocked F_O conformation, allowing proton flux recovery within F_O, without uncoupling the catalytic function from proton channeling. Copyright © 2012 John Wiley & Sons, Ltd.     

Evalution of sequential extractions on dry and wet sediments

A five-step sequential extraction procedure was applied on dried and wet Ballastplaat Scheldt estuary sediments. When wet (fresh) sediments were used, all sample handling up to the 3rd extraction step, inclusive, was carried out under inert atmosphere. The repeatability of the procedure was very good on dry samples. For Fe as for Mn, RSD values are lower than 4%, except for Mn in the fifth extraction step where a spread of 10% is observed. The observed RSDs for Pb are of the same order of magnitude as those for Mn. On wet samples the spread of the results is higher than on dried ones. The highest RSDs observed for Fe amount to 20%, for Mn to 15% but for Pb an RSD of up to 44% was found. Better homogenization of the solid sediment part of lyophilized sediments and different porosities of wet sediment sub-samples may be the explanation. These results also indicated that drying/oxidizing of the sediment sample causes a shift from less available/mobile metal fractions to more available/mobile fractions. The Mn and Fe oxyhydroxide spikes added to a wet sediment sample were recovered between 100±10%. The results obtained after changing the sequence of the extraction steps (multiple rotations and inversions were tested) corroborated the progressive increase in the aggressive nature of the extraction solutions in our standard scheme. Although there is also no need to change the ratio volume of extractant to amount of sediment, increasing the number of extraction repetitions in steps 1 to 3 resulted, for some of those extraction steps, in a partially modified analyte distribution. Finally the method was applied to sandy and muddy sediment cores of the Scheldt estuary and revealed clear differences between metal distributions in both types of sediment.     

Determination of volatile organic compounds in contaminated air using semipermeable membrane devices

Semipermeable membrane devices (SPMDs) were evaluated as passive samplers for the determination of 26 volatile organic compounds (VOCs) in contaminated air of occupational environments. A direct methodology based on the use of head-space-gas chromatography-mass spectrometry (HS-GC-MS) was developed for VOCs determinations in SPMDs, without any sample pre-treatment and avoiding the use of solvents. A desorption temperature of 150 °C for 10 min was sufficient for a sensitive VOCs determination providing limits of detection in the range of 15 ng SPMD⁻¹ for 21 of 26 studied compounds. Linear and equilibrium uptake models were established for each VOC from compound isotherms. Highly volatile compounds were slightly absorbed and moderately volatile compounds were strongly absorbed by SPMDs. This study is the first precedent of the use of SPMDs for the simultaneous sampling of a wide number of VOCs. The use of SPMDs is a simple and low cost alternative to ordinary sampling devices such as Radiello^® diffusive samplers or badge-type solid-phase supports.     

Analytical methods and problems related to the determination of organotin compounds in marine sediments

The determination of organotin compounds in bottom sediments is a complex process that requires a number of analytical steps, i.e. sample collection, transport and storage; extraction of analytes from sediment; derivatization; extract purification; enrichment; and the final chromatographic measurement. The whole process is time and labour consuming, and subject to securing sample representativeness. In this review the most frequently encountered problems and the examples of possible analytical solutions are presented, which encompass the specific steps of speciation analysis of these toxic compounds.     

Support vector machine classification of volatile organic compounds based on narrow‐band spectroscopic data

In this work, a list of volatile organic compounds (VOCs) that are associated with targets susceptible to versatile security issues – such as drug trafficking, explosives carrying, or human presence in forbidden areas – are monitored and discriminated through algorithmic processing of their midinfrared (MIR) spectroscopic properties. Usually, such tasks are relatively straightforward by identifying the absorption peaks of the investigated compounds in extended spectral recordings, from a few hundred up to many thousands of wavenumbers (cm⁻¹). Nevertheless, the physical mechanisms and instrumentation for obtaining so broad spectral profiles may prove to be complex, especially in field measurements, while data acquisition and processing may also prove to be time‐consuming. In the proposed approach, support vector machine algorithmic training is applied in order to evaluate the potential of exploiting very narrow spectral MIR absorption bands that are optimal for reliable prediction analysis and training. The probabilistic classification performance of these bands is evaluated and compared with the prediction performance when using wider MIR absorption spectra. Depending on the data set and the list of the associated VOCs, spectral data recording within a span up to several tens of wavenumbers – at regions where absorption is detectable – prove to be enough for efficient VOC classification. Copyright © 2014 John Wiley & Sons, Ltd.     

A 10‐year survey of trace metals in sediments using self‐organizing maps

Self‐organizing maps (SOMs) (in particular, Matrix reOrganization Layout to Map Analytical Patterns (MOLMAP)) were used to unravel the main patterns in a three‐way dataset after a preliminary unfolding of the cube. Eleven sites of the ría of Vigo (NW of Spain) were monitored during the last decade (from 2000 to 2010) to assess pollution trends in this area. Twelve trace metals (Hg, Pb, Cd, Cu, Zn, Cr, As, Li, Fe, Al, Ni and Mn), the total organic carbon and the percentage of fine particles were measured. Results from MOLMAP, the SOM‐based approach, were compared to those of three established alternatives: parallel factor analysis, matrix‐augmented principal component analysis and generalized Procrustes rotation, the latter two employing unfolding as well. MOLMAP showed the best capabilities to differentiate groups of samples. The spatial and temporal trends, as well as the analytical variables causing them, were almost the same for all methods, which confirms MOLMAP as a simple and reliable methodology to treat three‐way environmental datasets. Copyright © 2014 John Wiley & Sons, Ltd.     

Speciation Analysis of Butyltin Species in Water by Gas Chromatography with Flame Photometric Detection Using Quartz Surface-induced Tin Emission

A flame photometric detector using quartz surface-induced tin emission was designed and evaluated for quantification analysis of butyltin species. It has been demonstrated that this quartz surface-induced tin emission, centred at 390 nm, is more sensitive than the commonly used gas-phase emission at 610 nm. The dependence of detector response on quartz enclosure was studied. The operational variables such as hydrogen–air flow rate, carrier-gas flow rate and purge-gas flow rate were optimized. An analytical procedure for speciation analysis of butyltin species in water using simultaneous hydride generation with sodium borohydride and extraction into dichloromethane was established. The detection limits (defined as the signals that equal three times the deviations of the noise) were 0.3 pg of Sn for tetrabutyltin (TeBT), 5 pg of Sn for monobutyltin (MBT), 18 pg of Sn for dibutyltin (DBT) and 2 pg of Sn for tributyltin (TBT), which are approximately 10- to 30-fold better than those reported for using more commonly used gas-phase emission centred at 610 nm.     

Ultrasound‐assisted extraction method for the simultaneous determination of emerging contaminants in freshwater sediments

Sediments are the fate of several emerging organic contaminants, such as pharmaceuticals, personal care products and hormones, and therefore an important subject in environmental monitoring studies. In the present work, a simple and sensitive method was developed, validated and applied for the simultaneous extraction of atenolol, caffeine, carbamazepine, diclofenac, ibuprofen, naproxen, propranolol, triclosan, estrone, 17‐β‐estradiol and 17‐α‐ethinylestradiol using ultrasound‐assisted extraction from freshwater sediment samples followed by solid‐phase extraction clean‐up and liquid chromatography with tandem mass spectrometry detection. The solvent type and extraction pH were evaluated to obtain the highest recoveries of the compounds. The best method shows absolute recoveries between 54.0 and 94.4% at 50 ng/g concentration. The method exhibits good precision with relative standard deviation ranging from 1.0–16%. The detection and quantification limits ranged from 0.006–0.067 and 0.016–0.336 ng/g, respectively. The developed method was successfully applied to freshwater sediment samples collected from different sites in Jundiaí River basin of São Paulo State, Brazil. The compounds atenolol, caffeine, propranolol and triclosan were detected in all the sampling sites with concentrations of 13.8, 41.0, 28.5 and 176 ng/g, respectively.     

Analysis of volatile organic compounds in indoor environments using thermal desorption with comprehensive two‐dimensional gas chromatography and high‐resolution time‐of‐flight mass spectrometry

Building‐related health effects are frequently observed. Several factors have been listed as possible causes including temperature, humidity, light conditions, presence of particulate matter, and microorganisms or volatile organic compounds. To be able to link exposure to specific volatile organic compounds to building‐related health effects, powerful and comprehensive analytical methods are required. For this purpose, we developed an active air sampling method that utilizes dual‐bed tubes loaded with TENAX‐TA and Carboxen‐1000 adsorbents to sample two parallel air samples of 4 L each. For the comprehensive volatile organic compounds analysis, an automated thermal desorption comprehensive two‐dimensional gas chromatography high‐resolution time‐of‐flight mass spectrometry method was developed and used. It allowed targeted analysis of approximately 90 known volatile organic compounds with relative standard deviations below 25% for the vast majority of target volatile organic compounds. It also allowed semiquantification (no matching standards) of numerous nontarget air contaminants using the same data set. The nontarget analysis workflow included peak finding, background elimination, feature alignment, detection frequency filtering, and tentative identification. Application of the workflow to air samples from 68 indoor environments at a large hospital complex resulted in a comprehensive volatile organic compound characterization, including 178 single compounds and 13 hydrocarbon groups.     

Detection of volatile organic compounds in the headspace above mold fungi by GC‐soft X‐radiation–based APCI‐MS

Mold fungi on malting barley grains cause major economic loss in malting and brewery facilities. Possible proxies for their detection are volatile and semivolatile metabolites. Among those substances, characteristic marker compounds have to be identified for a confident detection of mold fungi in varying surroundings. The analytical determination is usually performed through passive sampling with solid phase microextraction, gas chromatographic separation, and detection by electron ionization mass spectrometry (EI‐MS), which often does not allow a confident determination due to the absence of molecular ions. An alternative is GC‐APCI‐MS, generally, allowing the determination of protonated molecular ions. Commercial atmospheric pressure chemical ionization (APCI) sources are based on corona discharges, which are often unspecific due to the occurrence of several side reactions and produce complex product ion spectra. To overcome this issue, an APCI source based on soft X‐radiation is used here. This source facilitates a more specific ionization by proton transfer reactions only. In the first part, the APCI source is characterized with representative volatile fungus metabolites. Depending on the proton affinity of the metabolites, the limits of detection are up to 2 orders of magnitude below those of EI‐MS. In the second part, the volatile metabolites of the mold fungus species Aspergillus, Alternaria, Fusarium, and Penicillium are investigated. In total, 86 compounds were found with GC‐EI/APCI‐MS. The metabolites identified belong to the substance classes of alcohols, aldehydes, ketones, carboxylic acids, esters, substituted aromatic compounds, terpenes, and sesquiterpenes. In addition to substances unspecific for the individual fungus species, characteristic patterns of metabolites, allowing their confident discrimination, were found for each of the 4 fungus species. Sixty‐seven of the 86 metabolites are detected by X‐ray–based APCI‐MS alone. The discrimination of the fungus species based on these metabolites alone was possible. Therefore, APCI‐MS in combination with collision induced dissociation alone could be used as a supervision method for the detection of mold fungi.     

Geographical discrimination of Chinese winter wheat using volatile compound analysis by HS‐SPME/GC‐MS coupled with multivariate statistical analysis

This study aimed to develop a potential analytical method to discriminate the Chinese winter wheat according to geographical origin and cultivars. A total of 90 wheat samples of 10 different wheat cultivars among three regions were examined by headspace solid phase microextraction coupled with gas chromatography‐mass spectrometry (GC‐MS). The peak areas of 32 main volatile compounds were selected and subjected to statistical analysis, which revealed significant differences among different regions and cultivars. Multivariate analysis of variance showed a significant influence of regions, wheat genotypes, and their interaction on the volatile composition of wheat. Principal component analysis of the aromatic profile showed better visualization for wheat geographical origins. Finally, a classification model based on the linear discriminant analysis was successfully constructed for the discrimination of regions and cultivars with the correct classification percentages of 90 and 100%, respectively.     

Determination of volatile organic compounds in urban and industrial air from Tarragona by thermal desorption and gas chromatography-mass spectrometry

This study describes the optimisation of an analytical method to determine 54 volatile organic compounds (VOCs) in air samples by active collection on multisorbent tubes, followed by thermal desorption and gas chromatography-mass spectrometry. Two multisorbent beds, Carbograph 1/Carboxen 1000 and Tenax/Carbograph 1TD, were tested. The latter gave better results, mainly in terms of the peaks that appeared in blank chromatograms. Temperatures, times and flow desorption were optimised. Recoveries were higher than 98.9%, except methylene dichloride, for which the recovery was 74.9%. The method's detection limits were between 0.01 and 1.25 μg m⁻³ for a volume sample of 1200 ml, and the repeatability on analysis of 100 ng of VOCs, expressed as relative standard deviation for n = 3, was lower than 4% for all compounds. Urban and industrial air samples from the Tarragona region were analysed. Benzene, toluene, ethylbenzene and xylenes (BTEX) were found to be the most abundant VOCs in urban air. Total VOCs in urban samples ranged between 18 and 307 μg m⁻³. Methylene chloride, 1,4-dichlorobenzene, chloroform and styrene were the most abundant VOCs in industrial samples, and total VOCs ranged between 19 and 85 μg m⁻³.     

Spontaneously Self‐Assembled Naphthalimide Nanosheets: Aggregation‐Induced Emission and Unveiling a‐PET for Sensitive Detection of Organic Volatile Contaminants in Water

A simple design strategy of long alkyl chain substitution was formulated to block the detrimental π–π interaction that potentially transforms the aggregation‐caused quenching (ACQ) chromophores into aggregation‐induced emission (AIE) active smart nanomaterials. The long octadecyl pendant chain substituted naphthalimide (NI) derivatives self‐assembled into fluorescent nanosheets (NS)‐like structures that spontaneously have surfaces coated with NI cores in water. The fluorescent NS were subsequently used to recognize the organic volatile contaminants (OVCs) at ppb levels via an acceptor‐excited photoinduced electron transfer (a‐PET) mechanism, unveiled as the first representative example. A new design strategy is thereby provided to detect toxic xylene derivatives in water using smart nanomaterials.     

Cairns港口海底沉积物中五种甾醇的分离

从澳大利亚Cairns港口海底沉积物中分离出五种甾醇化合物, 其中两种是具有植物生长调节活性的菜油甾醇和菜子甾醇。     

Qualitative screening for volatile organic compounds in human blood using solid‐phase microextraction and gas chromatography‐mass spectrometry

A fast and simple screening procedure using solid‐phase microextraction and gas chromatography‐mass spectrometry (SPME‐GC‐MS) in full‐scan mode for the determination of volatile organic compounds (VOC) is presented. The development of a fast and simple screening technique for the simultaneous determination of various volatiles is of great importance, because of their widespread use, frequent occurrence in forensic toxicological questions and the fact that there is often no hint on involved substances at the crime scene. To simulate a screening procedure, eight VOC with different chemical characteristics were chosen (isoflurane, halothane, hexane, chloroform, benzene, isooctane, toluene and xylene). To achieve maximum sensitivity, variables that influence the SPME process, such as type of fiber, extraction and desorption temperature and time, agitation and additives were optimized by preliminary studies and by means of a central composite design. The limits of detection and recoveries ranged from 2.9 µg/l (xylene) to 37.1 µg/l (isoflurane) and 7.9% (chloroform) to 61.5% (benzene), respectively. This procedure can be used to answer various forensic and toxicological questions. The short time taken for the whole analytical procedure may make its eventual adoption for routine analysis attractive. Copyright © 2010 John Wiley & Sons, Ltd.