Abstract: Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected stations were sampled for suspended sediments as well. The samples were analysed for a number of heavy metals (Fe, Mn, Ni, Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial variations in the heavy metals distributions. Suspended sediments are 510 times richer than the bed sediments. None of the tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the worldwide budget for heavy metal transport may need to be suitably revised.

Abstract: Continuous global urbanisation causes an ever-growing ecological footprint of pollution. Road dust (RD), one of these pollutants, poses a health concern due to carcinogenic and toxic components potentially present in the micron-sized fractions. The literature reports on the concentrations of trace, toxic metals and metalloids present in RD (Hooker and Nathanail in Chem Geol 226:340-351, 2006), but the literature on its molecular composition is limited. Recent reports on the bioaccessibility of platinum group metals are also reported (Colombo et al. in Chem Geol 226:340-351, 2008). In vitro and animal toxicological studies confirmed that the chemical composition of inhaled particles plays a major role in its toxic, genotoxic and carcinogenic mechanisms, but the component-specific toxic effects are still not understood. Particle-bound airborne transition metals can also lead to the production of reactive oxygen species in lung tissue; a special concern amongst particularly susceptible cohorts (children and elderly). The characterisation of the molecular composition of the fine fraction is evidently of importance for public health. During a pilot study, partially characterised size-fractioned RD samples (Barrett et al. in Eviron Sci Technol 44:2940-2946, 2010) were analysed for their elemental concentration using X-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. In addition, separately dispersed particles (200 particles per size fraction) were analysed individually by means of computer-controlled electron probe X-ray micro-analysis (CC-EPXMA) and their molecular structure probed by studying elemental associations. These were correlated with micro-Raman spectroscopy (MRS) results. It was found that the fine fraction (< 38 mu m) had the highest Pb (238 ppm) and Cr (171 ppm) concentrations. The CC-EPXMA data showed > 50 % association of Cr-rich particles with Pb, and the MRS data showed that the Cr was mostly present as lead chromate and therefore in the Cr(VI) oxidation state. Concentrations of both Pb and Cr decreased substantially (279 (< 38 mu m)-13 ppm (< 1 mm); 171 (< 38 mu m)-91 ppm (< 1 mm), respectively) in the larger fractions. Apart from rather alarmingly high concentrations of oxidative stressors (Cu, Fe, Mn), the carcinogenic and toxic potential of the inhalable fraction is evident. Preliminary bioaccessibility data indicated that both Cr and Pb are readily mobilised in artificial lysosomal liquid and up to 19 % of Cr and 47 % of Pb were released.

Abstract: Marine aerosols have extensively been monitored in the framework of a research project to investigate the inorganic and organic nutrient fluxes of the atmospheric nitrogen input into the North Sea. As a part of this project bulk analysis was also performed by energy dispersive X-ray fluorescence (EDXRF) on a total of 366 samples in order to provide detailed elemental composition. Samples have been clustered per campaign and differences were related to backward trajectories. Elements as Cl, Si, and S appeared to be the best tracers for coastal aerosols. Therefore they have been chosen to represent each campaign and to map the seasonal variations. It is clear that Cl is an excellent tracer for oceanic trajectories, while a less clear correlation between the soil dust components and the air mass trajectories is found.

Abstract: The experiments conducted are focused on natural organic substances, removal from water in ion-exchange process, ultrafiltration process and ion exchange-ultrafiltration integrated process. The water from the Odra River and model solution were investigated. In treatment processes, various doses of 5 anion-exchange resins as well as polyethersulphone membranes with different cut-offs were used. The efficiency of process was determined by measuring a decrease both in the colour intensity and the UV 254 nm absorbance. The results show that separation efficiency in integrated process depends on resin dose added to water before ultrafiltration and on the membrane cut-off as well. Among the resins tested the most efficient was MIEX (R) resin. The ion-exchange process carried out prior to the ultrafiltration increased, especially for high cut-off membranes, NOM retention and resulted in the decrease of membrane fouling intensity.

Abstract: Understanding how painted works of art were constructed, layer-by-layer, requires a range of macroscopic and microscopic X-ray and infrared-based analytical methods. Deconstructing complex assemblies of paints horizontally across a picture and vertically through it provides insight into the detailed production process of the art work and on the painting techniques and styles of its maker. The unwanted chemical transformations that some paint pigments undergo are also detectable; these changes can alter the paint's optical properties. Understanding the chemistry behind such paint degradation gives conservators vital clues to counter these effects and is an invaluable asset in protecting these cultural artefacts for future generations.

Abstract: The electrochemical activation of C-X bonds requires very negative electrode potentials. Lowering the overpotentials and increasing the catalytic activity requires intensive electrocatalytic research. A profound understanding of the reaction mechanism and the influence of the electrocatalyst allows optimal tuning of the electrocatalyst. This can be achieved by combining electrochemical techniques with electron paramagnetic resonance (EPR) spectroscopy. Although this was introduced in the mid-twentieth century, the application of this combined approach in electrocatalytic research is underexploited. Several reasons can be listed, such as the limited availability of EPR instrumentation and electrochemical devices for such in situ experiments. In this work, a simple and inexpensive construction adapted for in situ EPR electrocatalytic research is proposed. The proof of concept is provided by studying a model reaction, namely the reductive cyclisation of allyl 2-bromobenzyl ether which has interesting industrial applications.

Abstract: This research is aimed to the study and application of an electrochemical immunosensor for the detection of ovalbumin (OVA) from egg white (or albumen) used as a binder in some works of art, such as some historical photographic prints and tempera paintings. The immunosensor takes advantage of the interesting biodetection capabilities offered by nanoelectrode ensembles (NEEs). The NEEs used to this aim are prepared by template deposition of gold nanoelectrodes within the pores of track-etched polycarbonate (PC) membranes. The affinity of polycarbonate for proteins is exploited to capture OVA from the aqueous extract obtained by incubation in phosphate buffer of a small sample fragment (<1 mg). The captured protein is reacted selectively with anti-OVA antibody, labelled with glucose oxidase (GOx). In the case of positive response, the addition of the GOx substrate (i.e. glucose) and a suitable redox mediator (a ferrocenyl derivative) reflects in the up rise of an electrocatalytic oxidation current, which depends on the OVA amount captured on the NEE, this amount correlating with OVA concentration in the extract. After optimization, the sensor is successfully applied to identify OVA in photographic prints dating back to the late 19th century, as well as in ancient tempera paintings from the 15th and 18th centuries.

Abstract: Electrochemical techniques have evidenced to be highly suitable for the development of portable, rapid and accurate screening methods for the detection of illicit drugs in seized samples. However, the redox inactivity of primary amines, one of the most common functional groups of illicit drugs, masks voltammetric detection in aqueous environment at carbon electrodes and, therefore, leads to false negative results if only these primary amines are present in the structures. This work explores the feasibility of a derivatisation approach that introduces formaldehyde in the measuring conditions in order to achieve methylation, via an Eschweiler-Clarke mechanism, of illicit drugs containing primary and secondary amines, using amphetamine (AMP) and methamphetamine (MET) as model molecules. As a result the electrochemical fingerprint is enriched and thereby the detectability enhanced. A combination of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOFMS) and square-wave voltammetric (SWV) measurements is employed to identify reaction products and link them to the observed redox peaks. Although an alkaline environment (pH 12.0) proved to increase the reaction yield, a richer electrochemical fingerprint (EF) is obtained in neutral conditions (pH 7.0). Similarly, the addition of formate improved the reaction conversion but reduced the EF by eliminating a redox peak that is attributed to side products formed in the absence of formate. To illustrate the applicability, the derivatisation strategy is applied to several prominent illicit drugs containing primary and secondary amines to demonstrate its EF enriching capabilities. Finally, real street samples from forensic seizures are analysed. Overall, this strategy unlocks the detectability of the hitherto undetectable AMP and other drugs only containing primary amines, while strongly facilitating the identification of MET and analogues. These findings are not limited to illicit drugs, the insights can ultimately be applied to other target molecules containing similar functional groups. (C) 2020 Published by Elsevier Ltd.

Abstract: In this work an aptamer-based biosensor is combined with a multisine electrochemical impedance spectroscopy sensing methodology into a novel and promising biosensing strategy. Employing a multisine instead of a traditional single sine measuring method allows the detection and quantification of parameters that provide information about the accuracy and reliability of the results, such as noise and distortions. This does not only lead to a shorter measurement time, but it also enables an easy and fast evaluation of the quality of the data and fitting, leading to more accurate results.

Abstract: This paper presents a previously unexplored biosensing strategy for detecting gliadin which exploits the crosslinking of gliadin with collagen, catalyzed by transglutaminase at the interfacial electron transfer rate, on a modified electrode. The process is monitored by electrochemical impedance spectroscopy using a glassy carbon electrode coated with a collagen layer. To validate the specificity of the response as well as to eliminate possible interferences from other proteins, such as soy protein or casein, the captured gliadin is further reacted with a specific anti-gliadin antibody. Changes in charge transfer resistance, measured from the Nyquist plots, scale linearly with the gliadin concentration in the range 5-20 mg/L, a range suitable for testing the gliadin concentration in gluten-free food commodities.

Abstract: The article describes the use of a fullerene (C60)-β-cyclodextrin conjugate, synthesized via 1,3-dipolar cycloaddition, for the ultrasensitive electrochemical detection of p-nitrophenol. This conjugate was successfully immobilized on the surface of a glassy carbon electrode and the developed device showed high activity towards p-nitrophenol due to the synergetic effect of C60, the latter becoming highly conductive upon reduction. The determination of p-nitrophenol was performed by using square wave voltammetry over a concentration range from 2.8×10−9 mol L−1 to 4.2×10−7 mol L−1 and the detection limit was calculated to be 1.2×10−9 mol L−1.

Abstract: The peanut allergen Ara h 1 belonging to the vicilin family of seed storage proteins is known to be a suitable marker for peanut detection in foods. In the present work, we suggest an electrochemical detection of Ara h 1 using a recently selected 80-base DNA aptamer. The detection strategy relies on insulation effect of a bulky protein captured by an immobilized aptamer. The electrodes were modified by the aptamer and characterized using electrochemical impedance spectroscopy (EIS). The aptamer surface density and analytical parameters of the calibration curves for Ara h 1 were compared with the system prepared with thrombin binding aptamer (TBA) and operated in the same conditions.

Abstract: The Eulerian Chemistry-Transport Model BelEUROS was used to calculate the concentrations of airborne PM10 and PM2.5 over Europe. Both primary as well as secondary particulate matter in the respirable size-range was taken into account. Especially PM2.5 aerosols are often formed in the atmosphere from gaseous precursor compounds. Comprehensive computer codes for the calculation of gas phase chemical reactions and thermodynamic equilibria between compounds in the gas-phase and the particulate phase had been implemented into the BelEUROS-model. Calculated concentrations of PM10 and PM2.5 are compared to observations, including both the spatial and daily, temporal distribution of particulate matter in Belgium for certain monitoring locations and periods. The concentrations of the secondary compounds ammonium, nitrate and sulfate have also been compared to observed values. BeIEUROS was found to reproduce the observed concentrations rather well. The model was applied to assess the contribution of emissions derived from the sector agriculture in Flanders, the northern part of Belgium, to PM10- and PM2.5-concentrations. The results demonstrate the importance of ammonia emissions in the formation of secondary particulate matter. Hence, future European emission abatement policy should consider more the role of ammonia in the formation of secondary particles