Volume 69, Issue 6

The provenance of obsidian artefacts and raw materials was studied by the multivariate statistical analysis of forty-five samples using elemental composition data obtained by laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS). One ICP-MS instrument equipped with a quadrupole mass filter and the other based on a time-of-flight analyser were coupled to the same type of laser ablation device (Nd:YAG 213 nm), thereby affording a comparison of the different mass spectrometers in terms of precision and verification of the consistency of the results. The influence of surface roughness (polished raw material vs artefact) and microinhomogeneity on the LA-ICP-MS signal was studied under the optimised working conditions of the laser ablation device. Principal component analysis, correspondence analysis, independent component analysis, multi-dimensional scaling, Sammon mapping and fuzzy cluster analysis were applied and compared in order to reveal statistically significant compositional differences between particular geological sites and to disclose the provenance of the raw materials used in manufacture of the artefacts. Twenty-seven artefacts and eighteen raw material samples from natural resources in the Czech Republic, Slovakia, Italy, Greece, Syria, Iraq, Turkey, Mexico and Nicaragua were examined with special attention focused on samples from Moravia (Czech Republic) and some Near East sites (Tell Arbid, Tell Asmar). The Carpathian origin of the obsidian artefacts was investigated in the Moravian samples using the Pb, Rb and U contents. The Near East samples were classified according to their Sr, Ba, Zr and REE contents as per-alkaline obsidians (Bingöl A/Nemrut Dağ) originating from Southeast Anatolia.

A simple, fast, and sensitive method for speciation and determination of As (III, V) and Hg (II, R) in human blood samples based on ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) and flow injection hydride generation/cold vapor atomic absorption spectrometry (FI-HG/CV-AAS) has been developed. Tetraethylthiuram disulfide, mixed ionic liquids (hydrophobic and hydrophilic ILs) and acetone were used in the DLLME step as the chelating agent, extraction and dispersive solvents, respectively. Using a microwave assisted-UV system, organic mercury (R-Hg) was converted to Hg(II) and total mercury amount was measured in blood samples by the presented method. Total arsenic content was determined by reducing As(V) to As(III) with potassium iodide and ascorbic acid in a hydrochloric acid solution. Finally, As(V) and R-Hg were determined by mathematically subtracting the As(III) and Hg(II) content from the total arsenic and mercury, respectively. Under optimum conditions, linear range and detection limit (3σ) of 0.1-5.0 μg L −1 and 0.02 μg L −1 for As(III) and 0.15-8.50 μg L −1 and 0.03 μg L −1 for Hg(II) were achieved, respectively, at low RSD values of < 4 % (N = 10). The developed method was successfully applied to determine the ultratrace amounts of arsenic and mercury species in blood samples; the validation of the method was performed using standard reference materials.

A method for the determination of formaldehyde by flow injection analysis with spectrophotometric detection is proposed, based on retarding the reaction between brilliant green and sulphite by the addition of formaldehyde; this was investigated for formaldehyde quantification in extracts from wood-based panels. For the first time, a heating step was explored, providing a sample throughput of 50 analyses per hour, with a limit of detection of 0.02 mg L −1 and linearity of 0.20-3.0 mg L −1 , which was adequate for the expected range of formaldehyde concentration in the extracts. The mean recovery observed for actual samples was in the range of 92-106 %, with a maximum relative standard deviation of 6.0 %. The paired t-test revealed no significant difference between this method and the official Nash method, demonstrating an appropriate accuracy and precision; the method is proposed as a simple, fast and inexpensive alternative for the routine determination of formaldehyde in an aqueous medium.

The investigation of air pollution is a highly important field of research. Air quality in a vehicle’s interior has attracted growing attention since people spend much of their time in vehicles and those frequently travelling in new cars are exposed to harmful compounds. The main air pollutants inside new vehicles are volatile organic compounds (VOCs), present as a result of interior materials’ de-gassing. Among the sampling methods used in indoor air quality research, active sampling for VOCs collection is one method that has been extensively described and applied. The present study sought to implement passive sampling with Radiello ® samplers to collect air samples directly in the car factory. The results from passive sampling were compared with results derived from active sampling using Carbograph 1TD and silicagel coated with 2,4-dinitrophenylhydrazine cartridges, based on previously validated methods. The identification and quantification of organic compounds was performed using gas chromatography with flame ionisation coupled with a mass spectrometer after thermal desorption. Aldehydes were determined by means of high-performance liquid chromatography. In the present study, the results obtained with the use of active and passive methods of air sampling were compared, correlations between the two sampling methods were designated and the repeatability of passive sampling was detailed.

A low-temperature mini-emulsion medium for the enzymatic resolution of 1-phenylethanol is described for the first time. The enzymatic hydrolysis resolution of 1-phenylethyl esters with different chain-lengths in the presence of Candida antarctica lipase B in mini-emulsion media was shown to be significantly controlled by temperature. In this system, the direct effect of temperature on the mini-emulsion size was observed. For the longer 1-phenylethyl ester, 1-phenylethyl dodecanoate, the enzymatic resolution was promoted exclusively at low temperatures. The preparative mini-emulsion enzymatic reaction of 1-phenylethyl dodecanoate at 4°C afforded the isolation of (R)-phenylethanol with a yield of 36 % with an ee of 99 %. (S)-Phenylethanol was isolated with a 51 % yield with an ee of 79 %.

Ce-Ti-W-O x catalysts were prepared and applied to the NH 3 -selective catalytic reduction (SCR) reaction. The experimental results showed that the Ce-Ti-W-Ox catalyst prepared by the hydrothermal method exhibited higher NO conversion than those synthesised via the sol-gel and impregnating methods, while the optimal content of WO 3 and molar ratio of Ce/Ti were 20 mass % and 4 : 6, respectively. Under these conditions, the catalyst exhibited the highest level of catalytic activity (the NO conversion reached values higher than 90 %) across a wide temperature range of 225-450◦C, with a range of gas hourly space velocity (GHSV) of 40000-140000 h −1 . The catalyst also exhibited good resistance to H 2 O and SO 2 . The influences of morphology, phase structure, and surface properties on the catalytic performance were investigated by N 2 adsorption-desorption measurement, XRD, XPS, H 2 -TPR, and SEM. It was found that the high efficiency of NO removal was due to the large BET surface area, the amorphous surface species, the change to element valence states, and the strong interaction between Ce, Ti, and W.

Catalytic wet peroxide oxidation (CWPO) of m-cresol over Fe/γ-Al 2 O 3 and Fe-Ce/γ-Al 2 O 3 was studied. Catalysts were prepared using the incipient wetness impregnation method, and characterized using XRD, XPS, BET, and SEM techniques. Effects of Ce loading, H 2 O 2 dose, initial solution pH, reaction temperature, and m-cresol concentration on the CWPO of m-cresol were investigated in detail. The results showed that an addition of 2 mass % Ce into Fe/γ-Al 2 O 3 resulted in better catalytic activity over a wider pH range and at lower reaction temperatures, and with lower H 2 O 2 consumption than when using the Fe/γ-Al 2 O 3 catalysts only. The best catalytic activity was obtained using the Fe-Ce-2 catalyst with complete m-cresol degradation, 43.2 % TOC removal using 100 mmol L −1 H 2 O 2 at pH 4.0 and 60°C in 90 min. XPS showed that an addition of 2 mass % Ce increased the density of non-lattice oxygen on the catalyst surface facilitating electron transfer and thereby producing radicals and promoting catalytic activity in the CWPO reaction. Recycling experiments showed that Fe-Ce-2 retained its activity even after six subsequent runs without changing the morphology, and that iron ions did not significantly leach from the catalyst surface.

Two types of graphene oxide-TiO 2 composites were prepared: one by including graphene oxide flakes in the TiO 2 sol, followed by thermal treatment (GI composite) at 300°C, and the second by including graphene oxide flakes in the calcined (at 500°C) TiO 2 xerogel (GII composite). The composites were characterized by SEM, TEM-EDS, TEM-SADP, STEM-HAADF, HRTEM coupled with FT, XRD, and XPS. Photocatalysis results were fitted to different kinetic models (pseudo-first and pseudo-second kinetics, intraparticle Weber-Morris diffusion, film diffusion, and external mass transfer). The results showed that by introducing graphene oxide flakes in the TiO 2 sol, followed by thermal treatment at 300°C (GI composite), an efficient graphene oxide-TiO 2 catalyst with high specific surface area, heterogeneity, and many graphitized areas can be obtained. Complete crystallization of the composite is not the key issue for the best photoactivity achievement. The rate limiting step in the photocatalytic process is the photooxidation of SA molecules on the TiO 2 surface.

Analcime shell-nickel ferrite core microspheres were decorated with Pd and Pt nanoparticles with the aid of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The samples thus prepared were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) methods. The XRD patterns confirmed the growth of a zeolitic layer on the surface of the magnetic cores. The thermogravimetric analysis (TGA) curve clearly indicated the thermal decomposition of the loaded IL, which confirmed the presence of BMIM-PF6 in the structures. In addition, EDX analysis indicated that the samples contained 2.5 mass % of noble metal. The metallic species can be adsorbed on the modified surface and/or penetrate into the zeolitic channels in the structures. The results indicate that the X-IL/An/S/NF (X = Pt or Pd) metallic nanoparticles supported core-shell catalystssamples were able to catalyse the selective oxidation of cyclohexene to 2-cyclohexene-1-ol under the induced conditions. The catalysts continued to be active after recycling up to 5 times. Eventually, a suitable mechanism was proposed for the selective oxidation of cyclohexene over the catalysts.

A new type of coagulant, polysilicate-ferric-zinc (PSFZn) with different Fe/Zn molar ratios, was synthesised using water glass (industrial grade, w(SiO 2 ) = 21 mass %, ρ = 1.34 × 10 3 kg m −3 , modulus = 3.2), FeSO 4 · 7H 2 O, ZnSO 4 , and NaClO 3 by way of co-polymerisation in the same (Fe + Zn)/Si molar ratio based on polysilicate-ferric (PSF). The effect of the Fe/Zn molar ratios on the morphology and structure was systematically investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. Three samples, namely PSFZn4, PSFZn1, and PSFZn0.25, represented Fe/Zn molar ratios of 4, 1, and 0.25, respectively, and were selected for a comparative study while a constant (Fe + Zn)/Si molar ratio equal to 1 was maintained. Accordingly, PSFZn was found to be a complex compound rather than a simple mixture of raw materials. With the decrease in Fe/Zn, a great change occurred in the surface morphology, from a tetrahedral cluster structure to a lamellar structure. The Fe-O and Fe-O-Si bonds were gradually replaced by Zn-O and Zn-O-Si. However, the crystalline peaks were more obvious with the increase in the number of zinc ions; hence the new polymer would be formed from iron, zinc, and polysilicate. In addition, the coagulation performance of PSFZn was investigated using a surface water sample. PSFZn4 exhibited a better coagulation performance than the other PSFZn coagulants. Additionally, the trends in changes in pH with different coagulation times after adding PSFZn were studied relative to PSF and FS. The replacement of zinc ions with iron ions could effectively counter the rapid decrease in pH. The effect of settling time on the coagulation efficiency was also investigated. PSFZn4 exhibited a better settlement performance than PSF and poly aluminium chloride (PAC). Hence, the partial substitution of zinc salt with iron salt not only addresses the inadequacies of iron salt but also improves the coagulation efficiency of zinc salt in water treatment.

The rosemary extract was encapsulated in polyethylene or in covalently-based network gels. The covalent gels were obtained by the reaction of isocyanate end-capped polyethylene glycol (PEG) with β-cyclodextrin or glycerol. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to evaluate the antioxidant activity (AA) of rosemary extract entrapped in polymeric structures and in ethanol or water solutions. The AA of the rosemary extract was determined using a DPPH radical for samples prepared in ethanol, and a water-soluble derivative, the sulphonated DPPH radical (DPPH-SO3Na), for the rosemary extract in water. Formulation of the rosemary extract in polymeric gels ensures a rapid release which determines the AA values similar to those in solution.

Thirteen cultivars of sea buckthorn (Hippophae rhamnoides L.) berries: Aromat, Botanicky, Buchlovicky, Hergo, Krasavica, Leicora, Ljubitelna, Pavlovsky, Peterbursky, Sluničko, Trofinovsky, Vitaminnaja and Velkoosecky, were tested for the content of volatile aroma compounds using gas chromatography with the solid phase microextraction method during two consequent years (2012- 2013). In total, 69 volatile compounds were identified: 26 alcohols, 12 aldehydes, 11 ketones, 9 acids and 11 esters. Based on principal component analysis, 18 most relevant compounds, best representing the variability of the whole system and suitable for the discrimination of the samples, were selected from all compounds identified. These compounds were then compared using the analysis of variance to confirm differences between the samples. Significant (p < 0.05) differences were found in the varieties in both years, Krasavica and Sluničko cultivars were found to be quite different from other varieties, being rich in the compounds identified and containing most of the selected compounds. Variability within the cultivars (between picking years) was low or not significant.

Carbon-sulfur-bridged glycomimetics were prepared by free radical hydrothiolation of the exocyclic double bond of unsaturated sugars. Reaction between benzoyl-substituted pyranoid-exoglycal and a range of thiols including peptide, 1-thioglycerol and 1-thiosugar derivatives gave β-Dconfigured carbon-sulfur-linked glycoconjugates with full stereoselectivity. Addition of a panel of thiols to a 3-exomethylene-glucofuranose derivative also proceeded in a stereoselective manner and afforded a series of D-allo-configured 3-deoxy-3-C-S-bridged glycoconjugates.

Ethyl acetoacetate-sugar derivatives were prepared by standard alkylation of primary or secondary hydroxyls of diacetonide-protected sugars with ethyl 4-chloroacetoacetate. The obtained d-fructose, d-galactose, d-glucose and d-allose derivatives were conjugated to C 60 using the Bingel reaction to afford hydrolytically stable, ether-linked fullerene-carbohydrates. Conjugation of an ester-protected mannose derivative to the C 60 scaffold was carried out by the combination of the acetoacetate chemistry with the azide-alkyne click reaction.