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A device comprising a zirconium-based metal–organic framework (MOF) mixed-matrix membrane (MMM) framed in a plastic holder has been used to monitor the content of personal care products (PCPs) in cosmetic samples. Seven different devices containing the porous frameworks UiO-66, UiO-66-COOH, UiO-67, DUT-52, DUT-67, MOF-801, and MOF-808 in polyvinylidene fluoride (PVDF) membranes were studied. Optimized membranes reach high adsorption capacities of PCPs, up to 12.5 mg·g–1 benzophenone in a 3.0 mg·L–1 sample. The MMM adsorption kinetics, uptake measurements, and isotherm studies were carried out with aqueous standard solutions of PCPs to ensure complete characterization of the performance. The studies demonstrate the high applicability and selectivity of the composites prepared, highlighting the performance of PVDF/DUT-52 MMM that poses uptakes up to 78% for those PCPs with higher affinity while observing detection limits for the entire method down to 0.03 μg·L–1. The PVDF/DUT-52 device allowed the detection of parabens and benzophenones in the samples, with PCPs found at concentrations of 1.9–24 mg·L–1.

On 10 October 2011, a submarine volcanic eruption began 2 km south of the island of El Hierro (Canary Islands, Spain). It was the first eruption after 40 years of quiescence in the Canarian archipelago. Since mid-July 2011, a multiparametric network has been deployed by the Instituto Geográfico Nacional (hereinafter IGN)to monitor volcanic processes. The data recorded by five stations, measuring the air and soil temperature, CO and radon concentration in the air inside four galleries and one well, are the focus of the present paper. Two important anomalies were found that improve comprehension of the volcanic process. First, a clear increase in CO concentration in one gallery (from 825 ± 19 to 2305 ± 35 ppm)which seems to be mainly controlled by ground deformation measured during the unrest period preceding the eruption. Second, a relationship between radon concentration in air in a well located in the northern side of the island with seismic energy release (several peaks with up to 115% increase), and ground deformation (50% growth in background level), also before the eruption onset. Lastly, changes in radon concentration during eruptive period seem to be modulated by seismic activity (increases up to 233%), which in turn is likely related to variations in magma rheology.

Silver nanoparticles (AgNPs) present unique physical and chemical properties such as chemical stability, huge superficial area and excellent optical properties, thus justifying the impact and variety of their applications: in material science, in electrochemistry, in electronic devices, as biological or chemical sensors, and in catalysis. Given the fact that there is a limited number of studies on synthesis of AgNPs compared with other nanomaterials, this article proposes a simple methodology for synthesizing AgNPs involving the wet chemical reduction of silver nitrate with gallic acid as a reduction/capping reagent. The reaction is carried out in absence or in presence of hydrogen peroxide; and the formation of AgNPs is monitored by UV–vis and fluorescence spectroscopy. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were used for further characterization. Two main types of nanoparticles/nanodiscs were clearly identified in absence and in presence of hydrogen peroxide, respectively. Thus, AFM revealed the formation of AgNPs of 18.15 ± 1.95 nm in diameter and of 2.21 ± 0.35 nm high or of 9.16 ± 1.28 nm in diameter and of 1.57 ± 0.17 nm high. The STM technique revealed that average particle size was 4.59 ± 0.61 nm with hydrogen peroxide and 3.84 ± 0.66 nm without it. Therefore, the nanoparticle size obtained by AFM was strongly influenced by the capping thickness. The reduction in nanoparticle size was accompanied by increased uniformity and reproducibility. The fluorescence of the AgNPs was used to determine traces of iron in tap water and bottled water via an induced fluorescence quenching mechanism, thus aiding in establishing an analytical method.

Authors propose a novel braid support configuration for use in solid-phase microextraction (SPME) fibers. Two different braided supports (double and triple) were prepared and compared with the conventional single support configuration. Three kinds of silver-based nanomaterials that serve as coatings on these supports are described. They included silver dendrites, silver nanoparticles (AgNPs), and silver dendrites decorated with AgNPs (Ag-dendrites@AgNPs). They were prepared by electrodeposition, a layer-by-layer (LBL) method, and a hybrid strategy, respectively. Fibers were used in the direct-immersion (DI) mode of SPME. Five polycyclic aromatic hydrocarbons (PAHs) were studied as model analytes by DI-SPME when analyzing (spiked) underground waters. PAHs were further determined with high-performance liquid chromatography (HPLC) and fluorescence detection. The analytical performance of the fibers was compared to that of the commercial polydimethylsiloxane (PDMS) fiber of 100 μm thickness. AgNPs obtained by LBL was the best coating and the double braid was the best support configuration. The configuration of the SPME support always played an important role independently on the coating material, being always beneficial the use of double-braids. Despite the low coatings volumes of the silver-based fibers compared to that of PDMS, the analytical features of the method were adequate. Figures of merit include: (a) limits of detection down to 20 ng·L−1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) of 60 extractions).

In Tenerife there are a vast number of sub-horizontal blind water mines, called “galleries”. Seven air and soil temperatures and CO2 concentration profiles in air were carried out inside the Río de Guía gallery (hereinafter RdG). An anomalous stable maximum temperature point (hereinafter MTP) was found around 2000 m from the entrance. During the warm period, a clear CO2 stagnation was detected before MTP, showing concentrations up to 14,000 ppm. In order to study gas emission and its dynamics inside the gallery, four stations were deployed around MTP. All stations recorded air and soil temperatures, and CO2 and Rn concentration in air from November 2009 to January 2011. After analyzing this dataset, it was possible to characterize the influence of MTP. This thermal anomaly divided the gallery into two sections. In the cold period, the outer section located outwards from MTP became colder while the inner section warmed up owing to a less heat transfer into the deepest part of the gallery. There were several short periods when variations in barometric pressure created an advection movement that was able to temporally change the gas behavior inside the gallery. Two soil gas samples were taken around MTP and their δ13C (CO2) ratios suggested a magmatic origin. All data were combined to create a model for the gas and thermal dynamics inside the gallery. This model, together with identification of background levels in each parameter, allows to identify any anomalous signal that could be elated with changes in volcanic activity., This study was funded by the Instituto Geográfico Nacional (Ministerio de Fomento, Spanish Government).

Core-shell SiO2@CIM-80(Al) microspheres were synthesized, characterized, and used as novel sorbent in a dispersive miniaturized solid-phase extraction (D-μSPE) method for the determination of fourteen polycyclic aromatic hydrocarbons (PAHs) in wastewaters by ultra-high performance liquid chromatography coupled to a fluorescence detector (UHPLC-FD). A Doehlert experimental design permitted to optimize the main parameters affecting the microextraction procedure, intending the obtaining of a simple approach. Optimized extraction conditions include 13 mg of SiO2@CIM-80(Al) microparticles (~2 mg CIM-80(Al)), 2.5 min of extraction time, 0.125 mL of acetonitrile (ACN) as desorption solvent and 0.5 min of desorption time. The entire method showed adequate analytical performance with limits of detection down to 5 ng L−1, and inter-day precision lower than 14.1% for a concentration level of 0.5 μg L−1. The extraction capability of SiO2@CIM-80(Al) microspheres was compared to that obtained with commercially available silica microspheres and the neat MOF CIM-80(Al), demonstrating the advantages of the use of MOF core-shell sorbents in D-μSPE.

The authors describe a new coating for use in solid-phase microextraction (SPME). Silver nanoparticles (AgNPs) were prepared by using gallic acid or glucose as the reducing agents, and then supported onto a stainless steel wire that was previously coated with a silver mirror. Coating with AgNPs was performed by a layer-by-layer approach of up to eight cycles of consecutive deposition of AgNPs and the thiol linker 1,8-octanedithiol. This procedure allows proper control of the coating thickness. Thicknesses are 3.2 μm and 3.5 μm with AgNPs obtained with gallic acid and glucose, respectively. This is in agreement with theoretical estimations (3.8 μm). The fibers were used in the direct-immersion SPME-GC-FID determination of 16 polycyclic aromatic hydrocarbons (PAHs) from different waters. The performance of the method was compared to the one using polydimethylsiloxane fibers (100 μm), which is the most suitable commercial SPME fiber for PAHs. Despite the low thickness of the AgNP coatings (compared to PDMS), the analytical features of the method using the most adequate coating (AgNPs prepared with gallic acid) include: (a) limits of detection down to 0.6 ng·mL−1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) lower than 22, 26 and 25%, respectively; and (c) an operational lifetime of ~150 extractions/desorption cycles. The analysis of various spiked environmental waters using these fibers resulted in adequate analytical performance.

Free fatty acids and sensory profiles were obtained for cheeses made with raw goat milk and vegetable coagulant, derived from the cardoon flower ( Cynara cardunculus), at different ripening times (7 and 20 days). A solid–liquid phase extraction method followed by solid-phase extraction and gas chromatography was used. Profiles were also obtained with cheeses made with commercial coagulant, traditional kid rennet paste, and mixture coagulant (vegetable coagulant-kid rennet). The use of vegetable coagulant and vegetable coagulant-kid rennet is common in traditional Protected Designation of Origin cheeses such as “ Queso Flor de Guía” and “ Queso Media Flor de Guía” (Spain). Contents of short-chain free fatty acids (7.5–22.5 mmol·kg−1), medium-chain free fatty acids (0.4–3.7 mmol·kg−1), and long-chain free fatty acids (0.2–2.1 mmol·kg−1) varied depending on the coagulant type and the ripening time. Vegetable coagulant cheeses present odour intensity and flavour intensity much higher than commercial coagulant cheeses in the sensory analysis for cheeses obtained with seven days of ripening, but the values decrease when increasing the ripening time. Multivariate analysis allowed us to differentiate cheese samples according to the ripening time when using lipolytic profile and according to the coagulant type using the sensory profile.

The use of solid-phase microextraction coatings based on gold nanoparticles was investigated, focusing the attention on the preparation of nanoparticles with non-classical reduction agents of HAuCl4 such as gallic acid and H2O2, rather than the conventional sodium citrate. All nanoparticles were characterized by diode array spectroscopy, whereas novel nanoparticles prepared with gallic acid and H2O2 were also characterized by microscopic techniques. Solid-phase microextraction coatings were prepared with a layer-by-layer approach. Gallic acid permitted the preparation of stable nanoparticles with milder experimental conditions (1 min, room temperature) and provided the most uniform coatings (thickness ∼3 μm). Seven organochlorine pesticides were determined in different environmental waters using gas chromatography with electron capture detection. Despite the low thickness of the coatings, limits of detection of the entire method down to 0.13 μg·L−1 were obtained. A comparison with the commercial polyacrylate in terms of the partition coefficients of the analytes to the coatings gave logarithm of the partition coefficient values two times higher with gallic acid than polyacrylate (although the commercial fiber is 28 times thicker). Inter-fiber relative standard deviation values ranged from 8.67 to 21.3%. Optimum fibers also presented an adequate lifetime (>100 extractions). This article is protected by copyright. All rights reserved