Impact of "chemical cocktails" exposure in shaping mice gut microbiota and the role of selenium supplementation combining metallomics, metabolomics, and metataxonomics

Biological systems are exposed to a complex environment in which pollutants can interact through synergistic or antagonistic mechanisms, but limited information is available on the combined effects. To this end, conventional and antibiotic-treated (Abx) mice models were fed regular rodent or selenium (Se) supplemented diets and exposed to a "chemical cocktail" (CC) including metals and pharmaceuticals. Metallomics, metabolomics, and metataxomics were combined to delve into the impact on gut microbiota, plasma selenoproteome, metabolome, and arsenic metabolization. At the molecular level, Se decreased the concentration of the antioxidant glutathione peroxidase in plasma and increased the arsenic methylation rate, possibly favoring its excretion, but not in the Abx and also plasma metabolomes of Abx, and Abx-Se were not differentiated. Moreover, numerous associations were obtained between plasma selenoproteins and gut microbes. Se-supplementation partially antagonizes the gut microbiota alteration caused by Abx, and slightly by CC, but strongly altered profiles were observed in CC-Abx-Se, suggesting synergistic deleterious effects between pollutants, Abx and Se. Moreover, although CC and Abx changed gut microbiota, several common taxa were enriched in CC-Abx and control mice, indicating possible synergistic effects. Our results suggest a potential beneficial impact of supplementation, but mediated by gut microbes being reversed in their absence.

Effervescence-assisted spiral hollow-fibre liquid-phase microextraction of trihalomethanes, halonitromethanes, haloacetonitriles, and haloketones in drinking water

A new analytical method was optimized to determine 18 disinfection by-products (DBPs) in drinking water, including four different chemical groups. For this purpose, spiral-shaped hollow-fibre liquid phase microextraction with 1-octanol as the acceptor solvent assisted by effervescence was applied using a homemade supporting device that was specifically designed for this application. The device was printed in a 3D printer and allows for an increased fibre surface even with a low sample volume, which significantly facilitates the extraction. The samples were analysed by gas chromatography coupled to both an electron capture detector and a mass spectrometer for the quantification and unequivocal identification of the analytes, respectively. Effervescence was generated using citric acid and bicarbonate at a molar ratio 1:2, which significantly improves the extraction efficiency and reduces mechanical operations, since stirring and modifiers are not required. The results showed enrichment factors ranging from 13.1 to 140.1. Satisfactory recoveries (80-113 %) were obtained, with relative standard deviations from 3 to 15 % and good linearity. The detection limits (ng L^-1) ranged from 10 to 35 (trihalomethanes), 12 to 220 (halonitromethanes), 17 to 79 (haloacetonitriles) and 10 to 16 (haloketones). The applicability of the method was assessed in 6 local water distribution systems.

A novel HPLC column switching method coupled to ICP-MS/QTOF for the first determination of selenoprotein P (SELENOP) in human breast milk

In this work, we describe for the first time the presence of selenoprotein P in human breast milk. To this end, a novel analytical method has been developed based on a two-dimensional column switching system, which consisted of three size exclusion columns and one affinity column coupled to inductively coupled plasma mass spectrometry (ICP-MS). The method combines the accurate quantification of selenoproteins and selenometabolites by species unspecific isotopic dilution ICP-MS, with unequivocal identification by quadrupole-time-of-flight mass spectrometry. Several selenopeptides, which contain the amino acid selenocysteine (U, SeCys), were identified after tryptic digestion followed by their separation. The results reveal that the relative selenium concentration in colostrum follows the order: glutathione peroxidase (GPX) ≈ selenoprotein P (SELENOP) > selenocystamine (SeCA) > other selenometabolites (SeMB), in contrast with previously published papers (GPX > SeCA > selenocystine > selenomethionine). A mean concentration of 20.1 ± 1.0 ng Se g^-1 as SELENOP (1.45 μg SELENOP/g) was determined in colostrum (31% of total selenium).

Seasonal and spatial evolution of trihalomethanes in a drinking water distribution system according to the treatment process

This paper comparatively shows the influence of four water treatment processes on the formation of trihalomethanes (THMs) in a water distribution system. The study was performed from February 2005 to January 2012 with analytical data of 600 samples taken in Aljaraque water treatment plant (WTP) and 16 locations along the water distribution system (WDS) in the region of Andévalo and the coast of Huelva (southwest Spain), a region with significant seasonal and population changes. The comparison of results in the four different processes studied indicated a clear link of the treatment process with the formation of THM along the WDS. The most effective treatment process is preozonation and activated carbon filtration (P3), which is also the most stable under summer temperatures. Experiments also show low levels of THMs with the conventional process of preoxidation with potassium permanganate (P4), delaying the chlorination to the end of the WTP; however, this simple and economical treatment process is less effective and less stable than P3. In this study, strong seasonal variations were obtained (increase of THM from winter to summer of 1.17 to 1.85 times) and a strong spatial variation (1.1 to 1.7 times from WTP to end points of WDS) which largely depends on the treatment process applied. There was also a strong correlation between THM levels and water temperature, contact time and pH. On the other hand, it was found that THM formation is not proportional to the applied chlorine dose in the treatment process, but there is a direct relationship with the accumulated dose of chlorine. Finally, predictive models based on multiple linear regressions are proposed for each treatment process.

Combined use of total metal content and size fractionation of metal biomolecules to determine the provenance of pine nuts (Pinus pinea)

Four essential elements (Mn, Ni, Zn, and Cu) and their molecular-size distribution patterns have been determined, for twenty four samples of pine nuts from eight areas in Spain and Portugal (Huelva, Cádiz, Badajoz, Cataluña, Castilla, Madrid, Faro, and Coimbra), by size-exclusion liquid chromatography (SEC) coupled on-line to UV and inductively coupled plasma mass spectrometric (ICP-MS) detection. The variability observed in total element content and the size-exclusion profiles of elements in samples from distant areas were considered as chemical descriptors for characterization of geographic origin. A pattern-recognition technique, the display method principal component analysis, was used as visualization technique to determine the provenance of the pine nuts collected. The results obtained confirmed that size fractionation profiles give more information for assessing the provenance of pine nuts than the total elements composition traditionally used for this purpose. Combination of these chemical descriptors was the most suitable choice for the samples studied. Figure This paper shows the application of an analytical approach based on total elements concentrations and the relative abundance of metal-biomolecules, estimated by the size-exclusion fractions, as chemical descriptors to determine the provenance of pine nuts. Principal component analysis (PCA) has been used as a visualization technique.

Comparative study of electrospray and photospray ionization sources coupled to quadrupole time-of-flight mass spectrometer for olive oil authentication

The use of fast and reliable analytical procedures for olive oil authentication is a priority demand due to its wide consumption and healthy benefits. Olive oil adulteration with other cheaper vegetable oils is a common practice that has to be detected and controlled. Rapid screening methods based on high resolution tandem mass spectrometry constitute today the option of choice due to sample handling simplicity and the elimination of the chromatographic step. The selection of the ionization source is critical and the comparison of their reliability necessary. The possibilities of the direct infusion electrospray ionization (ESI) and the recently introduced atmospheric pressure photospray ionization source (APPI), coupled to quadrupole time-of-flight (QqTOF), have been critically studied and compared to control olive oil adulteration. These techniques are very rapid (approximately 1min per sample) and have high discrimination power to elucidate key components in the edible oils studied (olive, hazelnut, sunflower and corn). Nevertheless, both sources are complementary, being APPI more sensitive for monoacyl- and diacylglycerol fragment ions and ESI for triacylglycerols. In addition, methods reproducibility's are very high, especially for APPI source. Mixtures of olive oil with the others vegetable oils can be easily discriminated which has been tested by using principal components analysis (PCA) with both ESI-MS and APPI-MS spectra. Analogously, linear discriminant analysis (LDA) confirms methods reproducibility and detection of other oils used as adulterants, in particular hazelnut oil, which is especially difficult given its chemical similarity with olive oil.

Multielemental fractionation in pine nuts (Pinus pinea) from different geographic origins by size-exclusion chromatography with UV and inductively coupled plasma mass spectrometry detection

Pine nuts (Pinus pinea) from different geographical origin in Spain and Portugal have been investigated concerning total element content and metal-biomolecules size distribution patterns Mn, Zn, Ni and Cu. All the studied metals were at the highest concentration in pine nuts from Faro and at the lowest from Cataluña. The most abundant element in samples was Mn at concentrations in the range of 26 microg g(-1) (Cataluña) to 559 microg g(-1) (Faro). Zn was also present at high concentration in samples, from 25 microg g(-1) (Cataluña) to 113 microg g(-1) (Faro). To a deeper insight to obtain classification rules for samples, pine nuts were analyzed by size-exclusion chromatography (SEC) with UV detection and inductively coupled plasma mass spectrometry (ICP-MS). Two columns were used covering the molecular weigh range from < 10 to 70 kDa that allowed the discrimination of the studied samples. Data reveal that the most differential UV-profile with low molecular weight (LMW) column was obtained with pine nuts from Huelva. This column allows good discrimination in the range of 2126-1352 Da in which a lot of peaks can be used to differentiate samples. The UV profiles obtained with the high molecular weight (HMW) column allows a poorer differentiation of samples, but pine nuts from Huelva, Castilla and Madrid are clearly distinguished to the others. In relation to fractionation patterns of metals, Mn allows a good discrimination between samples (LMW column), Cu was the only one associated to fractions at MW > 70 kDa in sample from Cádiz, and profiles of Ni and Zn are clearly different in terms of abundance of peaks. All these chromatographic profiles for elements give valuable information about the geographical origin of the studied samples and the differences found are discussed in this work.

Use of flow injection atmospheric pressure photoionization quadrupole time-of-flight mass spectrometry for fast olive oil fingerprinting

The recently introduced technique of an atmospheric pressure photoionization (APPI) source coupled to quadrupole time-of-flight mass spectrometry (QqTOFMS) has been applied to fast olive oil fingerprinting on the basis of the accurate mass measurements obtained with this instrumentation. The key compounds can be characterized as [M+H]+ (produced by proton transfer) or as [M]+* (by charge transfer) ions in the mass spectra. [M+H]+ ions, however, show higher abundance, especially for triacylglycerols. Other ions present in APPI-MS are the acylium ion [RiCO]+ and [RiCO-H2O]+. This latter ion is absent in the electrospray ionization (ESI)-MS spectra, and this represents valuable complementary information. Several critical parameters in the APPI source were optimized such as LC eluent composition, ion spray voltage and, especially, declustering potential. APPI-QqTOFMS allows easy discrimination among different edible oils: olive, extra virgin olive, olive-pomace, hazelnut, sunflower, corn and several mixed oils, with high throughput (approximately 1 min per sample). Cluster analysis was applied to obtain the best experimental conditions for oil discrimination on the basis of declustering potential. Principal components analyses of these APPI-MS spectra show that the approach can be used for studies of olive oil adulteration with other oils, even in the case of hazelnut oil that exhibits a high chemical similarity with olive oil.