Asier Vallejo

Asier Vallejo
Universidad del País Vasco / Euskal Herriko Unibertsitatea | UPV/EHU · Analytical Chemistry

PhD

About

54
Publications
12,305
Reads
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1,356
Citations
Additional affiliations
August 2007 - present
Universidad del País Vasco / Euskal Herriko Unibertsitatea
Position
  • Lecturer
August 2007 - present
Universidad del País Vasco / Euskal Herriko Unibertsitatea
Position
  • Lecturer

Publications

Publications (54)
Article
Full-text available
The interest in the identification of animal species housed in caves or rock-shelters used as livestock pen and herding management along prehistoric and historic ages, is increasing to understand better the development of pastoral activities. In this manuscript, a method for the quantification of β-sterol/phytosterols, bile acids, hormones and horm...
Chapter
Biomarkers of fecal origin are useful in identifying animal husbandry. In this chapter, two different analytical strategies based on liquid and gas chromatography (LC-MS and GC-MS) were used to detect and quantify several biomarkers suitable for obtaining information regarding animal husbandry in fumier deposits from El Mirador cave (Sierra de Atap...
Article
Full-text available
The application of biostimulants appears to be an environmentally friendly, innovative, and sustainable agronomical tool to mitigate the negative effects induced by adverse climatology in traditional grape-growing regions such as La Rioja (Spain). However, their mechanism of action in grapevines is still unclear. We evaluated how commercial substan...
Article
Early husbandry practices that include herd management and the use of livestock areas such as sheepfold caves can be analysed in the context of different disciplines (e.g. zooarchaeology, micromorphology, and archaeobotany). In this study, a new and standard method for the determination of bile acids and steroidal hormones that incorporates microwa...
Article
Faecal matter is commonly recovered from archaeological sites related to human/animal activity. The identification of its source is essential to understand the domestication process and the relationship between humans and domestic animals in ancient times. Additionally, faecal matter is useful for determining the diet of animals. Therefore, the use...
Article
Currently, aluminum stub with carbon adhesive devices are used to collect inorganic gunshot residues (GSR) from the hands of a shooter. In an ideal shooting case, the gunshot particles do not persist for more than 2 h in the hands of the shooter, provided that the hands have not been washed. However, for forensic analysis and inference, the extende...
Article
Systematic fungicides treatments in vine-growing European ecosystems have been conducted for decades. The goal of this study was to determine the mobility and persistence of 20 fungicides used in two viticultural zones in Atlantic and Mediterranean climates, from the moment of their application until their distribution throughout different compartm...
Article
Full-text available
Ingurumeneko uretan kutsatzaile organiko desberdinak aurkitzen dira nahiz eta kontzentrazio baxuetan izan (ng/L mailan). Araztegien irteera korronteak izan ohi dira konposatu horien iturririk nagusienetako bat, araztegiek erabiltzen dituzten mekanismoak ez baitira gai kutsatzaileen arazketa osoa burutzeko. Horien artean, konposatu disruptore (EDC)...
Article
The characterization of ancient lipids from prehistoric organic residues (fumiers) located in rock-shelters has been possible after the optimization of an analytical method based on the microwave-assisted extraction and solid-phase extraction clean-up step and a final derivatization step followed by gas chromatography with mass spectrometry. Eight...
Article
The uptake calibration of three passive samplers, stir-bars, MESCO/stir-bars and polyethersulfone tubes (PESt), was assessed in seawater at different salinities for 17 organic compounds including organochlorine compounds, pesticides, phthalates, musk fragrances and triclosan. The calibration procedure was accomplished by exposing the samplers to a...
Article
This study describes a new method for the simultaneous extraction of several endocrine disrupting compounds, including alkylphenols (APs), estrogen, bisphenol-A (BPA) and one phthalate metabolite (mono-2-ethylhexyl ester, MEHP) in fish liver, brain, and muscle. Parameters affecting the extraction (extraction solvent and temperature) and the clean-u...
Article
The uptake calibration of more than 12 non-polar organic contaminants by 3 polymeric materials is shown: bare polydimetilsiloxane (PDMS, stir-bars), polyethersulfone tubes and membranes (PES) and polyoxymethylene membranes (POM), both in their free form and membrane-enclosed sorptive coating (MESCO). The calibration process was carried out exposing...
Article
Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and multiple headspace extraction-gas chromatography-mass spectrometry (MHSE), respectively. The monoterpenes were 1st extrac...
Article
Dispersive liquid-liquid microextraction (DLLME) is a recent microextraction technique that was first developed by Rezaee and co-workers in 2006. It allows the simultaneous extraction and preconcentration of analytes into a micro-volume of extracting solvent based on a ternary solvent system involving an aqueous phase, a nonpolar water immiscible h...
Article
Full-text available
Laburpena: Lan honetan, optimizatu egin da bi urratseko jariakin gainkritikoaren bi-dezko erauzketa (SFE Supercritical Fluid Extraction), ardo hondakinetatik konposatu bioaktiboak lortzeko. Ondorioz, lortu da lehen urratsean gantz azidoak soilik eta biga-rren urratsean polifenolak soilik erauztea. Polifenolek egonkortasun eskasa dute ordea. Hori de...
Article
Full-text available
This study describes a new method for the simultaneous extraction and enzymatic hydrolysis of alkylphenols, estrogens, bisphenol-A and phthalate metabolite (mono-2-ethylhexyl ester, MEHP) in fish bile using polyethersulfone (PES) polymer as sorptive material. Parameters affecting the hydrolysis (enzyme amount) and extraction (nature of polymeric ma...
Article
This work describes a new methodology for the simultaneous determination of a large variety of emerging and persistent organic compounds and some of their metabolites in fish bile samples. The target compounds were musk fragrances, alkyl phenols, hormones, pesticides, phthalate esters and bisphenol-A, all of them with a known endocrine disrupting e...
Article
The interest in the analysis of alkylphenols (APs) has widely increased in the last decades because of the endocrine disrupting features of these phenol derivatives. However, the isolation and identification of many of the multiple chemical structures of all APs is a very challenging task because of their similar physicochemical properties. In this...
Article
Full-text available
In this study, supercritical fluid extraction has been successfully applied to a sequential fractionation of fatty acids and polyphenols from wine wastes (2 different vitis vinifera grapes). To this aim, in a 1st step just fatty acids were extracted and in a 2nd one the polyphenols. The variables that affected to the extraction efficiency were sepa...
Article
Full-text available
Biomonitoring programs are essential tools to evaluate the biological quality status of aquatic environments. Recently, several compounds with endocrine disruption ability have been included in the list of priority substances and therefore, implementation of biomarkers assessing the presence and the effects of such substances are required. In the p...
Article
Focused-ultrasound solid–liquid extraction was developed for the extraction of polybrominated diphenyl ethers in vegetables and amended soil. Firstly, solid-phase extraction clean-up using 2 g and 5 g of Florisil and 2-g silica cartridges were evaluated and elution profile was also optimised. Similar recoveries were obtained for most compounds whil...
Article
Among the different organic pollutants, persistent organic pollutants and emerging organic contaminants (EOCs) are of particular concern due to their potentially dangerous effects on the ecosystems and on human health. In the framework of the analysis of some of these organic pollutants in water samples, sorptive extraction devices have proven to b...
Chapter
Full-text available
Monoterpenes and sesquiterpenes are naturally occurring organic products derived from two and three assembled isoprene units (C10H16 and C15H24), respectively. These compounds are very abundant in plants and due to their aromatic qualities have been employed for centuries as odorants for the house and body, flavorful plates and in homemade cosmetic...
Article
Endocrine disrupting chemicals (EDCs) interfere with the functioning of the endocrine system, causing reproductive and developmental disturbances in aquatic wildlife. Appearance of intersex gonads and elevated plasma levels of vitellogenin in male fish are well known biomarkers of exposure to xenoestrogenic EDCs. In the present study, intersex cond...
Conference Paper
Chemical compounds known as endocrine disruptors (EDs) may alter the functions of the endocrine system and consequently cause adverse health effects to an organism, its progeny or (sub)populations. Recently thicklip grey mullets (Chelon labrosus) inhabiting different estuaries of the Basque Country have been found to show signs of endocrine disrupt...
Article
Derivatization is necessary when analysis of polar compounds containing hydroxyl, carboxylic acid, amine or thiol functional groups is accomplished by gas chromatography (GC), in order to improve peak symmetry, peak separation and detector response. Derivatization can be performed off-line in a reaction vessel that is separated from the GC analysis...
Article
In this work, home-made Polar Organic Chemical Integrative Samplers (POCIS) were studied for passive sampling of 15 endocrine disrupting compounds (4 alkylphenols and steroid hormones) in influent and effluent samples of wastewater treatment plants (WWTPs) as well as up- and downstream of the receiving river water. POCIS calibration at laboratory c...
Article
Priority pollutants constitute only a part of the large chemical pollution puzzle where the number of potentially hazardous chemicals that reaches the environment is very wide and new substances are constantly being developed and released. Among them, a diverse group of unregulated pollutants, many times called "emerging" contaminants, including ph...
Article
In the present work the simultaneous extraction for the multiresidue determination in wastewater samples of organic compounds such as polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), pesticides, polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PEs), alkylphenols (APs), bisphenol A (BPA) or hormones included in different...
Article
Full-text available
Gas chromatography is a widely used technique in research in order to indentify, determine and quantify volatile and semi-volatile compounds. However, the limitations of this technique make impossible the identification and quantification of many of them. Nowadays, and in order to overcome these limitations, multidimensional gas chromatography has...
Article
This work describes the optimisation, validation and application of membrane assisted solvent extraction (MASE) together with a large volume injection (LVI) in a programmable temperature vaporisation (PTV) injector coupled to gas chromatography-mass spectrometry (GC-MS) for the quantification of ten synthetic musk fragrances (musks) in surface and...
Article
Comprehensive two-dimensional gas-chromatography (GC×GC) is a great tool to explore complex essential oils. In this work the different terpene composition of the aroma fraction of rosemary and oregano were studied. The present investigation is based on the optimization of the comprehensive two-dimensional gas-chromatographic method through the use...
Article
A fully automated protocol consisting of microextraction by packed sorbents (MEPS) coupled with large volume injection-in-port-derivatization-gas chromatography-mass spectrometry (LVI-derivatization-GC-MS) was developed to determine endocrine disrupting compounds (EDCs) such as alkylphenols, bisphenol A, and natural and synthetic hormons in river a...
Article
In the present work, the separation of complex nonylphenol technical mixtures has been optimized using comprehensive two-dimensional gas chromatography coupled with a flame ionization detector and quadrupole mass spectrometer (GC×GC-qMS), using valve-based modulator. The optimization of GC×GC-qMS has been carried out using experimental designs and...
Article
Large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry (LVI-PTV-GC-MS) was optimized for the determination of estrone (E1), 17β-estradiol (E2), 17α-ethynyl estradiol (EE2), mestranol (MeEE2) and estriol (E3) for their determination in environmental samples (estuarine water, wastewater, fish bile and fish h...
Article
The analysis of hydrocarbons in chert rocks provides a worthwhile source of information regarding the geochemical features of a depositional setting. Since the typical analytical procedure requires long Soxhlet extractions and the use of large quantities of sample (30-50 g), in this work we have optimised the focused ultrasound extraction (FUSE) an...
Article
Full-text available
According to the European Water Framework Directive (WFD), alkylphenols, such as octylphenols and nonylphenols, and 17β-oestradiol are considered as priority or emerging pollutants, respectively, mainly due to their possible properties as endocrine-disrupting compounds (EDCs). EDCs are accumulated in liver, fat, kidney and bile in the glucuronide f...
Article
The analysis of organic biomarkers in chert samples offers key information about the environmental conditions in which these samples were formed, and this information can be used to track the lithic materials of many archaeological artifacts. Since the content of the organic fraction is very low and the complexity of the organic extracts is quite h...
Article
The determination of target analytes such as nonyl- and octylphenols and 17beta-estradiol in fish homogenate require of solid-liquid extraction step. In this work microwave-assisted extraction (MAE) and focused-ultrasound liquid extraction (FUSLE) were studied as two different alternatives for extraction of the target compounds in zebrafish (Danio...
Article
Cup horn boosters are miniaturized ultrasound baths that maximize efficiency and precision. The optimization of an ultrasonic-assisted derivatization step by means of a cup horn booster and the determination of estrone, 17beta-estradiol, estriol, 17alpha-ethynyl estradiol and mestranol was developed by GC-MS. Different derivatization reagents and s...
Article
In this work the simultaneous purge-and-trap (P&T) preconcentration of volatile fatty acids (acetic acid, propanoic acid, butanoic acid, iso-butanoic acid, pentanoic acid, iso-pentanoic acid, hexanoic acid and heptanoic acid), phenols (phenol, 4-methylphenol and 4-ethylphenol) and indoles (indole and 3-methylindole) from cow slurries was carried ou...
Article
Odorous organic compounds from liquid and gas samples of animal wastes were studied by headspace (HS)-solid-phase microextraction (SPME)-GC-MS. 1-Pirenyldiazomethane (PDAM) was adsorbed/absorbed on the SPME fibre in order to obtain the corresponding ester derivatives during the preconcentration step. The SPME fibre was immersed into a PDAM solution...
Article
The headspace solid-phase microextraction (HS-SPME) of some odorous organic compounds [volatile fatty acids (VFAs), phenols and indoles] from animal wastes was optimised using an experimental design approach. The variables affecting the HS-SPME process studied were as follows: type of fibre, pH of the slurry (3-7), addition of sodium chloride (0-1...

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