35 research outputs found
Aplicación de la cromatografía líquida acoplada a la espectrometría de masas para la evaluación de la exposición interna a contaminantes alimentarios
No full textLa contaminación química es actualmente un grave problema de salud pública. La producción de sustancias químicas aumenta a un ritmo vertiginoso, y aunque los países desarrollados (OECD) producen la mayoría de las mismas, el crecimiento en países como Brasil, India, Indonesia, China o Sudáfrica (BRIICS) se produce con mayor velocidad.
Un porcentaje elevado de estas sustancias son potencialmente peligrosas para la salud, y el ser humano está expuesto a las mismas principalmente mediante ingestión, inhalación o por vía dérmica. Consecuentemente, es importante para la protección de la salud estudiar el grado de exposición de la población a las distintas sustancias químicas, ya sea mediante la monitorización ambiental, estudiando la presencia de contaminantes en los diferentes compartimentos ambientales (agua, alimentos, aire, suelo, etc…), o mediante la biomonitorización humana, determinando los niveles de biomarcadores de exposición en matrices biológicas (sangre, orina, leche materna, etc…). La biomonitorización humana nos proporciona datos sobre la exposición interna por lo que integra todas las vías de exposición. La presente tesis doctoral está centrada en el estudio de la biomoniotorización humana de contaminantes alimentarios mediante el desarrollo de metodologías analíticas basadas en cromatografía líquida acoplada a espectrometría de masas y la aplicación de las mismas en estudios poblacionales para conocer la exposición de la población y llevar a cabo la evaluación del riesgo.
La tesis está conformada por seis capítulos, que se corresponden con los artículos científicos que la sustentan. En general, se pueden agrupar en artículos de desarrollo de metodología analítica (capítulos 1, 2 y 3) y en artículos de niveles poblacionales (exposición) y de evaluación del riesgo (capítulos 4, 5 y 6).
Los capítulos 1 y 2 se centran en el análisis de muestras de orina para la determinación de plaguicidas mediante cromatografía líquida acoplada a espectrometría de masas de alta resolución. El primero está más enfocado a la identificación de nuevos metabolitos en orina, mientras que el segundo se centra en la optimización de un método analítico de cuantificación.
En el capítulo 3 se describe el desarrollo de una metodología analítica multiresiduo para la determinación de bisfenoles y parabenos en leche materna mediante cromatografía líquida acoplada a espectrometría de masas con analizador de triple cuadrupolo. La metodología desarrollada se empleó posteriormente en los capítulos 4 y 5 para determinar los niveles poblacionales de bisfenoles y parabenos, respectivamente, en madres lactantes y llevar a cabo la evaluación del riesgo para sus hijos.
Por último, en el capítulo 6 se determinan metabolitos de ftalatos en orina en madres lactantes y se lleva a cabo la correspondiente evaluación del riesgo.
Con respecto a los resultados, en el capítulo 1 se llevó a cabo con éxito un análisis retrospectivo mediante diferentes enfoques: análisis de sospechosos, análisis de desconocidos y análisis multivariante en diferentes poblaciones. El estudio permitió la identificación y confirmación de seis metabolitos de plaguicidas mediante búsqueda de sospechosos, la identificación de un metabolito mediante búsqueda de desconocidos, así como la diferenciación mediante análisis de componentes principales de las diferentes poblaciones estudiadas.
En el capítulo 2 se optimizaron los parametros espectroméricos de un método de cromatografía líquida acoplada a espectrometría de masas de alta resolución tipo Orbitrap. Como resultado, el poder de resolución (25.000 FWHM), el tipo de fragmentación (CID 40 eV) y el tipo de calibración de masas (cafeína como calibrante interno para ESI positivo), demostraron mejorar las prestaciones del análisis en términos de sensibilidad y exactitud.
En el capítulo 3, la utilización de la extracción mediante QuEChERS combinada con la determinación mediante espectrometría de masas en tándem y aplicando ionización en modo negativo, permitió el desarrollo de un método optimizado y validado para la determinación de tres bisfenoles y cuatro parabenos en leche materna con límites de cuantificación (LoQ) de entre 0,1 y 0,25 ng/mL.
En los capítulos 4 y 5 el bisfenol A y los parabenos se detectaron en más del 60% de las muestras analizadas, mientras que los bisfenoles F y S presentaron frecuencias de detección reducidas (<25%). Las concentraciones de bisfenoles y parabenos en leche se encontraron en un rango de entre <LoQ y 49 ng/mL. El estudio de evaluación del riesgo para bisfenol A y parabenos en recién nacidos lactantes concluyó que las ingestas diarias estimadas de estos compuestos a través de la lactancia no se consideran un riesgo para la salud de la población estudiada.
En el capítulo 6, nueve de los metabolitos de ftalatos estudiados se detectaron en más de un 80% de las muestras, mientras que los niveles de metabolitos oscilaron entre <LoQ y 1291 ng/mL. Los estudios de evaluación del riesgo determinaron que la exposición a ftalatos en la población de madres estudiada no superaba los valores límite y, por tanto, no se considera que hubiera un riesgo para su salud.
La cromatografía líquida acoplada a espectrometría de masas permite la determinación de biomarcadores de contaminantes alimentarios en los niveles presentes en las muestras biológicas. La combinación del uso de técnicas de cuantificación ‘target’ así como otros enfoques como la búsqueda de sospechosos o de desconocidos permite conocer el grado de exposición de la población a contaminantes y llevar a cabo estudios de evaluación del riesgo. En general, se observa que la presencia de contaminantes alimentarios fue elevada en las muestras biológicas analizadas, sin embargo, los niveles detectados no se consideran peligrosos para las poblaciones estudiadas.Chemical pollution is currently a paramount public health concern. Chemical production has spread rapidly and despite its production is mainly focused in OECD nations, in countries as Brazil, India, Indonesia, China or South Africa (BRIICS) the production is growing rapidly. A high ratio of these compounds are considered potentially life-threatening and human beings are exposed to them through ingestion, inhalation and dermal exposure mainly. Consequently, in order to ensure health safety, the exposure of population to chemicals must be assessed through environmental monitoring, studying the presence of contaminants in environmental compartments (water, food, air, soil, etc…), or through human biomonitoring, assessing the levels of exposure biomarkers in biological matrices (blood, urine, human milk, etc…), which informs about the internal exposure and integrates all the routes of exposure. The present doctoral thesis is focused in the study of human biomonitoring of food contaminants through the development of analytical methodologies fundamented on liquid chromatography coupled to mass spectrometry in order to assesss the exposure of the populantion and implement the risk assessment.
The thesis is composed of six chapters, which correspond with six scientific papers. In general they can be grouped as analitcal method development papers (chapters 1, 2 and 3) and papers focused on exposure and risk assessment (chapters 4, 5 and 6).
Chapters 1 and 2 are focused on the determination of pesticide biomarkers in urine samples through liquid chromatography coupled to high resolution mass spectrometry. In the first chapter the objective is the identification of new metaoblites in urine, while the second is focused in the optimization of a quantification analytical method.
In chapter 3 the development of a multiresidue analytical methodology for the determination of bisphenols and phthalates in human milk is described. The method is based on liquid chromatography coupled to triple quadrupole mass spectrometry. This method is applied in chapters 4 and 5 for the determination of levels of bisphenols and parabens, respectively, in lactating mothers and the implementation of a risk assessment study in breastfed newborns.
Finally, in chapter 6 urinary phthalate metabolites are determined in urine of lactating mothers and a risk asssessment study is implemented.
Regarding results, in chapter 1 a retrospective analysis was implemented through different approaches: suspect screening, unkonwn analysis and multivariant analysis of different populations. The study allowed the identification and confirmation of six pesticide metabolites through suspect screening, the identification of one metabolite through unknonwn analysis, and the separation of the different studied populations through principal component analysis.
In chapter 2, the spectrometric parameters of a method of liquid chromatography coupled to an Orpitrap high resolution mass spectrometer were optimized. As a result, the resolving power (25,000 FWHM), the fragmentation (CID 40 eV) and the mass calibration in ESI positive with caffeine as lock mass were selected in order to improve the analytical performance in terms of sensitivity and accuracy.
In chapter 3, QhEChERS extraction combined with the determination using tandem mass spectrometry and negative ionization allowed the development of an analytical method for the determination of three bisphenols and four parabens in human milk with limits of quantification (LoQ) ranging from 0.1 to 0.25 ng/mL.
In chapter 4 and 5, bisphenol A and parabens were detected in more than 60% of the samples, while the bisphenols F and S showed reduced detection frequencies (<25%). The concentrations of bisphenols and parabens in human milk ranged from <LoQ and 49 ng/mL. The risk assessment study for bisphenol A and parabens concluded that the estimated daily intakes of these compounds through breasfeeding in newborns were not considered dangerous for the studied population.
In chapter 6, nine phthalate metabolites were detected in more than 80% of samples and the concentrations ranged from <LoQ to 1291 ng/mL. The risk assessment studies determined that the phthalate exposure of the mother population studied did not exceeded the threshold values and, therefore, a health risk derived from the exposure to phthalates was discarded.
Liquid chromatography coupled to mass spectrometry allows the determination of food contaminant biomarkers at concentrations usually present in biological matrices. The use of quantification approaches (target) combined with other approaches such as suspect screening or unkonwn analysis allows to study the exposure of the population to contaminants and to implement risk assessment studies. In general, the presence of food contaminants was elevated in the samples analyzed, however, the levels detected were not considered dangerous for the populations studied
Liquid chromatography‐Orbitrap Tribrid high‐resolution mass spectrometry using data dependent‐tandem mass spectrometry with triple stage fragmentation as a screening tool to perform identification and risk assessment of unknown substances in food contact epoxy resin
No full textStudent Assessment of Oral Presentations in German as a Foreign Language
No full textAbstractStudents are usually afraid of making oral presentations in a foreign language, mainly when they are beginners, as it is the case in this work. The main idea was to study how language skills were evolving and if students were able to recognize that progress. This work presents the methodology that has been followed in order to integrate the students’ assessment in the evaluation of their oral presentations in German as a Foreign Language, at the Universitat Politècnica de València. The testing process was carried out in two ways: peer and self-assessment. Data was collected according to the various presentations. The paper describes the quantitative results of peer evaluation throughout the term and the qualitative feedback they provided. Data analysis permitted to observe how peer and self-assessment positively evolved throughout the term. What can be considered more important is that students have improved their formal communication skills, while they have also developed their knowledge on German language
Sensitivity of two methods to detect Mycoplasma agalactiae in goat milk
No full text© 2015 Tatay-Dualde et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background: Laboratory diagnostic techniques able to detect Mycoplasma agalactiae are essential in contagious
agalactia in dairy goats. This study was designed: 1) to determine the detection limits of PCR and culture in goat
milk samples, 2) to examine the effects of experimental conditions including the DNA extraction method, PCR
technique and storage conditions (fresh versus frozen stored milk samples) on these methods and 3), to establish
agreement between PCR and culture techniques using milk samples from goats with mastitis in commercial dairy
herds. The study was conducted both on artificially inoculated and field samples.
Results: Our findings indicate that culture is able to detect M. agalactiae in goat milk at lower concentrations than
PCR. Qualitative detection of M.agalactiae by culture and PCR was not affected by sample freezing, though the
DNA extraction method used significantly affected the results of the different PCR protocols. When clinical samples
were used, both techniques showed good agreement.
Conclusions: The results from this study indicate that both culture and PCR are able to detect M. agalactiae in clinical
goat mastitis samples. However, in bulk tank milk samples with presumably lower M. agalactiae concentrations, culture
is recommended within the first 24 h of sample collection due to its lower limit of detection. To improve the diagnostic
sensitivity of PCR in milk samples, there is a need to increase the efficiency of extracting DNA from milk samples using
protocols including a previous step of enzymatic digestion
Untargeted analysis and tentative identification of unknown substances in human tears by ultra-high performance liquid chromatography-high resolution mass spectrometry: Pilot study
No full textIn this work, a new approach for the identification of unknown compounds in human tears has been developed and validated using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) linked to an intelligent data acquisition mode (AcquireX DS-dd-MS2) coupled to an automated data processing software (Compound Discoverer™ 3.2). As a pilot research study, four human tear samples from volunteers were analyzed. Data were acquired in both positive and negative ionization modes and exact mass, isotope pattern, and MS2 spectra match were used for the tentative identification. Following this approach, 58 substances were identified, 47 in positive mode and 11 in negative mode, with an estimated concentration ranging from 0.1 to 9000 ng mL-1. Most of them were amino acids, hormones, metabolites, and pharmaceuticals. In order to validate the proposed method, the system suitability was evaluated and 29 commercial analytical standards of the tentatively identified substances were analyzed, of which 28 were confirmed obtaining a high identification accuracy (96.6 %). These results confirm that the screening tool presented in this work can facilitate the discovery of new metabolites, novel potential biomarkers, and substances to which the person is exposed, such as pollutants.Medicin
Urinary Biomonitoring of Mycotoxins in Spanish Adults: Predictors of Exposure and Health Risk Evaluation
No full textMycotoxins are toxic secondary metabolites produced by fungi, frequently present in food and representing significant health hazards. Exposure occurs through the consumption of contaminated foods or animal-derived products from livestock fed with contaminated feed. This study evaluated internal exposure to twelve mycotoxins in 492 first-morning urine samples from adults, aged 18–65 years, in the Valencian Community, Spain. Samples were analysed using a “dilute-and-shoot” approach followed by UHPLC-MS/MS. Aflatoxins (AFs) were the most frequently detected, with a geometric mean (GM) of 1.17 ng/mL and a 95th percentile (P95) of 6.04 ng/mL. Alternariol (AOH), present in 63% of samples, showed high concentrations (GM: 0.98 ng/mL; P95: 4.74 ng/mL). Emerging mycotoxins such as alternariol monomethyl ether (AME), citrinin (CIT), and sterigmatocystin (STER) were also considered due to their potential health impacts. Exposure levels correlated with variables including sex, age, annual income, smoking status, and recent consumption of meat and cereals. Probable daily intakes (PDIs) were estimated from urinary concentrations to support risk assessment. Hazard Quotients (HQs), Margins of Exposure (MOEs), the Hazard Index (HI) and the total Margin of Exposure (MOET) were calculated to evaluate the risk associated with mycotoxin exposure. Findings suggest that potential health risks cannot be excluded
Optimization of Resolving Power, Fragmentation, and Mass Calibration in an Orbitrap Spectrometer for Analysis of 24 Pesticide Metabolites in Urine
No full textMass spectrometer parameters such as Resolving Power, type of fragmentation, and mass calibration mode were optimized in the analysis of 24 pesticide metabolites in human urine using Ultra-High Pressure Liquid Chromatography coupled to Orbitrap High-Resolution Mass Spectrometer (UHPLC-HRMS). The best results were achieved with a Resolving Power of 25,000 FWHM and by applying Collision Induced Dissociation fragmentation mode (40 eV)
Identification of 24 Unknown Substances (NIAS/IAS) from Food Contact Polycarbonate by LC-Orbitrap Tribrid HRMS-DDMS3: Safety Assessment
No full textTwenty-four substances, mainly NIAS, have been tentatively identified in food contact polycarbonate through the application a new, fast, and automated analytical strategy for the investigation of unknowns in food contact materials. Most of the identified compounds were plasticizers, slip agents, antioxidants, and ultraviolet stabilizers and fragrances, and the majority of them have not been previously identified in PC food contact materials. The workflow setup includes an intelligent data acquisition applied using LC-Orbitrap Tribrid-HRMS (MS3), with an automated data processing using Compound DiscovererTM. To obtain a high confidence identification of unknown substances, a very strict criterion has been established, which comprises exact mass, isotopic profile, MS2 match, retention time, and MS3 match. To check for the safety of the migration from the food contact polycarbonate, a risk assessment was achieved using the threshold of the toxicological concern (TTC) approach. Except for the slip agent hexadecanamide, the compounds tentatively identified do not represent a risk
Identification of 24 unknown substances (NIAS/IAS) fro Food Contact Polycarbonate by LC-Orbitrap Tribrid HRMS-DDMS3 Safety Assessment
No full textTwenty-four substances, mainly NIAS, have been tentatively identified in food contact polycarbonate through the application a new, fast, and automated analytical strategy for the investigation of unknowns in food contact materials. Most of the identified compounds were plasticizers, slip agents, antioxidants, and ultraviolet stabilizers and fragrances, and the majority of them have not been previously identified in PC food contact materials. The workflow setup includes an intelligent data acquisition applied 3 TM using LC-Orbitrap Tribrid-HRMS (MS ), with an automated data processing using Compound Discoverer . To obtain a high confidence identification of unknown substances, a very strict criterion has been established, which comprises exact mass, isotopic profile, MS2 match, retention time, and MS3 match. To check for the safety of the migration from the food contact polycarbonate, a risk assessment was achieved using the threshold of the toxicological concern (TTC) approach. Except for the slip agent hexadecanamide, the compounds tentatively identified do not represent a risk
Biomonitoring of glyphosate and AMPA in the urine of Spanish lactating mothers
No full textThe objectives of this study were to evaluate the urinary levels of Glyphosate (Gly) and its metabolite aminomethylphosphonic acid (AMPA) in Spanish breastfeeding mothers (n= 97), to identify the main predictors of exposure and to perform a risk assessment. Urine samples were analyzed using a method based on solid phase extraction and liquid chromatography tandem mass spectrometry (LC-MS/MS) determination. The developed method showed limits of quantification of 0.1 μg/L for both analytes. The detection frequencies (DFs) were 54% for Gly and 60% for AMPA, with geometric means (GMs) of 0.12 μg/L and 0.14 μg/L, respectively. In the statistical analysis, no relationship was found between the urinary levels of Gly and AMPA. Multiple regression analysis showed a significant relationship between the intake of eggs and fruits and Gly levels in urine. Estimated daily intakes (EDIs), hazard quotients (HQs), and a hazard index (HI) were calculated to analyze the obtained data from a health risk perspective. The GMs of the EDIs were 0.31 and 0.37 μg/kg of body weight (BW)/day for Gly and AMPA, respectively. The HQs were calculated considering 0.5 mg/kg BW/day as an acceptable daily intake (ADI), which EFSA has established as a health-based reference value for both analytes. The values obtained were lower than 1, and thus, low health risk due to Gly and AMPA exposure was expected for the population under study
