87 research outputs found
Bisphenols determination in seminal fluid by miniaturized stir bar sorptive dispersive microextraction as a potential tool in male infertility studies
No full textIn this work, an analytical method for the determination of bisphenols in seminal fluid is presented. These compounds are related to the deterioration in sperm quality due to their highly endocrine disruptive activity. The method is based on miniaturized stir bar sorptive dispersive microextraction (mSBSDME), and the extract is analyzed by liquid chromatography coupled to tandem mass spectrometry. Prior to the extraction, precipitation of the proteins from the sample was conducted with acetonitrile and, subsequently, the supernatant was evaporated and reconstituted in water. Next, a hydrophilic-lipophilic polymer-coated magnetic nanoparticles composite was used as magnetic sorbent in mSBSDME. The ratio of magnetic nanoparticles and polymer used for the synthesis of the sorbent was firstly optimized. A Plackett-Burman design was employed for the evaluation of the critical variables involved in the microextraction step, which were then optimized employing response surface methodologies. Under the optimized conditions, the proposed method was validated, obtaining satisfactory linearity (up to 50 ng mL−1), enrichment factors (6.3–13.6), limits of detection in the low ng mL−1 range, and precision (relative standard deviation below 12 %). Finally, the method was successfully applied to seminal fluid samples from eight volunteers, detecting bisphenol A (BPA) and bisphenol S (BPS) in most of them. This methodology not only broadens the analytical potential of mSBSDME for other complex and low-volume matrices but also contributes to the monitorization of the population exposure to bisphenols and would allow determining its relationship with male reproductive effects in subsequent clinical studies.Grants PID2020-118924RB-I00 and PID2021-122327OB-I00 funded by Spanish Ministry of Science and Innovation (MICIU/AEI/10.13039/501100011033) and by “ERDF A way of making Europe” are greatly appreciated. A.L.L-J also thanks the Generalitat Valencia for the INVESTIGO contract through the project INVEST/2022/109. This article is based upon work from the National Network for Sustainable Sample Preparation (RED2022-134079-T funded by MICIU/AEI/ 10.13039/501100011033) and the Sample Preparation Study Group and Network supported by the Division of Analytical Chemistry of the European Chemical Society.Peer reviewe
Desarrollo de métodos analíticos para el control de filtros UV de naturaleza orgánica en productos cosméticos para la protección solar.
No full textRESUMEN
El actual deterioro de la capa de ozono ha provocado un incremento de la radiación
UV solar que llega a la Tierra, que hace necesaria una mayor protección con el fin de
evitar efectos perjudiciales para la salud. El uso de productos cosméticos para la
protección solar que incorporan filtros UV en su formulación podría contribuir a
prevenir estos efectos dañinos.
El control analítico de estos productos es necesario, ya que debe garantizarse su
eficacia y seguridad. Sin embargo no existen métodos oficiales para su análisis, por lo
que el desarrollo de métodos analíticos rápidos y exactos para el control del producto
cosmético acabado es de gran interés, y constituye el objeto de esta Tesis Doctoral.
Se ha puesto especial atención en el desarrollo de métodos en los que se utilicen
reactivos inocuos o de baja toxicidad, reduciendo igualmente la cantidad de reactivos
utilizada y minimizando la generación de residuos, con el fin de proponer métodos de
análisis limpios, y así cumplir con la actual tendencia de la química analítica
denominada Química Analítica Verde (Green Analytical Chemistry, en inglés).
Se han propuesto métodos automatizados basados en el uso de la espectroscopía de
absorción UV/VIS, fluorimetría y quimioluminimetría. La automatización de los
procedimientos permite aumentar la rapidez del análisis. Las características analíticas
de estos métodos son adecuadas para el control analítico de los filtros UV en los
productos cosméticos acabados.
También se han desarrollado métodos de cromatografía líquida con detección UV/VIS
que permiten realizar en pocos minutos la determinación simultánea de los filtros UV
más utilizados a nivel internacional. Las características analíticas de estos métodos
son adecuadas para el control analítico de los productos cosméticos acabados.
Además, en el último capítulo de esta Tesis Doctoral, se ha puesto a punto un método
analítico para la determinación en orina de usuarios de productos cosméticos para la
protección solar de uno de los filtros UV más utilizados, con el fin de estudiar los
mecanismos de excreción y acumulación en el organismo y facilitar información sobre
su posible efecto toxicológico.
__________________________________________________________________________________________________Damage to the ozone layer has led to an increment in the solar UV radiation reaching
earth, which in turn makes strong protection necessary in order to prevent harmful
effects on human health. The use of sunscreen cosmetics could help to prevent or
minimize these harmful effects.
The analytical control of these products is necessary, since their efficacy and safety
must be guaranteed. However, there are no official analytical methods to be used, and
thus the development of rapid and accurate analytical methods in order to control
sunscreen cosmetics is, without any doubt, of high interest, and this topic is the aim of
this Doctoral Thesis. Special attention has been paid in the development of methods
that use harmless reagents or with low toxicity, and moreover, by reducing the amount
of employed reagents and thus minimizing the volume of waste of products generated,
by proposing friendly (or green) analytical methods for both the environment and
operator in order to fulfil with the current tendency of the analytical chemistry known as
Green Analytical Chemistry.
In this sense, different automated methods based on the use of UV/VIS absorption
spectroscopy, fluorimetry and chemiluminiscence have been proposed. The
automation of the procedures allows increasing the sample throughput. The analytical
features of these methods are very suitable for the analytical control of the UV filters in
the sunscreen cosmetic products.
On the other hand, different methods based on the use of liquid chromatography with
UV/VIS detection have been also proposed, which allow the simultaneous
determination of the worldwide most used UV filters in few minutes. The analytical
features of these methods are also very suitable for monitoring the UV filters in the
cosmetic products.
Finally, the last chapter of this Doctoral Thesis is focused on the development of an
analytical method able to determine one of the most used UV filter in urine samples
coming from users of sunscreen cosmetic products, in order to study the excretion and
bioaccumulation mechanisms in the human body, and thus providing information on its
possible toxicological side-effects
Impact of RPAS operations on the ATM Network: Minimum performance and operational requirements for the en-route phase
No full textThe popularity of Remotely Piloted Aircraft Systems (RPAS) is growing at an increasing rate as an alternative to manned aviation for different purposes and applications. So far, most of their operations have been of military character, but the demand for civil and commercial applications is growing exponentially. RPAS have been allowed to operate in segregated airspace by restricting other users from entering the volume associated to the operation of the RPAS. This temporary solution based on accommodating their operations on a case-by-case basis is not feasible on the long-term. Moreover, the latest forecast carried out by SESAR Joint Undertaking (SJU) reveals that by 2050 RPAS will represent 20% of the fleet. The available airspace is a scarce resource and is already saturated, which means that additional unmanned operations would not be possiblesimultaneously. Integration in non-segregated airspace is the only manner in which the full benefits and capabilities of RPAS will be achieved, while maintaining the same levels of safety and efficiency as manned aviation.In order to achieve a safe, efficient and transparent integration, a common regulatory framework and new technologies are currently under investigation. However, neither operational nor performance standards of RPAS integration have been addressed properly. For that reason, this project is focused on the development of a methodology to determine minimum operational and performance requirements by assessing the impact of RPAS operations on the Air Traffic Management (ATM) Network. The scope is limited to the en-route phase as a starting point since none of the flight phases have been analysed yet. This project is carried out in collaboration with EUROCONTROL. RPAS are well known for presenting a wide range of performance characteristics, especially in terms of cruise speed and rate of climb. Thus, two different unmanned performance models have been chosen from the available performance models in the EUROCONTROL database: RP01 (MQ-9), which presents a similar performance to commercial aviation aircraft, and RP02 (RQ4A), which is considered a low-performanceRPAS in terms of cruise speed and rate of climb. Building on a base scenario in the Paris Control Terminal Area (CTA),Monte Carlo simulations of the air traffic have been performed in order to randomly vary the main input variable: the set of en-route flights that is substituted by unmanned aircraft. Two different scenarios have been analysed separately in order to establish the requirements: one for same-performance RPAS, and theother for low-performance RPAS. In order to assess the impact, three different Key Performance Areas (KPAs) have been selected: capacity, efficiency and safety. These KPAs are in turn characterized by their corresponding Key Performance Indicators (KPIs), namely sector capacity, sector overload, flight time efficiency, flight path efficiency and number of potential conflicts.Based on an analysis of the current occupancy of the flight levels, operational requirements are defined in terms of altitude segregation. RPAS are not allowed to operate in the most occupied flight levels (FL): from FL300 to FL400. Therefore, depending on their operation and performance characteristics (i.e. ceiling), they will adapt their cruise FL to operate below FL300 or above FL400. The optimal value of performance requirements for same-performance RPAS has been found to be a minimum cruise speed of 390 kts, while for low-performance RPAS this minimum cruise speed is of 280 kts. Additionally, for low-performance RPAS, it is found that the rate of climb of 1,000 fpm results in the best performing case when changes in FL are required.The results show that the values of the key performance indicators for the base scenario are difficult to reach when RPAS are sharing the airspace. However, the establishment of minimum operational and performance requirements contributes to a significant reduction of the negative impact that the integration of RPAS operations implies.The development of this methodology and its application to the characteristics of each airspace sector will contribute to the full integration of RPAS in non-segregated airspace.Aerospace Engineerin
Analysis of cosmetic products /
No full textThe first book in 20 years to be dedicated to Cosmetic Analysis.Includes index.Print version record.Front Cover; Analysis of Cosmetic Products; Copyright page; Contents; Preface; Foreword; Acknowledgements; List of Contributors; Part One: General Concepts and Cosmetic Legislation; Chapter 1. General Concepts and Cosmetic Legislation; Part Two: Main Ingredients in Cosmetics. Analytical Methods for Monitoring and Quality Control; Chapter 2. General Overview on Analytical Methods for Cosmetic Ingredients; Chapter 3. UV Filters in Sunscreens and other Cosmetics. Tanning and Whitening Agents. Analytical Methods; Chapter 4. Colouring Agents in Decorative and other Cosmetics. Analytical Methods.The first book in 20 years to be dedicated to Cosmetic Analysis.Includes bibliographical references and index.Elsevie
Analytical Methodologies for the Determination of Personal Care Products in Water Samples
No full textDesarrollo de métodos analíticos para la determinación de filtros UV: de los productos cosméticos al cuerpo humano y al medio ambiente
No full textLa presente Tesis Doctoral forma parte del Proyecto de Investigación CTQ 2009-12709 titulado “Desarrollo de métodos analíticos para la detección y cuantificación de trazas: de los productos cosméticos al cuerpo humano”.
Todos los estudios realizados están relacionados con un grupo de ingredientes cosméticos denominados “filtros UV”, de gran interés desde el punto de vista de la salud por el importante papel que ejercen en la protección de los usuarios frente a la radiación solar.
Se han desarrollado diversos métodos analíticos para la determinación de filtros UV con el fin de que puedan servir para contribuir a la realización de tres tipos de estudios que abarcan la cadena producto cosmético -> cuerpo humano -> medio ambiente:
1.- Control de calidad de la industria cosmética
Los filtros UV deben encontrarse en las concentraciones requeridas para asegurar el factor de protección solar del etiquetado y proteger así al usuario, sin sobrepasar los límites legales de concentración en el producto acabado establecidos en el Reglamento Europeo sobre productos cosméticos, por lo que se requiere el desarrollo y validación de métodos analíticos que garanticen su control.
2.- Estudios relacionados con la absorción/excreción en el cuerpo humano
Al aplicar el producto cosmético sobre la piel de los usuarios, los filtros UV son parcialmente absorbidos percutáneamente, posteriormente metabolizados en el cuerpo humano y finalmente excretados, por lo que se requieren métodos analíticos que permitan realizar este tipo de estudios en fluidos biológicos de los usuarios. Estos métodos son necesarios para sentar las bases científicas que apoyen las decisiones sobre la seguridad de los productos cosméticos que deben tomarse a nivel internacional y conllevarán el diseño y elaboración de formulaciones cosméticas cada vez más seguras para el usuario.
3.- Estudios medioambientales
Finalmente, indicar que también se requieren métodos analíticos para la determinación de los filtros UV en muestras medioambientales (tales como agua de mar y arena de playa) debido a que se trata de contaminantes emergentes. Los filtros UV llegan al medio ambiente por diferentes vías (principalmente por vía directa desde la piel de los usuarios).
Se ha potenciado a lo largo de toda la Tesis, para los tres tipos de muestras, el diseño, puesta a punto y validación de métodos analíticos novedosos y, en la medida de lo posible, se ha intentado desarrollar métodos analíticos que cumplan con las directrices de la denominada Química Verde
Miniaturization of sample preparation techniques as an essential strategy for the analysis of low-volume and complex samples
No full textSince their introduction in the 90s, microextraction techniques have evolved and adapted to the trends and needs of the moment. Nevertheless, much of the scientific focus has been on developing safer and more environmentally friendly extraction phases and/or reducing their quantities, with less emphasis on minimizing sample size. However, large volumes of biological samples are often not available and are really complex matrices with target compounds usually at trace level.
Thus, the objectives of this Doctoral Thesis, focused to overcome these new challenges in sample preparation, are:
-Exploiting the advantages offered by microextraction techniques for the determination of substances of interest in complex matrices.
-The miniaturization and adaptation of microextraction techniques for the simultaneous analysis of a large number of complex and low-volume samples.
The present Doctoral Thesis has been divided into three sections, containing a total of six chapters and the general conclusions.
SECTION 1 is constituted by Chapters 1 and 2. In Chapter 1, the concepts of miniaturization in Analytical Chemistry are briefly described and the most relevant microextraction techniques are described and classified. Next, in Chapter 2, an overview of the advances towards further miniaturization of the already miniaturized microextraction techniques, with special emphasis on those in which reduced sample volumes (generally < 1 mL) are used, is presented. This chapter does not provide an exhaustive revision of all the miniaturized applications, but a glimpse of the developments and trends in the field.
SECTION 2 is constituted by Chapters 3 to 6. These chapters are devoted to the presentation and discussion of the methodology and results obtained during the development of the analytical methodologies presented in this Doctoral
Thesis. In line with the general objectives, Chapter 3 makes use of stir bar sorptive dispersive microextraction (SBSDME) for the determination of trace amounts of tetrahydrocannabinol (psychoactive component of cannabis) in
cosmetic products containing ingredients derived from the hemp plant. In Chapters 4 and 5, miniaturized and highthroughput versions of SBSDME are designed to analyze a larger number of samples simultaneously. To demonstrate the applicability of these strategies, they have been applied to the analysis of biological samples. Specifically, Chapter 4 is devoted to the determination of salivary cortisone and cortisol as biomarkers of various diseases, and in Chapter 5 two cannabinoids in saliva are determined as indicatives of cannabis consumption. Then, in Chapter 6, magnetic headspace adsorptive microextraction (M-HS-AME) is adapted and miniaturized for the determination of volatile compounds as biomarkers of lung cancer in saliva samples.
Finally, SECTION 3 describes the general conclusions derived from this Doctoral Thesis
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