La dimensión religiosa del hombre

Fil: Todolí, José. Universidad Complutense de Madri

High temperature total consumption sample introduction system coupled to microwave plasma optical emission spectrometry (MIP-OES) for the analysis of aqueous samples

The high temperature torch integrated sample introduction system (hTISIS) is coupled to microwave plasma optical emission spectrometry (MIP-OES) for the first time. The goal of this work is to develop an accurate analysis of digested samples under continuous sample aspiration mode by coupling the hTISIS to a MIP-OES instrument. To achieve this, different operating conditions such as, nebulization flow rate, liquid flow rate and the spray chamber temperature were optimized in terms of sensitivity, limits of quantification (LOQs) and background equivalent concentration (BECs) for the determination of Ca, Cr, Cu Fe, K, Mg, Mn, Na, Pb and Zn, and these values were compared with those reported with a conventional sample introduction system. Under optimum conditions (0.8–1 L min−1, 100 μL min−1 and 400 ᵒC, respectively), the hTISIS improved MIP-OES analytical figures of merit and shortened 4-times wash out times with respect to a conventional cyclonic spray chamber, reporting an enhancement factor in the sensitivity among 2–47 times and LOQs from 0.9 to 360 μg kg−1. Once the best operating conditions were set, the magnitude of the interference caused by 15 different acid matrices (2, 5 and 10% w/w of HNO3, H2SO4, HCl and mixtures of HNO3 with H2SO4 and HNO3 with HCl) was significantly lower for the former device. Finally, 6 different digested oily samples (used cooking oil, animal fat, corn oil and the same samples after a filtration step) were analyzed by means of an external calibration approach based on the use of multielemental standards prepared in 3% (w/w) HCl solution. The obtained results were compared against those supplied by a conventional methodology employing an inductively coupled plasma optical emission spectrometry, ICP-OES, instrument. It was clearly concluded that the hTISIS coupled to MIP-OES afforded similar concentrations as compared to the conventional methodology

Armadura transversal en pilares de hormigón convencional con fibras de acero sometidos a flexo-compresión recta

[ES] Una de las funciones de la armadura transversal en elementos de hormigón convencional sometidos a flexocompresión recta, es la de impedir el pandeo de la armadura longitudinal pasiva. Es importante para que esta armadura transversal haga su función, determinar de forma correcta su separación. En la instrucción del hormigón EHE- 08 (Ministerio de Fomento, 2008) así como en otras normativas como la ACI-318 (ACI Committee 318, 2008), se establece una relación entre el diámetro de la barra comprimida más delgada y la separación entre estribos pero sin hacer referencia a ningún tipo de hormigón en concreto ni a ningún cálculo en el que se pueda utilizar esta última variable. El objeto de este trabajo fin de grado es determinar si al añadir fibras metálicas a un elemento de hormigón convencional se aumenta la deformación a la que se produce el pandeo y si la rotura del recubrimiento precede al pandeo. Para ello se van a ensayar dos especímenes sometiéndolos de manera controlada a una situación de carga en la que se provoque el pandeo de la armadura longitudinal pasiva, uno de ellos reforzado con fibras de acero.[EN] One of the functions of the transverse reinforcing bars in reinforced concrete elements under axial flexo-compression loads is to prevent the passive longitudinal bars buckling. So that this transversal reinforcing bars do its correct function it’s important to determinate correctly its separation. At the concrete instruction EHE-08 (Ministerio de Fomento, 2008) the same way as other regulations for instance ACI-318 (ACI Committee 318, 2008), it´s established a relationship between the diameter of the thinner passive longitudinal bar and the stirrups but doing neither reference to any kind of concrete nor calculation where to add this last variable. The aim of this final degree job is to determinate whether the buckling´s deformation can increase adding steel fibers to a reinforced concrete element and is the break of the concrete cover precedes the buckling. To this end, two columns are going to be tested under controlled load situations where the buckling of the longitudinal passive bars is caused. One of both columns is reinforced with steel fibers.Martínez Todolí, LJ. (2015). Armadura transversal en pilares de hormigón convencional con fibras de acero sometidos a flexo-compresión recta. http://hdl.handle.net/10251/54316.TFG

Speciation analysis by small-bore HPLC coupled to ICP-MS

Although high-performance liquid chromatography with inductively-coupled mass spectrometry (HPLC-ICP-MS) has established itself as the analytical technique of choice for elemental speciation analysis, there are remaining limitations, mainly concerning post-column dispersion effects and degradation of the ICP stability and ionization efficiency due to organic or saline mobile phases. The application of small-bore columns in conjunction with low dead-volume interfaces has proved very useful for overcoming these problems, since they can provide lower matrix load and reduced peak dispersion, along with minimization of sample size and solvent consumption, faster chromatographic separations, and better resolution and sensitivity. Since we expect more work to be reported in this area, we review recent research in the field of speciation analysis by small-bore HPLC-ICP-MS, with the emphasis on significant advances in methods and instrumentation, relevant applications and current limitations.Amanda Terol thanks the Fundación Ramón Areces for the postdoctoral grant (25th edition).This work was carried out in the frame of the Italian National Project PRIN-2010AXENJ8

Liquid-sample introduction in plasma spectrometry

Plasma-spectrometry techniques, namely inductively coupled plasma atomic emission spectrometry (ICP-AES) and plasma-based mass spectrometry (MS), are the most commonly used in analytical laboratories for elemental analysis in a wide variety of samples. In these techniques, the quality of the analysis strongly depends on appropriate selection of the sample-introduction system. For liquid samples, it basically comprises a nebulizer, which transforms the bulk solution into an aerosol, and a spray chamber, which modifies the characteristics of this aerosol and transports it to the plasma base through an injector tube. Sometimes, a desolvation system is incorporated to reduce the solvent load into the plasma. This article describes the different components of the sample-introduction system, emphasizing their main advantages and drawbacks. A review of the processes that affect the aerosol between generation and reaching the plasma is also included

Localized Quantitative Analysis of Polymeric Films through Laser Ablation–Inductively Coupled Plasma Mass Spectrometry

The present work shows, for the first time, the application of laser ablation connected to inductively coupled plasma mass spectrometry (LA-ICP-MS) to the localized quantitative analysis of inclusions in polymeric industrial films. The multielemental mapping capabilities of LA-ICP-MS has allowed to chemically examine unique defects appeared during the plastic processing. This analytical tool is perfectly suited to detect elements such as Al, Mg, Zr, Ti, Cr, P, Pb, Sb, Zn, and Si in those inclusions. A method for multielemental quantitative analysis of these defects has been developed in the present work. The profiling for more than 100 different defects in three samples has demonstrated that more than 50% of these inclusions contain aggregates of some of the aforementioned elements. Therefore, the distribution of elements used as additives or present in catalysts must be carefully controlled during the production of polymeric films in order to avoid degradation in their performance.Funding acquisition M.B. and J.L.T. Authors wish to thank to Total Research and Technology and to the Spanish Ministry of Science, Innovation and Universities for the financial support (project ref. PGC2018-100711-B-I100)

Application of Dispersive Liquid–Liquid Aerosol Phase Extraction to the Analysis of Total and Individual Phenolic Compounds in Fried Extra Virgin Olive Oils

Seventeen extra virgin olive oil samples from Valencian Community (Spain) were submitted to a domestic-frying process (180 °C) during different degradation times (5, 10, 30, 60, 120 min). A dispersive liquid–liquid aerosol phase extraction by using a methanol/water (50:50) extracting solution was used to isolate the polyphenol fraction. Total phenolic content (TPC) was determined, whereas the determination of seven individual target polyphenolic compounds (hydroxytyrosol, tyrosol, oleuropein, vanillic acid, p-coumaric acid, ferulic acid, and vanillin) was carried out by using ultrahigh-performance liquid chromatography coupled to a tandem mass spectrometer. Statistically significant differences in the TPC values were found for Blanqueta and Manzanilla samples from different harvesting years. The domestic-frying process impacted the TPC and the individual phenolic compounds content. Thermal treatment for 2 h gave rise to a 94% decrease in the TPC. A first-order kinetic model was suitable to accurately describe the degradation of the individual phenolic compounds.The authors wish to thank the Spanish Ministry of Science, Innovation, and Universities for the financial support (project ref. PID2021-127566NB-I00)

Profiling of Organic Compounds in Bioethanol Samples of Different Nature and the Related Fractions

Forty-one bioethanol real samples and related fractions, together with a biobutanol sample, have been analyzed with gas chromatography coupled to either mass spectrometry (GC–MS) or flame ionization detection (GC–FID). Bioethanol with different water contents, samples originated from several sources of biomass, first- as well as second-generation specimens, distillation fractions, samples stocked in containers made of four different materials, and, finally, a biobutanol sample have been analyzed. The number of the compounds found through GC–MS has been 130, including alcohols, aldehydes, ketones, esters, ethers, nitrogen compounds, organic acids, furane derivates as well as other species (e.g., limonene). Afterward, a quantitative determination of major components of bioethanol has been carried out. The achieved results have revealed that, besides ethanol and, in some cases, water, species such as acetaldehyde, methanol, and higher alcohols, as well as 1,1-diethoxyethane, may be present at concentrations above 500 mg L–1. While the source of bioethanol (nature of the raw material, ethanol generation, or water content) has a direct impact on its volatile organic compound (VOC) profile, the material of the container where the biofuel has been stored does not play a significant role. Finally, the results have demonstrated that, for a given production process, different distillation fractions contain unequal VOC profiles.Authors are grateful to the Spanish Ministry of Science, Innovation and Universities for the financial support (Project Ref. PGC2018-100711-B-I00). C.S. thanks to the Ministry of Education, Spain for the contract FPU 13/01438

Determination of fat-soluble vitamins in vegetable oils through microwave-assisted high-performance liquid chromatography

In this manuscript, a study of the effect of microwave radiation on the high-performance liquid chromatography separation of tocopherols and vitamin K1 was conducted. The novelty of the application was the use of a relatively low polarity mobile phase in which the dielectric heating effect was minimized to evaluate the nonthermal effect of the microwave radiation over the separation process. Results obtained show that microwave-assisted high-performance liquid chromatography had a shorter analysis time from 31.5 to 13.3 min when the lowest microwave power was used. Moreover, narrower peaks were obtained; hence the separation was more efficient maintaining or even increasing the resolution between the peaks. This result confirms that the increase in mobile phase temperature is not the only variable for improving the separation process but also other nonthermal processes must intervene. Fluorescence detection demonstrated better signal-to-noise compared to photodiode arrayed detection mainly due to the independent effect of microwave pulses on the baseline noise, but photodiode array detection was finally chosen as it allowed a simultaneous detection of nonfluorescent compounds. Finally, a determination of the content of the vitamin E homologs was carried out in different vegetable oils. Results were coherent with those found in the literature

Elevated Lead, Nickel, and Bismuth Levels in the Peritoneal Fluid of a Peritoneal Endometriosis Patient without Toxic Habits or Occupational Exposure following a Vegetarian Diet

Potentially toxic elements (PTEs), found as environmental contaminants, have been related to endometriosis disease. In this context, the peritoneal fluid (PF) matrix has been poorly studied despite its importance. PF is the environment in which endometriotic lesions reside and communicate with surrounding tissues including tissues and nerve cells. In this work, our investigation group reports the special case of a peritoneal endometriosis patient presenting elevated lead, nickel, and bismuth levels in PF. This patient reported following a vegetarian diet and no toxic habits or occupational exposure. In conclusion, the elevated levels of PTEs found may result from a vegetarian diet or an unidentified environmental exposure source. This report provides new insights regarding the possible etiology of endometriosis disease and potential biomarkers for its diagnosis in early stages, although additional research is needed.This study was funded by the Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana (UGP-19-042 and UGP-20-039). A.L.-B. is supported by the European Social Fund and the Generalitat Valenciana under a Ph.D. contract (ACIF–2021/243)