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1.
Phys Chem Chem Phys ; 24(12): 7224-7230, 2022 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-35274636

RESUMEN

HCN in the gas form is considered as a primary nitrogen source for the synthesis of prebiotic molecules in extraterrestrial environments. Nevertheless, the research mainly focused on the reactivity of HCN and its derivatives in aqueous systems, often using external high-energy supply in the form of cosmic rays or high energy photons. Very few studies have been devoted to the chemistry of HCN in the gas phase or at the gas/solid interphase, although they represent the more common scenarios in the outer space. In this paper we report about the reactivity of highly pure HCN in the 150-300 K range at the surface of amorphous and crystalline Mg2SiO4 (forsterite olivine), i.e. of solids among the constituents of the core of cosmic dust particles, comets, and meteorites. Amorphous silica and MgO were also studied as model representatives of Mg2SiO4 structural building blocks. IR spectroscopic results and the HR-MS analysis of the reaction products revealed Mg2+O2- acid/base pairs at the surface of Mg2SiO4 and MgO to be key in promoting the formation of HCN oligomers along with imidazole and purine compounds, already under very mild temperature and HCN pressure conditions, i.e. in the absence of external energetic triggers. Products include adenine nucleobase, a result which supports the hypothesis that prebiotic molecular building blocks can be easily formed through surface catalytic processes in the absence of high-energy supply.


Asunto(s)
Gases , Meteoroides , Polvo , Medio Ambiente Extraterrestre/química , Silicatos
2.
J Nanosci Nanotechnol ; 18(8): 5854-5857, 2018 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-29458653

RESUMEN

The oligomerization of non-activated amino acids catalyzed by nanostrucrured mineral oxide surfaces holds promises as a sustainable route for the industrial production of polypeptides. To analyze the influence of the surface type on the catalytic process, we performed, via a mild Chemical Vapor Deposition approach, the oligomerization of Glycine on two samples of TiO2 nanoparticles characterized by different relative amounts of defective surface terminations. Based on infrared spectroscopy and mass spectrometry data, we show herein that the formation of peptide bonds on titania nanoparticles does not require highly energetic surface terminations, but can occur also on the most abundant and thermodynamically most stable {101} facets of nanosized anatase.

3.
Sci Justice ; 58(2): 85-89, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29526269

RESUMEN

Entomotoxicology involves the analysis of the presence and the effects of toxicological substances in necrophagous insects. Results obtained by entomotoxicological studies may assist in the investigation of both the causes and the time of death of humans and animals. Ethylene glycol (EG) is easy to purchase, sweet and extremely toxic. It may be consumed accidentally or purposefully, in an attempt to cause death for suicidal or homicidal intent. Several cases report fatalities of humans and animals. The present study is the first to examine the effects of EG on the survival, developmental rate and morphology of two blowfly species, (Diptera: Calliphoridae) typically found on corpses and carcasses: Lucilia sericata (Meigen) and L. cuprina (Wiedemann). Both species were reared on substrates (beef liver) spiked with three different concentrations of EG that could cause death in either a human or cat: 1/2LD50 (T1), LD50 (T2), 2LD50 (T3), in addition to a control treatment (C) with no EG. Results of this research show that: a) both species are unable to survive if reared on a food substrate spiked with the highest concentration of EG (T3), while lower and medium concentrations (T1, T2) affect, but not prevent, the survival and the completion of the life cycle of such species; b) adults of L. sericata eclose only in C and T1, while adults of L. cuprina in both C, T1, T2; however, c) the developmental time of both species reared in T1 and T2 is statistically slower than the control; d) the body length of the immatures of both of the species reared in T1 and T2 is statistically smaller than the control.


Asunto(s)
Dípteros/efectos de los fármacos , Dípteros/crecimiento & desarrollo , Glicol de Etileno/toxicidad , Larva/efectos de los fármacos , Larva/crecimiento & desarrollo , Pupa/efectos de los fármacos , Pupa/crecimiento & desarrollo , Animales , Entomología , Conducta Alimentaria , Ciencias Forenses , Oviposición
4.
Anal Bioanal Chem ; 409(29): 6831-6841, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28948317

RESUMEN

The presence of certain metals naturally contained inside raw materials (e.g., pigments) used to produce cosmetics for make-up may represent a serious concern for the final quality and safety of the product. The knowledge of the total concentration of metals is not sufficient to predict their reactivity and their toxicological profile. For these reasons, we set up a comprehensive approach to characterize the content of Co, Cr, and Ni in two raw materials for cosmetic production, a black iron oxide and a pearly pigment, and in a finished product, pearly powder eye shadow. Namely, besides the total metal concentrations, the speciation of chromium and the bioaccessibility of the three metals were assessed. Since no standard method is so far available for hexavalent chromium extraction from cosmetic samples, three approaches were compared (EPA 3060A method, IRSA 16 method, and a Na3PO4 extraction). Results show that Na3PO4 extraction is the most selective one. Cr(VI) was undetectable in black iron oxide and present at very low concentrations (about 0.3 mg/kg) in pearly pigment and in the pearly powder eye shadow samples. The extracted Cr(VI) concentrations are not related to the total Cr content in the samples. Bioaccessibility studies were performed by in vitro extractions with synthetic lacrimal fluids and sweat. Despite the wide range of metal concentrations in the samples, the amounts of bioaccessible elements were undetectable or very low (less than 0.4 mg/kg), thus suggesting that metals in the three samples are present in inert forms. Graphical abstract The possible leaching of metals from cosmetics to biological fluids. Spectroscopic and chromatographic techniques provide complementary information for an integrated bioanalytical approach to risk characterization.


Asunto(s)
Técnicas de Química Analítica/métodos , Cromo/análisis , Cobalto/análisis , Cosméticos/química , Níquel/análisis , Cromo/química
5.
Rapid Commun Mass Spectrom ; 30(24): 2617-2627, 2016 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-27706863

RESUMEN

RATIONALE: Nicotine and cotinine are, respectively, alkaloids produced mainly by the Solanaceae plant family, especially tobacco, and its most important human metabolite. These compounds are frequently found as contaminants in wastewater or landfill samples and they could be used to evaluate pollution by tobacco use. The aim of this study is to improve the knowledge about possible transformation pathways of nicotine and cotinine. This would help the identification of degradants by using HPLC coupled with a high resolving power mass analyzer (LTQ-Orbitrap). In addition, we evaluated toxicity on bioluminescent photobacteria to indicate possible relationships between the formation of transformation products and their toxic effects. METHODS: The transformation of nicotine and cotinine and the formation of intermediate products were evaluated adopting titanium dioxide as photocatalyst. The structural identification of photocatalytic transformation products of these two alkaloids was based on LC/multistage MS experiments. High-resolution MS allowed the elemental composition of these products to be hypothesized. The evolution of toxicity as a function of the irradiation time was also studied using a bioluminescent photobacterium (Vibrio fischeri) test. RESULTS: Several products were formed and characterized using HPLC/HRMSn . The main photocatalytic pathways involving nicotine and cotinine appear to be hydroxylation, demethylation and oxidation. Nine degradants were formed from nicotine, including cotinine. Seven degradants were generated from cotinine. There is no transformation product in common between the two studied molecules. CONCLUSIONS: The study of photocatalytic degradation allowed us to partially simulate human metabolism and the environmental transformation of the bioactive alkaloid nicotine. We searched for some of the identified transformation products in river water and landfill percolate by solid-phase extraction and HPLC/HRMS and eventually their presence was confirmed. These new findings could be of interest in further metabolism and environmental pollution studies. Copyright © 2016 John Wiley & Sons, Ltd.


Asunto(s)
Aliivibrio fischeri/metabolismo , Cotinina/metabolismo , Nicotina/metabolismo , Aliivibrio fischeri/efectos de la radiación , Biotransformación/efectos de los fármacos , Catálisis/efectos de la radiación , Cotinina/química , Luz , Espectrometría de Masas , Nicotina/química , Nicotiana/química
6.
Environ Res ; 137: 141-6, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25531819

RESUMEN

BACKGROUND: Air pollution and tobacco smoke can induce negative effects on the human health and often leads to the formation of oxidative stress. OBJECTIVE: The purpose of this study was to clarify the role of the urbanization degree and of passive exposure to tobacco smoke in the formation of oxidative stress. Thus, a group of non-smoking adolescents was recruited among those who live and attend school in areas with three different population densities. To each subject a spot of urine was collected to quantify 15-F2t isoprostane as a marker of oxidative stress and cotinine as a marker of passive exposure to tobacco smoke. Furthermore, respiratory functionality was also measured. RESULTS: Multiple linear regression analysis results showed a direct correlation (p<0.0001) of 15-F2t isoprostane with both the urbanization and passive smoke. Lung function parameters proved significantly lower for the subjects living in the most populous city of Torino. CONCLUSION: This remarks the negative effect that urbanization has on the respiratory conditions. Lastly, lung functionality presented a low inverse correlation with 15-F2t isoprostane, suggesting an independent mechanism than that of the urban factor.


Asunto(s)
Cotinina/orina , Exposición a Riesgos Ambientales , Isoprostanos/orina , Pulmón/fisiopatología , Contaminación por Humo de Tabaco/efectos adversos , Adolescente , Biomarcadores/orina , Niño , Dinoprost/análogos & derivados , Monitoreo del Ambiente , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Italia , Masculino , Estrés Oxidativo , Medición de Riesgo , Población Rural , Espirometría , Población Urbana
7.
Angew Chem Int Ed Engl ; 53(18): 4671-4, 2014 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-24616011

RESUMEN

In situ IR and mass spectrometry evidence for the catalytic formation on SiO2 and TiO2 surfaces of glycine oligomers (poly-Gly) up to 16 units long by successive feeding with monomers from the vapor phase is presented. Parallel experiments carried out on hydroxyapatite resulted in the unreactive adsorption of Gly, thus indicating that the oligomerization was specifically catalyzed by the surfaces of SiO2 and TiO2 . Furthermore, the poly-Gly moved on the surface when contacted with H2 O vapor and formed self-assembled aggregates containing both helical and ß-sheet-like structural motifs. These results indicate that polypeptides formed by the condensation of amino acids adsorbed on a mineral surface can evolve into structured supramolecular assemblies.


Asunto(s)
Glicina/química , Fragmentos de Péptidos/química , Dióxido de Silicio/química , Titanio/química , Durapatita/química , Nanopartículas/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espectrofotometría Infrarroja , Agua/química
8.
J Pediatr Gastroenterol Nutr ; 56(4): 390-6, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23149807

RESUMEN

OBJECTIVE: The study was aimed at evaluating the effect of prolonged refrigeration of fresh human milk (HM) on its fatty acid profile, free fatty acid content, lipase activities, and oxidative status. METHODS: HM from mothers of preterm newborns was collected, pooled, and placed in the neonatal intensive care unit (NICU) refrigerator. Pooled milk was aliquoted and analyzed within 3 hours of collection, and after 24, 48, 72, and 96 hours of storage. The milk samples were analyzed for pH, total and free fatty acid profile, lipase activity at room temperature and at 4°C, lipase activity at room temperature in presence of sodium cholate (bile salt-dependent lipase), total antioxidant capacity, thiobarbituric acid reactive species, malondialdehyde, and conjugated diene concentration. The experiment was replicated in 3 independent trials. RESULTS: Prolonged refrigeration did not affect the fatty acid composition of breast milk, and preserved both its overall oxidative status and the activity of HM lipolytic enzymes. In particular, bile salt-dependent lipase activity, long-chain polyunsaturated fatty acids, and medium-chain saturated fatty acid concentrations were unaffected for up to 96 hours of refrigerated storage. CONCLUSIONS: Prolonged refrigeration of fresh HM for 96 hours maintained its overall lipid composition. The limited lipolysis during storage should be ascribed to the activity of lipoprotein lipase, responsible for the decrease in pH. Our study demonstrates that infants who receive expressed milk stored for up to 96 hours receive essentially the same supply of fatty acids and active lipases as do infants fed directly at the breast.


Asunto(s)
Grasas de la Dieta/análisis , Almacenamiento de Alimentos , Lipasa/metabolismo , Peroxidación de Lípido , Lipólisis , Leche Humana/química , Antioxidantes/análisis , Antioxidantes/metabolismo , Grasas de la Dieta/metabolismo , Estabilidad de Enzimas , Ácidos Grasos/análisis , Ácidos Grasos/metabolismo , Ácidos Grasos no Esterificados/análisis , Ácidos Grasos no Esterificados/metabolismo , Femenino , Humanos , Concentración de Iones de Hidrógeno , Italia , Peróxidos Lipídicos/análisis , Peróxidos Lipídicos/metabolismo , Lipoproteína Lipasa/metabolismo , Malondialdehído/análisis , Malondialdehído/metabolismo , Leche Humana/enzimología , Leche Humana/metabolismo , Periodo Posparto , Refrigeración , Factores de Tiempo
9.
Forensic Sci Int ; 335: 111310, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35468576

RESUMEN

In the investigation of gunshot deaths, Bloodstains Pattern Analysis (BPA) and, in particular, backspatter patterns found on the body of the suspect/victim and on the surfaces close to the entrance wound of the bullet can provide investigators with important indications on the dynamics of the events. Backspatter patterns have, however, morphological characteristics common to other bloodstains of different origin, so, in order to positively identify them, a possible solution is represented by their sampling, using an aluminum stub for electron microscopy, for the detection of gunshot residues (GSR) present. The latter, however, if present below the small blood crusts, could be difficult to detect during analysis by Scanning Electron Microscopy/Energy Dispersive X-ray microanalysis (SEM/EDX). In this preliminary study we propose the treatment of the stub surface with a solution based on sodium hypochlorite and calcium chloride, in order to remove/reduce the blood crusts present on the stub surface.


Asunto(s)
Suelo , Heridas por Arma de Fuego , Humanos , Microscopía Electrónica de Rastreo , Manejo de Especímenes
10.
Chemosphere ; 303(Pt 2): 134895, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35568219

RESUMEN

The fungicide tebuconazole (TBCZ) is expected to undergo negligible direct photolysis in surface freshwaters, but it can be degraded by indirect photochemistry. TBCZ mainly reacts with hydroxyl radicals and, to a lesser extent, with the triplet states of chromophoric dissolved organic matter (3CDOM*). Indirect photochemistry is strongly affected by environmental conditions, and TBCZ lifetimes of about one week are expected in sunlit surface waters under favourable circumstances (shallow waters with low concentrations of dissolved organic carbon, DOC, during summer). In these cases, the time trend would follow pseudo-first order kinetics (mono-exponential decay). Under less favourable conditions, photoinduced degradation would span over a few or several months, and TBCZ phototransformation would depart from an exponential trend because of seasonally changing sunlight irradiance. The TBCZ phototransformation products should be less toxic than their parent compound,thus photodegradation has potential to decrease the environmental impact of TBCZ. Hydroxylation is a major TBCZ transformation route, due to either OH attack, or one-electron oxidation sensitised by 3CDOM*, followed by reaction of the oxidised transient with oxygen and water.


Asunto(s)
Fungicidas Industriales , Contaminantes Químicos del Agua , Agua Dulce/química , Cinética , Procesos Fotoquímicos , Fotólisis , Luz Solar , Triazoles , Contaminantes Químicos del Agua/análisis
11.
Front Vet Sci ; 9: 830157, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35433921

RESUMEN

Sarcoptic mange is considered the main driver of demographic declines occurred in the last decades in Iberian ibex (Capra pyrenaica) populations. Mass treatment campaigns by administration of in-feed acaricides are used as a measure to mitigate the impact of mange in the affected populations. However, there are no data on ivermectin (IVM) pharmacokinetics in this wild caprine, and the treatment through medicated feed is not endorsed by evidence on its effectiveness. The aim of this study is to determine the pharmacokinetic profile of IVM in plasma samples of ibexes after the experimental oral administration of IVM, using high performance liquid chromatography (HPLC) with automated solid phase extraction and fluorescence detection. A dose of 500 µg of IVM per body weight was orally administered in a feed bolus to nine healthy adult ibexes (seven males and two females). Blood samples were collected by jugular venipuncture into heparin-coated tubes at day 1, 2, 3, 4, 7, 10, 15, and 45 post-administration (dpa). The highest plasma concentration of IVM (Cmax = 3.4 ng/ml) was detected 24 h after the oral administration (T1), followed by a rapid decrease during the first week post-administration. Our results reveal that plasma IVM concentration drops drastically within 5 days of ingestion, questioning the effectiveness of a single in-feed dose of this drug to control sarcoptic mange. To the best of our knowledge, this is the first study on plasma availability of oral IVM in ibexes and in any wild ungulate species.

12.
Sci Total Environ ; 796: 148953, 2021 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-34328879

RESUMEN

Membrane distillation is a promising technology to desalinate hypersaline produced waters. However, the organic content can foul and wet the membrane, while some fractions may pass into the distillate and impair its quality. In this study, the applicability of the traditional Fenton process was investigated and preliminarily optimized as a pre-treatment of a synthetic hypersaline produced water for the following step of membrane distillation. The Fenton process was also compared to a modified Fenton system, whereby safe iron ligands, i.e., ethylenediamine-N,N'-disuccinate and citrate, were used to overcome practical limitations of the traditional reaction. The oxidation pre-treatments achieved up to 55% removal of the dissolved organic carbon and almost complete degradation of the low molecular weight toxic organic contaminants. The pre-treatment steps did not improve the productivity of the membrane distillation process, but they allowed for obtaining a final effluent with significantly higher quality in terms of organic content and reduced Vibrio fischeri inhibition, with half maximal effective concentration (EC50) values up to 25 times those measured for the raw produced water. The addition of iron ligands during the oxidation step simplified the process, but resulted in an effluent of slightly lower quality in terms of toxicity compared to the use of traditional Fenton.


Asunto(s)
Destilación , Contaminantes Químicos del Agua , Peróxido de Hidrógeno , Oxidación-Reducción , Aguas Residuales , Agua , Contaminantes Químicos del Agua/toxicidad
13.
Biomed Chromatogr ; 24(4): 358-66, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19642085

RESUMEN

A fast screening protocol was developed and validated for the simultaneous determination of 15 beta(2)-agonists in human urine (bambuterol, cimbuterol, clenbuterol, fenoterol, formoterol, isoproterenol, mapenterol, metaproterenol, procaterol, ractopamine, ritodrine, salbutamol, salmeterol, terbutaline, tulobuterol). The overall sample processing includes deconjugation with enzyme hydrolysis, liquid-liquid extraction, followed by derivatization of the extract and detection of beta(2)-agonists trimethylsilyl-derivatives by fast-gas chromatography/electron impact-mass spectrometry (fast-GC/EI-MS). Sample extraction and derivatization were optimized with the purpose of improving recoveries and reaction yields for a variety of analytes with different structures simultaneously, while keeping the procedure simple and reliable. Validation parameters were determined for each analyte under investigation, including selectivity, linearity, intra- and inter-assay precision, extraction recoveries and signal to noise ratio (S/N) at the lowest calibration level. Fast-GC/MS sequences, based on the use of short columns, high carrier-gas velocity and fast temperature ramping, allow considerable reduction of the analysis time (7 min), while maintaining adequate chromatographic resolution. The overall GC cycle time was less than 9 min, allowing a processing rate of 6 samples/h. High MS-sampling rate, using a benchtop quadrupole mass analyzer, resulted in accurate peak shape definition under both scan and selected ion monitoring modes, and high sensitivity in the latter mode. The method was successfully tested on real samples arising from clinical treatments. Copyright (c) 2009 John Wiley & Sons, Ltd.


Asunto(s)
Agonistas de Receptores Adrenérgicos beta 2 , Agonistas Adrenérgicos beta/orina , Cromatografía de Gases y Espectrometría de Masas/métodos , Agonistas Adrenérgicos beta/química , Albuterol/análogos & derivados , Albuterol/orina , Asma/orina , Humanos , Análisis de los Mínimos Cuadrados , Reproducibilidad de los Resultados , Xinafoato de Salmeterol , Sensibilidad y Especificidad
14.
J Hazard Mater ; 393: 122413, 2020 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-32126419

RESUMEN

The Fenton reaction is an effective advanced oxidation process occurring in nature and applied in engineering processes toward the degradation of harmful substances, including contaminants of emerging concern. The traditional Fenton application can be remarkably improved by using iron complexes with organic ligands, which allow for the degradation of contaminants at near-neutral pH and for the reduction of sludge production. This work discusses the mechanisms involved both in the classic Fenton process and in the presence of ligands that coordinate iron. Cyclohexane was selected as mechanistic probe, by following the formation of the relevant products, namely, cyclohexanol (A) and cyclohexanone (K). As expected, the classic Fenton process was associated with an A/K ratio of approximately 1, evidence of a dominant free radical behavior. Significantly, the presence of widely common natural and synthetic carboxyl ligands selectively produced mostly the alcoholic species in the first oxidation step. A ferryl-based mechanism was thus preferred when iron complexes were formed. Common iron ligands are here proven to direct the reaction pathway towards a selective metal-based catalysis. Such a system may be more easily engineered than a free radical-based one to safely remove hazardous contaminants from water and minimize the production of harmful intermediates.

15.
Toxins (Basel) ; 12(4)2020 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-32326118

RESUMEN

The diffusion of the legalization of cannabis for recreational, medicinal and nutraceutical uses requires the development of adequate analytical methods to assure the safety and security of such products. In particular, aflatoxins are considered to pose a major risk for the health of cannabis consumers. Among analytical methods that allows for adequate monitoring of food safety, immunoassays play a major role thanks to their cost-effectiveness, high-throughput capacity, simplicity and limited requirement for equipment and skilled operators. Therefore, a rapid and sensitive enzyme immunoassay has been adapted to measure the most hazardous aflatoxin B1 in cannabis products. The assay was acceptably accurate (recovery rate: 78-136%), reproducible (intra- and inter-assay means coefficients of variation 11.8% and 13.8%, respectively), and sensitive (limit of detection and range of quantification: 0.35 ng mL-1 and 0.4-2 ng mL-1, respectively corresponding to 7 ng g-1 and 8-40 ng g-1 ng g-1 in the plant) and provided results which agreed with a HPLC-MS/MS method for the direct analysis of aflatoxin B1 in cannabis inflorescence and leaves. In addition, the carcinogenic aflatoxin B1 was detected in 50% of the cannabis products analyzed (14 samples collected from small retails) at levels exceeding those admitted by the European Union in commodities intended for direct human consumption, thus envisaging the need for effective surveillance of aflatoxin contamination in legal cannabis.


Asunto(s)
Aflatoxina B1/análisis , Cannabis/química , Cromatografía Líquida de Alta Presión , Contaminación de Medicamentos , Técnicas para Inmunoenzimas , Espectrometría de Masas en Tándem
16.
Chemosphere ; 246: 125705, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-31891848

RESUMEN

The photochemical fate of the herbicide bentazone was assessed by lab experiments and modeling tools. Experimental and modeling results showed that bentazone is mainly photodegraded by direct photolysis in natural water samples, even in the presence of dissolved organic matter (DOM) that can act as light-screening agent, photosensitizer and scavenger of reactive species. Even when it was dissolved in natural water samples containing different DOM amounts, the phototransformation kinetics of bentazone was unchanged compared to irradiation runs in ultrapure water. This finding suggests that the DOM and the other components of our samples did not affect the direct photolysis of bentazone by light-absorption competition, at least at the experimental optical path lengths, and did not induce significant indirect photodegradation by producing reactive transient species. Photochemical modeling in a lake-water photoreactivity scenario corroborated the observed experimental results, showing the predominant role of direct photolysis in the overall (direct + indirect) photodegradation of bentazone at different water depths and DOM contents. However, the model predicted a minor but non-negligible contribution of indirect photochemistry (i.e., reactions triggered by HO•, CO3•- and 3CDOM*) to the herbicide degradation. This contribution (especially by 3CDOM*) could become crucial in deep and DOM-rich water bodies. Finally, several photoproducts formed by direct photolysis and HO•-induced photodegradation were identified, which should not be particularly toxic for aquatic organisms and Vibrio fischeri bacteria.


Asunto(s)
Benzotiadiazinas/química , Procesos Fotoquímicos , Contaminantes Químicos del Agua/química , Agua Dulce/química , Herbicidas , Cinética , Fotoquímica , Fotólisis , Contaminantes Químicos del Agua/análisis
17.
J Pharm Biomed Anal ; 176: 112764, 2019 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-31401460

RESUMEN

An accurate and specific gas chromatography-mass spectrometry (GC-MS) method was optimized to quantify specific polyunsaturated fatty acids (PUFAs) in plasma and in erythrocyte membranes for clinical purposes. The developed and fully-validated method showed optimal linearity in addition to adequate results in terms of accuracy, intra-day and inter-day precision. By adopting the Matrix-Corrected Calibration approach on all the biological matrices tested, both the constant and the proportional errors of the developed analytical methodology were considered to assure that the method was not affected by matrix bias. Moreover, a pilot study involving patients in parental nutrition with two different compositions of the administered fat emulsion was performed. The comparison of results obtained in these patients with a group of healthy subjects (i.e. control population) showed significant differences in the collected values of PUFAs in both plasma and erythrocyte membranes, thus providing evidence that the described GC-MS method could be employed as a simple tool for fast and accurate PUFAs analysis aimed at optimizing parenteral nutrition protocols.


Asunto(s)
Monitoreo de Drogas/métodos , Eritrocitos/química , Ácidos Grasos Insaturados/sangre , Cromatografía de Gases y Espectrometría de Masas/métodos , Adolescente , Adulto , Anciano , Calibración , Monitoreo de Drogas/normas , Emulsiones Grasas Intravenosas/administración & dosificación , Ácidos Grasos Insaturados/administración & dosificación , Femenino , Cromatografía de Gases y Espectrometría de Masas/normas , Humanos , Masculino , Persona de Mediana Edad , Nutrición Parenteral/métodos , Proyectos Piloto , Adulto Joven
18.
Analyst ; 133(4): 525-31, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18365123

RESUMEN

Time resolved measurements show that during a desorption electrospray ionization (DESI) experiment, the current initially rises sharply, followed by an exponential decrease to a relatively steady current. When the high voltage on the spray emitter is switched off, the current drops to negative values, suggesting that the direction of current flow in the equivalent DESI circuit is reversed. These data demonstrate that the DESI source behaves as a dc capacitor and that the addition of a surface between the sprayer and the counter electrode in DESI introduces a new electrically active element into the system. The charging and discharging behavior was observed using different surfaces and it could be seen both by making current measurements on a plate at the entrance to the mass spectrometer as well as by measuring ion current in the linear ion trap within the vacuum system of the mass spectrometer. The magnitude of the steady state current obtained without analyte present on the surface is different for different surface materials, and different capacitor time constants of the equivalent RC circuits were calculated for different DESI surfaces. The PTFE surface has by far the greatest time constant and is also able to produce the highest DESI currents. Surface properties play a crucial role in charge transfer during DESI in addition to the effects of the chemical properties of the analyte. It is suggested that surface energy (wettability) is an important factor controlling droplet behavior on the surface. The experimental data are correlated with critical surface tension values of different materials. It is proposed, based on the results presented, that super-hydrophobic materials with extremely high contact angles have the potential to be excellent DESI substrates. It is also demonstrated, using the example of the neurotransmitter dopamine, that the surface charge that develops during a DESI-MS experiment can cause electrochemical oxidation of the analyte.

19.
J Pharm Biomed Anal ; 48(2): 462-6, 2008 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-18450405

RESUMEN

The analysis of diuretic compounds has become of great concern because of their extensive use both in therapy and in illicit treatments (such as masking agents in sport doping and drug abuse). The variety of chemical structures of this class of drugs encouraged the development of new methods and techniques of analysis, especially as regards to acidic compounds. LC/MS has so grown to be the reference technique for this kind of analysis in forensic and anti-doping confirmation purposes. Multiple stage MS permits identification of single drugs with high selectivity, but some unexpected pathways could weaken the entire process. In this work we aim to explain some unusual fragmentation steps using high-resolution MSn. For example, in the case of amiloride an intense product ion in MS3 analysis generates an apparent loss of 10Da. Water adduct formation and successive carbon monoxide elimination can explain this uncommon behavior, which was studied using different ion traps. Bendroflumethiazide MSn spectra show instead three successive HF losses, in spite of the presence of a radical site in the parent structure. Homolytic cleavages with radical ion production occur also in the case of protonated positive ion of ethacrynic acid (loss of chlorine radical) showing that such fragmentation behavior is not so rare as generally reported. Different ionization modes were studied and a tentative correlation with acidic-base properties was done. Multiple stage high-resolution mass spectra of positive and negative ions were discussed.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Diuréticos/análisis , Espectrometría de Masas/métodos
20.
J Med Entomol ; 55(1): 51-58, 2018 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-29029268

RESUMEN

Entomotoxicology studies employ analytical methods and instrumentation to detect chemical substances in carrion insects feeding from the decomposing tissues. The identification of such chemicals may determine the cause of death and may be used for the estimation of the minimum time since death. To date, the main focus of entomotoxicological studies has been the detection of drugs, whereas little information concerns the effects of pesticides on blowflies. Pesticides are generally freely available and more affordable than drugs but they can also be a home hazard and an accessible candidate poison at a crime scene. A QuEChERS extraction method followed by Gas chromatography-mass spectrometry (GC-MS) analysis was developed for the detection of α- and ß-endosulfan (organochlorine insecticide and acaricide) in Calliphora vomitoria L. (Diptera: Calliphoridae) and validated. Furthermore, the effects of endosulfan on the morphology, development time and survival of the immature blowflies were investigated. Larvae were reared on liver substrates homogeneously spiked with aliquots of endosulfan corresponding to the concentrations found in body tissues of humans and animals involved in endosulfan poisoning. Results demonstrated that the combination of QuEChERS extraction and GC-MS provide an adequate methods to detect both α- and ß-endosulfan in blowfly immatures. Furthermore, the presence of α- and ß-endosulfan in the food source 1) prevented C. vomitoria immatures reaching the pupal instar and, therefore, the adult instar at high concentrations, 2) did not affect the developmental time of blowflies at low concentrations 3) affected the size of immatures only at high concentrations, resulting in significantly smaller larvae.


Asunto(s)
Dípteros/química , Ecotoxicología/métodos , Endosulfano/análisis , Insecticidas/análisis , Animales , Dípteros/crecimiento & desarrollo , Cromatografía de Gases y Espectrometría de Masas/métodos , Larva/química , Larva/crecimiento & desarrollo , Pupa/química , Pupa/crecimiento & desarrollo
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