Determinación de herbicidas derivados de la urea en aguas y vegetales

RESUMEN La Legislación de la Unión Europea establece límites muy rigurosos para la presencia de residuos de herbicidas derivados de la urea en aguas y en alimentos. Muchos de estos herbicidas son termolábiles y se descomponen durante el análisis por cromatografía de gases (CG), si bien se pueden determinar de manera indirecta a partir de los productos de degradación. El presente trabajo se propone como objetivos; estudiar el comportamiento de herbicidas derivados de la urea en CG con columnas capilares, evaluar su cuantificación en base a sus productos de degradación térmica, poner a punto un nuevo método de análisis en aguas y vegetales basado en la MEFS y la determinación por CG y aplicarlo al análisis de muestras reales. Para la consecución de los objetivos, se realizó un estudio bibliográfico de las propiedades físico-químicas y de las técnicas de extracción y de determinación, un estudio de los factores que influyen en el análisis por CG y en la MEFS desde matrices acuosas, se calcularon experimentalmente las constantes de distribución aparentes fibra/agua que rigen la MEFS y se aplicó la MEFS al análisis de residuos en aguas naturales y en muestras de vegetales. De los ensayos realizados se obtuvieron las siguientes conclusiones: Los herbicidas derivados de la urea se pueden determinar por CG con detectores de nitrógeno-fósforo, captura electrónica y espectrometría de masas a partir de sus productos de degradación térmica, formados en el inyector con buena sensibilidad y reproducibilidad. La temperatura del inyector es el factor más importante de todos los que influyen en la degradación térmica. La inyección a 300ºC facilita la degradación completa y reproducible de los herbicidas estudiados antes de su interacción con la fase estacionaria de la columna, por lo que es la temperatura elegida para llevar a cabo el resto de los análisis. El disolvente empleado en la inyección de fenilureas es muy importante, así se forman los ésteres carbámicos análogos con metanol y etanol y los isocianatos análogos con acetonitrilo, diclorometano y acetato de etilo mientras que metabenzotiazuron forma un benzotiazol, clorsulfuron una triazina y una fenilsulfonamida con independencia del disolvente empleado. La extracción en fase sólida con discos de octilsílice y posterior análisis de los extractos por cromatografía de gases permite la detección de los herbicidas seleccionados en aguas a concentraciones inferiores a 01 mg/L con recuperaciones speriores al 87%. La fibra de poliacrilato muestra mejor eficacia que las de polidimetilsiloxano para la extracción de los herbicidas permitiendo con un tiempo de extracción razonable (60min) alcanzar límites de detección inferiores a 01 mg/L. La MEFS con fibra de poliacrilato seguidas de CG permiten el análisis de los herbicidas seleccionados en aguas a concentraciones inferiores a 01 mg/L. En la MEFS, el aumento de la fuerza iónica y la dilución de la muestra disminuyen las interferencias de los ácidos húmicos en aguas y la de las partículas sólidas de origen vegetal en hortalizas, proporcionando límites de detección inferiores a los Límites Máximos de Residuos legislados para cebollas, patatas y zanahorias. La MEFS acoplada con la cromatografía de gases permite el análisis de ureas herbicidas en muestras de hortalizas a concentraciones muy por debajo de las exigidas en los Límites Máximos de Residuos Legislados. Una doble extracción realizada a pH 4 y a pH 11, es suficiente para conocer por separado los residuos que proceden de fenilureas herbicidas y los residuos de anilinas que son sus metabolitos La MEFS acoplada con CG no emplea disolventes y permite realizar la extracción desde muestras acuosas y la determinación de manera automática. Su aplicación en alimentos con alto contenido en agua, abre muchas posibilidades de futuro en el campo del análisis de residuos de plaguicidas en alimentos. ------------------------------------------------------------------------------------------------- SUMARY Substituted ureas are an important group of pesticides that are used as herbicides (phenylureas and sulfonylureas) and insecticides (benzoylureas). Phenylurea herbicides (PUHs) are largely used in field applications for pre- and post-emergence weed control in a variety of crops. The main groups of phenylurea herbicides are the N-phenyl-N,N-dialkylureas, N-phenyl-N-methoxyureas and compounds containing a heterocyclic group. More recently a group of sulfonylurea herbicides (SUHs) has been developed. Multiresidue and single residue methods generally consist of the same basic steps, but multiresidue methods allow the determination of a large number of pesticides in a single analysis, reducing thus time and cost of analysis. The Maximum Admissible Concentration (MAC) of pesticides in drinking water, defined by European Community Directive as 0.1 mg L-1 for individual pesticides and 0.5 mg L-1 for the sum of pesticides posed certain demands to the analytical methods for pesticide residue determination. Gas chromatographic conditions for determining eight phenylurea æchlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron and monuronæ and one sulfonylurea æchlorsulfuronæ herbicides were assessed. Degradation products of herbicides formed in the injector were used for identification. Most phenylureas formed their respective carbamic acid methyl esters, metabenzthiazuron formed an aminobenzothiazol and chlorsulfuron formed an aminotriazine plus a phenylsulfonamide. On-column injections of standards at different temperatures (from -30ºC to 400ºC) using columns with four stationary phases (BPX70, BPX35, BP10 and BPX5) were evaluated to identify the best chromatographic behaviour. The best suited column was BP10-30m. The effect of other factors such as injection mode, injector design, sample volume and the solvent used were also investigated. Instrument detection limits (IDLs) ranged from 0.05 ng for chlorsulfuron to 3 ng for monuron with the NPD and, from 0.01 ng for chlorsulfuron to 5 ng for metabenzthiazuron with the ECD. The RSDs (n=4) were lower than 4% at the 12-25 ng level. The method was applied to analyse surface waters extracted with C18 Empore disks with recoveries higher than 85%. Down to 0.1 mg·L-1 of each herbicide could be determined. Chlortoluron was found (11.4 mg·L-1) in a water sample and its presence was confirmed by gas chromatography-mass spectrometry. Degradation products of chlorsulfuron, chlortoluron, diuron, fluometuron, isoproturon, linuron, metabenzthiazuron, metobromuron, and monuron formed in the gas chromatographic injector were used for identification of their respective herbicide. The spectra of the derived compounds were obtained with a quadrupole mass spectrometric detector working in scan mode (20-450 amu). The solvent used for phenylurea herbicide injection (ethanol, methanol, dichloromethane, and acetonitrile) had influence on the generated compounds. When methanol and ethanol were used as solvents, the major products formed from phenylureas were carbamic acid esters. When acetonitrile or dichloromethane were used, the main derivatives were phenylisocyanates. However, chlorsulfuron and metabenzthiazuron generated a triazine plus a phenylsulfonamide and a benzothiazolamine respectively regardless of the assayed solvent. Linuron and diuron showed the same behaviour and gave degradation products with the same mass spectra. The thermal reactions occurred instantaneously in the injector block favoured by the high selected temperature (300ºC). The derived compounds from urea herbicides can be determined using a BP10-30m column and a Selected Ion Registering (SIR) program based on two to three m/z ions as a way to sensitively detect the presence of urea herbicides in environmental extracts. With standards in methanol the instrumental detection limits ranged from 0.1 pg for chlorsulfuron (detected as 2-chlorobenzensulfonamide) to 1 pg for monuron and metobromuron (both detected as their analogous carbamic acid methyl esters). The RSD were below 9 % at the 5 ng·L-1 level. The response was linear (r > 0.9986) within the 5 ng·L-1 to 25 mg·L-1 range. The unequivocal identification of some phenylurea herbicides was not always possible because some herbicides having analogous structures such as diuron and linuron gave the same derivative. Under the proposed conditions matrix effects were low enough to permit calibration with samples proceeding from ecological (non-pesticide treated) crops. Twelve commercial samples of each carrots, onions and potatoes were analyzed and only three samples of potatoes contained residues of linuron at levels below MRL

Preliminary Estimation of Deoxynivalenol Excretion through a 24 h Pilot Study

A duplicate diet study was designed to explore the occurrence of 15 Fusarium mycotoxins in the 24 h-diet consumed by one volunteer as well as the levels of mycotoxins in his 24 h-collected urine. The employed methodology involved solvent extraction at high ionic strength followed by dispersive solid phase extraction and gas chromatography determination coupled to mass spectrometry in tandem. Satisfactory results in method performance were achieved. The method"s accuracy was in a range of 68%108%, with intra-day relative standard deviation and inter-day relative standard deviation lower than 12% and 15%, respectively. The limits of quantitation ranged from 0.1 to 8 μg/Kg. The matrix effect was evaluated and matrix-matched calibrations were used for quantitation. Only deoxynivalenol (DON) was quantified in both food and urine samples. A total DON daily intake amounted to 49.2 ± 5.6 μg whereas DON daily excretion of 35.2 ± 4.3 μg was determined. DON daily intake represented 68.3% of the established DON provisional maximum tolerable daily intake (PMTDI). Valuable preliminary information was obtained as regards DON excretion and needs to be confirmed in large-scale monitoring studie

Determination of deoxynivalenol in wheat-based snacks by gas chromatography-triple quadrupole tandem mass spectrometry

Deoxynivalenol (DON) is the most frequently detected mycotoxin in cereal and cereal-based products, and a continuous monitoring of this toxin in foodstuffs is highly desirable. In this sense,a QuEChERS based extraction and gas chromatography-tandem mass spectrometry detection is proposed to determine DON in an appetizer largely consumed, the wheat-based snacks. In this study, a total of 40 samples were analyzed. The samples were divided into two groups based on the composition. Extraction was carried out with acetonitrile followed by a dispersive solid phase extraction and analyzed for DON content by gas chromatography-tandem mass spectrometry (GC-QqQ-MS/MS) method. The overall occurrence of samples with DON was 67.5%, with maximum content of 61μg/kg. In spite of its high incidence, DON concentrations found in samples were much lower than the maximum limit established in the current European legislation (500 μg/kg) for the foodstuff evaluated. Data obtained indicated a low exposure to DON through the consumption of this food commodity. Resumen: Determinación de deoxinivalenol en rosquilletas mediante cromatografía de gases acoplada a espectrometría de masas en tándem. El deoxinivalenol (DON) es la micotoxina producida por hongos del género Fusarium que con más frecuencia se detecta en cereales y productos a base de cereales. Por ello, es recomendable realizar una continua monitorización de su incidencia en los alimentos. Este trabajo propone un procedimiento analítico basado en una extracción tipo QuEChERS seguido de una cromatografía de gases acoplada a un detector de triple cuadrupolo para la determinación de DON en rosquilletas. Se analizaron un total de 40 muestras las cuales se dividieron según su composición en dos grupos. El DON fue identificado en el 67,5% de las muestras analizadas con un contenido máximo de 61 μg/kg. A pesar de su incidencia elevada, los niveles de DON hallados fueron muy inferiores a los límites máximos legislados en la actual legislación europea (500 μg/kg). Los resultados obtenidos muestran una baja exposición a DON a través del consumo de esta matriz alimentaria

Pulsed electric field (PEF) recovery of biomolecules from Chlorella : Extract efficiency, nutrient relative value, and algae morphology analysis

This study investigated the effects of pulsed electric field (PEF) (3 kV/cm, 44 pulses, 99 kJ/kg), solvent (H2O or 50 % DMSO) and time (0, 10, 20, 30, 60, 90, 120 and 180 min) on the extraction of Chlorella antioxidant biomolecules and minerals. The results showed that PEF treatment increased the biomolecules recovery. For the extraction time of 120 min, more proteins and polyphenols were obtained using water, while more chlorophyll a and b, and carotenoids were obtained using 50 % DMSO as the extraction solvent. The extracts mineral concentration (PEF vs control) were analysed including Mg, P, Ca, Fe and Zn, and the Relative Nutrient Values results indicated that Chlorella H2O-extracts could be used as a mineral source for different populations. Finally, the fluorescence and scanning electron microscopy revealed the electroporation effect of PEF

Multi-occurrence of twenty mycotoxinsin pasta and a risk assessment in the moroccan population

In the present study, the multi-occurrence of twenty (20) mycotoxins in pasta samples consumed in Morocco was assessed. For this, a modified quick, easy, cheap effective, rugged, and safe method was validated. The mycotoxins studied were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). The validated method was applied to one hundred and six (n = 106) pasta samples purchased from several areas in the country. The analytical results showed that 99 out of 106 total samples (93.4%) were contaminated with at least one mycotoxin. Nine mycotoxins (Aflatoxin B1, Enniatin B, Enniatin B1, Enniatin A1, Zearalenone, Deoxynivalenol, 3-Acetyl-Deoxynivalenol, T-2, and HT-2 toxins) were present in the pasta samples. Enniatin B and Enniatin B1 were the predominant mycotoxins. The Zearalenone, Deoxynivalenol, HT-2, and T-2 toxins were present in 51.8%, 43.5%, 34.9%, and 16% of samples, respectively. Aflatoxin B1 was detected in only 2 samples. Risk exposure assessment concluded that mycotoxin levels found in pasta do not pose a significant human health risk for the Moroccan population. This is the first paper drafted on the multi-occurrence of mycotoxins in pasta from this countr

Evaluation of Pulsed Electric Field-Assisted Extraction on the Microstructure and Recovery of Nutrients and Bioactive Compounds from Mushroom (Agaricus bisporus)

Pulsed electric field (PEF) is a sustainable innovative technology that allows for the recovery of nutrients and bioactive compounds from vegetable matrices. A. bisporus was chosen for its nutritional value and the effect of PEF pretreatment was evaluated using different conditions of electric field (2-3 kV/cm), specific energy (50-200 kJ/kg) and extraction time (0-6 h) to obtain the best conditions for nutrient and bioactive compound extraction. Spectrophotometric methods were used to evaluate the different compounds, along with an analysis of mineral content by inductively coupled plasma mass spectrometry (ICP-MS) and the surface was evaluated using scanning electron microscopy (SEM). In addition, the results were compared with those obtained by conventional extraction (under constant shaking without PEF pretreatment). After evaluating the extractions, the best extraction conditions were 2.5 kV/cm, 50 kJ/kg and 6 h which showed that PEF extraction increased the recovery of total phenolic compounds in 96.86%, carbohydrates in 105.28%, proteins in 11.29%, and minerals such as P, Mg, Fe and Se. These results indicate that PEF pretreatment is a promising sustainable technology to improve the extraction of compounds and minerals from mushrooms showing microporation on the surface, positioning them as a source of compounds of great nutritional interest

Nutritional and bioactive oils from salmon (Salmo salar) side streams obtained by Soxhlet and optimized microwave-assisted extraction

The efficiency of the microwave-assisted extraction (MAE) technique on recovering nutritional and bioactive oils from salmon (Salmo salar) side streams was evaluated and compared to Soxhlet extraction. The response surface methodology (RSM) coupled with a central composite rotatable design was used to optimize time, microwave power, and solid/liquid ratio of the MAE process in terms of oil yield. The optimal MAE conditions were 14.6 min, 291.9 W, 80.1 g/L for backbones, 10.8 min, 50.0 W, 80.0 g/L for heads, and 14.3 min, 960.6 W, 99.5 g/L for viscera, which resulted in a recovery of 69% of the total lipid content for backbones and heads and 92% for viscera. The oils obtained under optimal MAE conditions showed a healthy lipid profile as well as cytotoxic, antioxidant, anti-inflammatory, or antimicrobial properties. These results highlight that oils from underutilized salmon by-products could be exploited by different industrial sectors under the circular economy approach.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020). To FCT for the contracts of J. Pinela (CEECIND/01011/2018) and L. Barros (through the institutional scientific employment program-contract). This work was funded by the European Regional Development Fund (ERDF) through the Competitiveness and Internationalization Operational Program (POCI), within the scope of project HealthyPETFOOD (POCI-01-0247-FEDER-047073), and by BBI-JU through the H2020 Project AQUABIOPRO-FIT “Aquaculture and agriculture biomass side streams proteins and bioactives for feed, fitness, and health promoting nutritional supplements” (Grant number 790956).info:eu-repo/semantics/publishedVersio

Development and implementation of an "escape room" gamification methodology as an innovative teaching tool for students of the degree in Gastronomic Sciences

[EN] Various international organisations have emphasized the importance of establishing both health-based as well as adequate sanitary food guidelines to avoid possible food contamination and potential danger due to improper handling of food. Thus, students of gastronomic sciences must be able to detect hazards (chemical and biological) in the consideration and preparation of menus. The growing interest of students in this field of study also requires a more dynamic and practical method of teaching which can be carried out in seminars. Multidisciplinary case studies oriented towards hazard detection and nutritional objectives are proposed. Due to the current Covid-19 health crisis, hosting and participication in these seminars has been adversely affected. The creation of a virtual reality learning resource in which to interact while reducing risk could be a very interesting alternative. The aim of this resource was to create a task using a gamification approach ("escape room") in a virtual laboratory, in which to pass related tests of both a nutritional and food safety background, and thus save their patient from a specific ailment. As indicated by the high percentage of correct answers in the activity this "escape room" resource was shown to positively reinforce students´ knowledge.[ES] Los diferentes organismos internacionales hacen hincapié en la necesidad de establecer pautas dietéticas saludables y seguras, evitando posibles intoxicaciones por manipulación incorrecta en restauración o alimentos preparados para reducir el posible peligro. Así el estudiante de ciencias gastronómicas debe ser capaz de detectar peligros (químicos y biológicos) en la elaboración de menús. El creciente interés de los estudiantes en este campo de estudio, requiere también de una docencia más dinámica y práctica que puede llevarse a cabo en los seminarios. Se proponen casos de estudio multidisciplinar orientados a la detección de peligros y al cumplimiento de objetivos nutricionales. Debido a la situación actual de pandemia, la asistencia a estos seminarios ha sido difícil. La creación de un recurso didáctico de realidad virtual en el que interactuar pero sin poner en riesgo su salud sería una alternativa muy interesante. El objetivo de este recurso fue crear una tarea utilizando un enfoque de gamificación ("escape room") en un laboratorio virtual, en el que pasar pruebas relacionadas, tanto nutricionales como de seguridad alimentaria, y así salvar a su paciente de una dolencia específica. El “escape room” reforzó positivamente los conocimientos del estudiante ante el gran porcentaje de aciertos en la actividad.Este trabajo ha contado con el apoyo del Vicerectorat d’Ocupació i Programes Formatius de la Universitat de València – a través del proyecto concedido en el marco de las “Ajudes per al Desenvolupament de Projectes d’Innovació Educativa per al curs 2021-2022” con nombre “Sherlock-Salud: Utilización de metodología de escape room para casos de estudio de Nutrición y Seguridad Alimentaria” (NOU-PID, UV-SFPIE_PID-1640423) así como el proyecto AQUABIOPRO-FIT “Aquaculture and agriculture biomass side stream proteins and bioactives for feed, fitness and health promoting nutritional supplements” (Grant Agreement no. 790956) financiado por la Comisión Europea a través del programa H2020-BBI-JU.Barba Orellana, F.; Martí Quijal, F.; Pallarés Barrachina, N.; Juan García, C.; Berrada Ramdani, H. (2022). Desarrollo e implementación de una metodología de gamificación "escape room" como herramienta docente innovadora para los estudiantes del grado en Ciencias Gastronómicas. En In-Red 2022 - VIII Congreso Nacional de Innovación Educativa y Docencia en Red. Editorial Universitat Politècnica de València. 231-238. https://doi.org/10.4995/INRED2022.2022.1585323123

Sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) head oils recovered by microwave-assisted extraction: nutritional quality and biological properties

Microwave-assisted extraction (MAE) and Soxhlet extraction (SE) were used to obtain oil from European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) heads. The MAE technique allowed the recovery of more than 50% of the total lipid con- tent for both fish by-products in less than 11 min extraction. Based on their fatty acid composition, all fish head oils presented a healthy lipid profile and were found to be a good source of docosahexaenoic acid (DHA, 11–14%). Different lipid quality indices also revealed their cardiovascular protective potential. Oils obtained by MAE showed higher antibacterial and antifungal effects against food pathogens than those extracted by SE. Cellular antioxidant activity (29–35% oxidation inhibition) and anti-inflammatory poten- tial via NO production inhibition (IC50 = 14–21 μg/mL) were evaluated using murine macrophages cells (RAW 264.7). The highest cytotoxic effect (GI50 = 38–46 μg/mL) of fish head oils was observed against breast cancer cells (MCF-7). These results showed that sea bass and gilthead sea bream heads could be exploited for the production of oil with nu- tritional and bioactive properties in line with circular bioeconomy concepts.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020). To FCT for the contracts of J. Pinela (CEECIND/01011/2018) and L. Barros (institutional scientific employment program-contract). Work funded by the European Regional Development Fund (ERDF) through the Competitiveness and Internationalization Operational Program (POCI), within the scope of project HealthyPETFOOD (POCI-01-0247-FEDER- 047073), and by BBI-JU through the H2020 Project AQUABIOPRO-FIT “Aquaculture and agriculture biomass side streams proteins and bioactives for feed, fitness, and health promoting nutritional supplements” (Grant number 790956)info:eu-repo/semantics/publishedVersio

Quantitative determination of trichothecenes in breadsticks by gas chromatography-triple quadrupole tandem mass spectrometry

Breadsticks are pencil-sized sticks of dry bread widely consumed as a pre-meal appetiser. They are basically wheat-based snacks, which makes them a good matrix to evaluate mycotoxin contamination, since wheat is very susceptible to fungal attack. In this sense, the fast, selective and sensitive gas chromatography-triple quadrupole tandem mass spectrometry (GCQqQ- MS/MS) method proposed here allows simultaneous determination of deoxynivalenol (DON), 3-acetyldeoxynivalenol, fusarenon-X, diacetoxyscirpenol, nivalenol, neosolaniol, HT-2 and T-2 toxin in breadsticks after QuEChERS extraction and clean-up. The performance of the method was assessed with respect to European Commission Regulations by studying the selectivity and specificity, limit of detection (LOD), limit of quantitation (LOQ), linearity, matrix effect, accuracy, precision and trueness. Satisfactory results in terms of validation parameters were obtained for all selected mycotoxins (recovery range of 70110%, RSD 1). The trueness of the method was supported by using certified reference material (DON 1062 ± 110 μg kg1). The method was successfully used to evaluate the occurrence of the studied Fusarium toxins in 61 breadstick samples. A total of 64% of the samples showed mycotoxin contamination, DON being the most frequently detected toxin. Nonetheless, mean levels obtained were far below the maximum levels permitted by European Union legislation. An additional goal was to carry out a risk-characterisation approach to DON by comparing probable daily intake and provisional maximum tolerable daily intake (PMTDI)