www.futurenviro.es | Abril-Mayo April-May 2022 59 Contaminantes Emergentes. Microplásticos | Emerging Pollutants. Microplastics mediante TD/MS, obteniendo directamente concentración (µg/L). En concreto, los plásticos retenidos en el filtro (>0,3 µm) son calentados a 320ºC para su degradación térmica y rotura de polímeros en monómeros o dímeros, siendo estos compuestos volátiles retenidos en una trampa fría a -20ºC, la cual posteriormente es calentada a 320 ºC en forma balística, tras lo cual los compuestos son separados y secuenciados mediante CG/MS. Dado que cada plástico ofrece un perfil cromatográfico distinto, eligiendo iones característicos a los tiempos de retención de los compuestos seleccionados, se posibilita caracterizar y cuantificar los distintos tipos de plásticos (Figura 2). Resultados y conclusiones Se analizaron los siguientes plásticos: polietileno (PE), poliestireno (PS), cloruro de polivinilo (PVC), poliamida (PA), tereftalato de polietileno (PET) y poliuretano (PU), con límites de cuantificación para la técnica empleada de 100 µg/L para PE, y de 5 µg/L para el resto de plásticos analizados. Los resultados obtenidos demuestran una no detectable o baja concentración en aguas de los MP, sólo datando la presencia de PVC (6 a 7 µg/L) y PS (8 a 5 µg/L). Estos MP podrían tener su origen en una mínima erosión interna de las canalizaciones de transporte de las aguas de grifo. INVESTIGACIONES Y RESULTADOS OBTENIDOS POR LABAQUA Tomas de muestras Debido a la baja concentración de MP que se han encontrado hasta la fecha en las aguas de consumo, se optó por realizar un muestreo de 4 litros recogidos en envase de vidrio. Técnicas analíticas Se ha empleado la termo extracción-desorción seguida de cromatografía de gases-espectrometría de masas (TED-GC-MS) sometiendo la muestra a un programa de temperatura atrapando en atmósfera inerte los gases generados sobre adsorbentes en fase sólida. Los productos de descomposición se han derivado posteriormente a un sistema de cromatografía de gases-masas (GC-MS) (Dümichen et al., 2015; Dümichen et al., 2019) para separar compuestos según su tamaño y polaridad, y ser analizados mediante un detector selectivo de masas. De estemodo se consiguen cromatogramas y espectros demasas para los productos generados durante la pirólisis, cuya comparación con datos contrastados, permite identificar los compuestos en los que se han degradado los polímeros plásticos originales de forma sencilla y simple. Resultados y conclusiones En un estudio de LABAQUA en 2021 se analizaron las aguas brutas de entrada de una ETAP ubicada en el sur de España, agua de uno de Since each plastic has a different chromatographic profile, it is possible to characterize and quantify the different types of plastics by selecting ions that are associated to the retention times of the selected compounds (Figure 2). Results and conclusions The following plastics were analysed: polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), polyethylene terephthalate (PET) and polyurethane (PU), with quantification limits for the technique implemented of 100 µg/L for PE, and 5 µg/L for the remaining plastics analysed. The results obtained show an undetectable or low concentration of MP in water, with only the presence of PVC (6 to 7 µg/L) and PS (8 to 5 µg/L) being observed. These MP could have their origin in a minimal internal erosion of the tap water conveyance pipes. RESEARCH AND RESULTS OBTAINED BY LABAQUA Sampling Due to the low concentration of MP found to date in drinking water, it was decided to take samples of 4 litres collected in glass containers. Analytical techniques Thermo extraction-desorption was implemented followed by gas chromatography mass spectrometry (TED-GC-MS). Then, the sample was subjected to a temperature program to trap the gases generated on solid-phase adsorbents in an inert atmosphere. The decomposition products were subsequently sent to a gas chromatography mass spectrometry (GC-MS) system (Dümichen et al., 2015; Dümichen et al., 2019) to separate compounds according to size and polarity, after being analysed using a mass selective detector. In this way, chromatograms and mass spectrums were obtained for the products generated during pyrolysis and comparison of these with verified data enabled identification of the compounds into which the original plastic polymers have been degraded in a simple and straightforward manner. Results and conclusions In a study conducted by LABAQUA in 2021, the inlet raw water of a DWTP in southern Spain, water from one of its settling tanks and treated water leaving the plant were analysed. The polymers identified were: Polyethylene (PE), Polystyrene (PS), Polypropylene (PP), Polyamide (PA), Polyethylene terephthalate (PET) and Polyvinyl chloride (PVC). It was found that in the majority of cases the concentrations were below the quantification limits of the method, even in the raw water fed into the plant. The most relevant conclusions of this study were that very low quantities of Polyamide (30 g/L) and Polyethylene (30 g/L) were found in the settling tank studied at the DWTP. This was probably the result of slight flaking of the tank walls, meaning that the source of MP in the water would be internal to the DWTP itself rather than external. Moreover, MP were not detected in the product drinking water at the outlet of the DWTP. RESEARCH AND RESULTS OBTAINED BY AIGÜES DE BARCELONA Studies were carried out on surface water from the Llobregat River, water taken from different points of the drinking water Figura 2: Cromatogramas para diferentes plásticos y algodón como blanco. Figure 2: Chromatograms for different plastics and cotton as a control material.
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