Development of a dispersive liquid-liquid microextraction coupled with magnetic dispersive microsolid phase extraction for determination of triazines in wastewater samples.

The combination of two microextraction techniques (dispersive liquid-liquid microextraction [DLLME] and magnetic dispersive microsolid phase extraction [MDMSPE]) was developed and reported for atrazine and simazine preconcentration from wastewater samples. The proposal methodology involved the use of magnetite supports functionalized with different alkyl or phenyl groups. The magnetic adsorbents were synthesized by the solvothermal method assisted by microwave, characterized, and used in the sample preconcentration of atrazine and simazine. The method validation included parameters such as the wastewater matrix effect, repeatability, and recovery. The analyte separation and quantification were performed by high-performance liquid chromatography with ultraviolet detection (HPLC-DAD). Parameters, such as the polarity and mass of magnetic solids and pH, were evaluated to provide better extraction performance. The highest recoveries (> 95%) were obtained with 50 mg of the phenyl group support (CS2) at pH 5, using 5 mL of the sample and carbon tetrachloride and methanol, as extraction and dispersive solvents, respectively. The lowest limits of detection (LOD) achieved were 13.16 and 13.86 ng L-1, and the limits of quantification (LOQ) were 43.89 and 46.19 ng L-1 for simazine and atrazine, respectively, with repeatability (expressed as %RSD) below 5% in all cases. The developed method is simple, easy, and low cost for the analysis of two herbicides potentially dangerous for environmental and human health. Graphical abstract.

Lixiviación selectiva de arsénico y otros elementos de material sedimentario arrastrado por aguas subterráneas en zimapán Hidalgo México / Selective lixivation of arsenic and other elements in sedimentary material carried by underground waters in zimapan Hidalgo México

Se llevó a cabo la caracterización física y química de los sedimentos del distribuidor general de agua potable de la ciudad de Zimapán, Hidalgo, México, con el fin de comprobar su relación con el origen del suministro. Los análisis realizados a lo largo de 10 meses revelaron contenidos elevados de SiO2, Fe, Al, As, Ca y Mn. Ante la ausencia de normativa específica para determinar el índice de peligrosidad de estas muestras, se han llevado a cabo estudios de extracciones secuenciales mediante los esquemas de Tessier y el BCR, que demuestran que los componentes más tóxicos se lixivian en las primeras porciones del sistema, y por tanto fácilmente. La comparación con los resultados de las muestras de agua indica la existencia de procesos de lixiviación, lo que es especialmente grave en el caso del As, ya que llega a alcanzar niveles del 11 por ciento