Mercury determination in urine samples by gold nanostructured screen-printed carbon electrodes after vortex-assisted ionic liquid dispersive liquid–liquid microextraction

A novel approach is presented to determine mercury in urine samples, employing vortex-assisted ionic liquid dispersive liquid–liquid microextraction and microvolume back-extraction to prepare samples, and screen-printed electrodes modified with gold nanoparticles for voltammetric analysis. Mercury was extracted directly from non-digested urine samples in a water-immiscible ionic liquid, being back-extracted into an acidic aqueous solution. Subsequently, it was determined using gold nanoparticle-modified screen-printed electrodes. Under optimized microextraction conditions, standard addition calibration was applied to urine samples containing 5, 10 and 15 μg L−1 of mercury. Standard addition calibration curves using standards between 0 and 20 μg L−1 gave a high level of linearity with correlation coefficients ranging from 0.990 to 0.999 (N = 5). The limit of detection was empirical and statistically evaluated, obtaining values that ranged from 0.5 to 1.5 μg L−1, and from 1.1 to 1.3 μg L−1, respectively, which are significantly lower than the threshold level established by the World Health Organization for normal mercury content in urine (i.e., 10–20 μg L−1). A certified reference material (REC-8848/Level II) was analyzed to assess method accuracy finding 87% and 3 μg L−1 as the recovery (trueness) and standard deviation values, respectively. Finally, the method was used to analyze spiked urine samples, obtaining good agreement between spiked and found concentrations (recovery ranged from 97 to 100%).

Física y Química: 1º Bachillerato

La existencia de materiales de trabajo valorados positivamente por quienes han de usarlos, contribuye a que el proceso de enseñanza y aprendizaje pueda desarrollarse de una manera más eficaz. Ésta ha sido la intención que nos ha guiado al escribir: diseñar un libro de texto de física y química que pueda ser útil a la mayor parte posible de profesores y alumnos. Para conseguir el objetivo anterior, hemos partido del convencimiento de que todo conocimiento y aprendizaje científico es la respuesta a problemas de interés, lo que nos ha llevado a plantear los contenidos y su secuenciación en base a unos cuantos grandes problemas estructurantes como: ¿Qué son y cómo se producen los cambios materiales? ¿A qué se debe la gran diversidad de sustancias existentes? ¿Cómo pueden cambiar unas sustancias en otras de propiedades diferentes?