Control de la concentración de metilmercurio en productos pesqueros para el consumo humano mediante el empleo de polímeros de impronta molecular y de nanopartículas derivatizadas / Control of the methylmercury concentration in fish and seafood products for human consumption using molecularly imprinted polymers (MIPs) and derivatized nanoparticles

Objetivo: Desarrollar un polímero de impronta molecular para la determinación de metilmercurio en muestras de alimentos de origen marino. Material y métodos: Se sintetizó un polímero de impronta molecular (MIP) que emplea fenobarbital como ligando no vinilado para unirse al metilmercurio. Se utilizó la técnica de polimerización por precipitación. El MIP sintetizado fue empleado para funcionalizar nanopartículas magnéticas con el fin de mejorar el proceso de extracción del metilmercurio de las muestras. Resultados: El MIP con fenobarbital fue aplicado para la determinación de la concentración de metilmercurio en dos materiales de referencia de concentración certificada para el análisis de muestras de alimentos marinos (BCR-463, tejido de atún, y TORT-2, hepatopáncreas de langosta). Los valores de concentración experimentales obtenidos fueron de 3,04±0,16 μg/g y 0,152±0,013 μg/g respectivamente, coincidiendo con los valores certificados de forma estadísticamente significativa (test t, 95% confianza). Conclusiones: Se ha sintetizado un MIP para la determinación de la concentración de metilmercurio a bajas concentraciones en muestras de alimentos de origen marino (AU)

Objective: The development of a molecularly imprinted polymer support for methylmercury determination in fish and seafood samples. Materials and methods: A molecularly imprinted polymer was synthesized using the precipitation technique and phenobarbital as a non-vinylated ligand for binding methylmercury. The synthesized MIP was used for the functionalization of magnetic nanoparticles in order to improve the process of methylmercury extraction from the samples. Results: The MIP prepared with phenobarbital was applied to the determination of methylmercury concentration in two certified reference materials used for fish and seafood samples analysis (BCR-463, tuna fish, and TORT-2, lobster hepatopancreas). The experimental values (3.04±0.16 μg/g and 0.152±0.013 μg/g respectively) and the certified values showed no statistically significant difference (t test, 95% confidence level). Conclusions: We have synthesized a MIP for determining methylmercury in fish and seafood samples at low concentrations (AU)

Comparison of two lab-made spray chambers based on MSIS™ for simultaneous metal determination using vapor generation-inductively coupled plasma optical emission spectroscopy.

The objective of this study is to evaluate the performance of two lab-made systems based on the Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An univariate procedure was used to select the optimized working conditions (Ar flow, sample, reductant and waste flows, and reagent concentrations). Optimum conditions for working with modified MSIS were: nitric acid concentration 0.35 M, 8-hydroxyquinoline concentration: 40 mg L(-1), sodium borohydride concentration: 1.75% (w/v)+0.4% (w/v) NaOH, argon purge flow to sweep the vapors to the torch: 1.2 L min(-1), sample flow and sodium borohydride flows: 2.3 L min(-1); waste flow: 7.7 mL min(-1). For the optimum working conditions for lab-made MSIS in dual mode the concentration of 8-hydroxyquinoline was 225 mg L(-1), the Ar purge flow was 0.75 L min(-1), and the conventional nebulization flow was 2.3 L min(-1). The sensitivity obtained was higher using the lab-made MSIS than using the lab-made modified MSIS or a forced outlet gas-liquid separator. The limits of detection were better for Au, Cd, Sn than those obtained using conventional nebulization; the measurements were precise (RSDs≤5% in dual mode) and a good accuracy was obtained in the determination of Cd, Cu, Ni and Zn in a wastewater reference material using aqueous calibration and the lab-made MSIS in dual mode.

Development of a microalgal PAM test method for Cu(II) in waters: comparison of using spectrofluorometry.

Test methods are needed to monitor Cu concentrations in reservoirs and water supplies. Dictyosphaerium chlorelloides (Chlorophyta) cells were immobilized in a silicate sol-gel and the toxic effects of Cu(II) were examined using different techniques: fluorescence measurements (using a spectrofluorometer with an optic fiber coupled to a flow cell or a 96-well-plate reader) or by Pulse Amplitude Modulation (PAM) parameters using a portable instrument and the pulse saturation method. Fm' and qN were the most sensitive indicator parameters when performing Cu analysis in water. D. chlorelloides PAM biosensor presented a detection limit of 0.6 mg l(-1) for Cu(II), within the limits to establish if Cu concentrations exceeded regulatory levels. Moreover, a 1.9 mg Cu l(-1) (30 microM) resistant strain of the D. chlorelloides microalgae was produced in order to obtain more selectivity on the metal determination.

Phthalates determination in physiological saline solutions by HPLC-ES-MS.

Phthalates are a group of chemical compounds with increasing interest from the analytical point of view. The risks for human health associated with some of these compounds have unleashed the necessity to develop analytical methods with great sensitivity that allow us to detect their presence at trace levels in order to assure protection for the population. A simple and rapid method for determining a group of phthalate esters in aqueous samples was developed. The method was based on high-performance liquid chromatography-(electrospray)-mass spectrometry (HPLC-ES-MS), working in positive ionisation (PI) mode. A gradient elution was performed with acetonitrile-ultrapure water starting from 5 to 75% acetonitrile in 5 min followed by isocratic elution during 5 min. Standard calibration curves were linear for all the analytes over the concentration range 10-500 ng mL(-1). The LOD values found for DMP, DEP, BBP and DBP were 0.8, 3.4, 0.6 and 1.2 ng mL(-1) respectively. The relative standard deviation ranged from 0.8 to 1.7%, which indicated good method precision. The proposed analytical method has been applied to the analysis of commercial physiological saline solutions in order to check the presence of phthalates and to determine their concentration.