RESUMEN
For environmental safety, it is important to establish a simple, rapid, and sensitive method for emerging pollutants. Here, a dispersive solid-phase extraction (d-SPE) method based on an iron-based metal-organic framework (Fe-MIL-88-NH2) combined with high-performance liquid chromatography (HPLC) was developed for tetrabromobisphenol A (TBBPA) in water samples. Fe-MIL-88-NH2 was synthesized using a solvothermal method and completely characterized. Fe-MIL-88-NH2 had good water stability and gave a maximum adsorption capacity of 40.97 mg g-1 for TBBPA. The adsorption of TBBPA on Fe-MIL-88-NH2 followed Langmuir adsorption models and a pseudo-second-order kinetic model. The bromine ion and the hydroxyl group of TBBPA could form strong hydrogen bond interactions with the amino protons around the cavity of Fe-MIL-88-NH2, which was in accord with the molecular simulation calculations. Furthermore, several important d-SPE parameters were optimized, such as the amount of materials, extraction time, pH, ionic strength, elution solvent type, and volume. The established method showed good linearity in the concentration range of 0.005-100 µg g-1 (r2 ≥ 0.9996). This method's limits of detection (LOD) and quantification (LOQ) were 0.001 µg g-1 and 0.005 µg g-1, respectively. The recoveries in spiked water samples ranged from 87.5% to 104.9%. The proposed method was applied successfully to detect TBBPA in environmental water samples.
Asunto(s)
Estructuras Metalorgánicas , Estructuras Metalorgánicas/química , Adsorción , Hierro/química , Extracción en Fase Sólida/métodos , AguaRESUMEN
A novel magnetic metal-organic frameworks (Fe3O4@UiO-66-SH) was successfully prepared by coating Fe3O4 nanospheres with sulfur-functionalized UiO-66. The Fe3O4@UiO-66-SH possesses both the magnetic properties of Fe3O4 and the diverse properties of metal-organic framework (MOF) in one material, which has the superiority of high surface area, easy-operation and strong adsorb ability with mercury, is used for the magnetic solid-phase extraction of methylmercury (MeHg+) and inorganic mercury (Hg2+) in water and fish samples. The analyzes were conducted by high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The different pretreatment conditions influencing the extraction recoveries of Hg2+ and MeHg+, including adsorbent amount, pH, extraction time, elution solvent, elution volume, desorption time, co-existing ions and dissolved organic materials were investigated. Under the optimized conditions, the limits of detection (LODs) of Hg2+ and MeHg+ for water samples were 1.4 and 2.6 ng L-1, and the limits of quantification (LOQs) of Hg2+ and MeHg+ for water samples were 4.7 and 8.7 ng L-1. The enrichment factors (EFs) were 45.7 and 47.6 fold for Hg2+ and MeHg+, respectively. The accuracy of the proposed method was demonstrated by analyzing the certified reference material of fish tissue (GBW10029) and by determining the analyte content in spiked water and fish samples. The determined values were in good agreement with the certified values and the recoveries for the spiked samples were in the range of 84.5-96.8%.
Asunto(s)
Técnicas de Química Analítica/métodos , Peces , Mercurio , Estructuras Metalorgánicas , Compuestos de Metilmercurio , Extracción en Fase Sólida , Agua , Animales , Cromatografía Líquida de Alta Presión , Fenómenos Magnéticos , Mercurio/análisis , Mercurio/aislamiento & purificación , Estructuras Metalorgánicas/química , Compuestos de Metilmercurio/análisis , Compuestos de Metilmercurio/aislamiento & purificación , Azufre/química , Agua/químicaRESUMEN
A method for simultaneous determination of arsanilic, nitarsone and roxarsone (ROX) residues in foods of animal origin was developed by accelerated solvent extraction-liquid chromatography-atomic fluorescence spectrometry (ASE-LC-AFS). The ultrasound centrifugation extraction and accelerated solvent extraction were compared, and the accelerated solvent extraction conditions, namely the proportion of the extraction solvent, the extraction temperature, extraction time and extraction times, were optimized. The operating conditions of LC-AFS and the mobile phase were optimized. Under the optimal conditions, the calibration curves for ASA , NIT and ROX were linear over the concentration range of 0-2.0 mg x L(-1) and their correlation coefficients were 0.999 2-0.999 8. The detection limits of ASA, NIT and ROX were 2.4, 7.4 and 4.1 microg x L(-1) respectively. The average recoveries of ASA, NIT and ROX from two samples spiked at three levels of 0.5, 2, 5 mg x kg(-1) were in the ranges of 87.1%-93.2%, 85.2%-93.9%, and 84.2%-93.7% with RSDs of 1.4%-4.6%, 1.2%-4.2%, and 1.1%-4.5%, respectively. This method possesses the merits of convenience and good repeatability, and is a feasible method for analysis of ASA, NIT and ROX in foods of animal origin.
Asunto(s)
Ácido Arsanílico/análisis , Arsenicales/análisis , Cromatografía Liquida , Carne/análisis , Roxarsona/análisis , Animales , Espectrometría de Fluorescencia , TemperaturaRESUMEN
Flow injection-hydride generation-atomic fluorescence spectrometry was a widely used method in the industries of health, environmental, geological and metallurgical fields for the merit of high sensitivity, wide measurement range and fast analytical speed. However, optimization of this method was too difficult as there exist so many parameters affecting the sensitivity and broadening. Generally, the optimal conditions were sought through several experiments. The present paper proposed a mathematical model between the parameters and sensitivity/broadening coefficients using the law of conservation of mass according to the characteristics of hydride chemical reaction and the composition of the system, which was proved to be accurate as comparing the theoretical simulation and experimental results through the test of arsanilic acid standard solution. Finally, this paper has put a relation map between the parameters and sensitivity/broadening coefficients, and summarized that GLS volume, carrier solution flow rate and sample loop volume were the most factors affecting sensitivity and broadening coefficients. Optimizing these three factors with this relation map, the relative sensitivity was advanced by 2.9 times and relative broadening was reduced by 0.76 times. This model can provide a theoretical guidance for the optimization of the experimental conditions.
Asunto(s)
Modelos Teóricos , Espectrometría de Fluorescencia , Espectrofotometría AtómicaRESUMEN
Concentrations of As, Hg, Pb, Cd in soils and herbal medicine samples from cultivated regions of Anguo City in Hebei Province were analyzed and assessed, and the bioconcentration factors of different herbal medicines were studied and discussed as well. The results showed that the average contents of As, Hg, Pb, Cd in soils from herbal medicine cultivated regions were 12.9, 0.036, 15.6, 0.118 mg x kg(-1), respectively. Concentrations of heavy metals in soils were lower than class II of the soil environmental quality standard. When local soil background values of heavy metals were used as assessment standard, among the 16 cultivated regions the percentage of As, Hg, Ph, Cd belonging to lightly pollution class were 18.75%, 43.75%, 0%, 100%, respectively based on the single pollution index. And the Nemerow index results were between 1 and 2, which suggested the soils were at slight pollution level. However, when quality standard class II was used, both the single pollution index and Nemerow index did not exceed 0.7, which means that soils investigated were generally safe for cultivation of Chinese herbal medicines. The assessment of heavy metals in herbal medicines showed that the pollution indices of most herbal samples (< 95%) were lower then 1. Cd bioconcentration factors of Aster tataricus L. and Anemarrhena asphodeloides Bunge, Hg bioconcentration factors of Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f. and Glehnia littoralis F. Schmidt ex Miq. were above 1. Therefore, the accumulation characteristic of heavy metals in Chinese herbal medicines should be fully concerned when GAP base soil quality assessment was taken.