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Santiago de Compostela, Spain

Dominguez-Gonzalez R.,Nutrition and Bromatology | Gonzalez Varela L.,Nutrition and Bromatology | Bermejo-Barrera P.,Nutrition and Bromatology
Talanta | Year: 2014

Gold nanoparticles are attractive as sensing materials because of their size and shape are related with their optical properties. The color change produced by the aggregation of functionalized AuNPs allows the detection of arsenic at low levels. A simple, cheap and fast analytical procedure to perform arsenic determination using functionalized gold nanoparticles (AuNPs) and VIS spectrometry as a detection technique is studied. Three different synthesis procedures to obtain the AuNPs and two different functionalization modes were studied. AuNPs functionalized with GSH-DTT-CYs-PDCA were selected as the most adequate. The correlation between the decrease in the absorbance signal and the arsenic concentration was good in the 2-20 μg l-1interval. Repeatability, expressed as average of RSD (%), obtained for the different arsenic concentrations studied was 0.6%. The average value of the analytical recovery was 99.7%. The detection and quantifications limits were 2.5 and 8.4 μg l-1 respectively. These limits are sufficient to detect World Health Organization's guideline value of 10 μg l-1. © 2013 Elsevier B.V.

Herbello-Hermelo P.,Nutrition and Bromatology | Barciela-Alonso M.D.C.,Nutrition and Bromatology | Bermejo-Barrera P.,Nutrition and Bromatology
Atomic Spectroscopy | Year: 2011

An on-line flow injection sorption preconcencentration in a knotted reactor coupled with electrothermal atomic absorption spectrometry (FI-KR-ETAAS) has been developed to determine chromium(VI) in seawater samples. The on-line complex formation between Cr(VI) and ammoniumpirrolidindithiocarbamate (APDC) was performed and the complex retained on the inner wall of the KR. Variables affecting the sorption preconcentration process, such as pH, APDC amount, load flow rate, preconcentration time, concentration, and volume of washing solution, KR length, elution volume, and interferences, were studied. The complex was eluted with 40 μL of ethanol and introduced directly into the graphite furnace. A preconcentration factor of 31 was obtained. The detection limit (3SD) was 7 ng L-1. The precision (RSD n = 11) was 4.4% at 0.2 (μg L-1. and the recovery was 99.3 ± 1.70%. The method was applied to the Cr(VI) determination in seawater samples from the Ria de Arousa Estuarine in Galicia (Northwestern Spain), resulting in Cr(VI) concentrations ranging from 0.03 - 0.09 μg L-1.

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