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ABSTRACT: Molecular imprinting technology has been employed for the first time to prepare a specifically affinity chromatographic stationary phase for speciation purposes. Tributyltin has been chosen as the template molecule and the non-covalent approach has been applied. Three different polymerization methods have been evaluated: (i) a composite material, (ii) a polymer prepared via-Iniferter grafting; (iii) an emulsion polymer. Columns packed with different polymers have been evaluated by liquid chromatography (LC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The chromatographic conditions as well as the analytical characteristics of the developed method are discussed in this paper. Our findings have shown formation of specific cavities in the grafted Iniferter as well as in the emulsion polymers with the latter achieving resolution of four organotin compounds. Detection limits are similar to those obtained with commercial, but not specific, stationary phases (6 pg for monobutyltin, MBT; 10 pg for both tributyltin, TBT, and triphenyltin, TPhT; and 20 pg for dibutyltin, DBT). The main advantage of this proposed stationary phase is that good recovery is obtained for all species, including MBT. Baseline resolution for TBT and TPhT has also been obtained. The high selectivity of this column prevents matrix interferences. The method has been validated by analyzing two biota reference materials (ERM-CE477 mussel tissue and T-38 oyster tissue).
Journal of chromatography. A 05/2010; 1217(20):3400-7. · 4.19 Impact Factor
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ABSTRACT: Organotin compounds and their degradation products enter the environment mainly as a result of their use as biocides and antifouling paints. Analysis of these compounds in environmental samples has to be very sensitive and selective so that their concentrations corresponding to the low environmental target values can also be detected. Generally, analysis of a complex matrix leads to high interferences during the different process steps; clean-up procedures are recommended to overcome this problem. For the past many years, solid phase extraction by employing imprinted materials has been extensively used for many organic substances that are used for pre-concentration and clean-up purposes with excellent results. Here, we present three different imprinted polymers prepared via bulk, precipitation, and emulsion polymerization methods that use similar compositions. The synthesized polymer particles were characterized morphologically by employing scanning electron microscopy and Brunauer-Emmett-Teller analysis. Binding properties were calculated using the Langmuir-Freundlich isotherm. Depending on the properties of the materials, different analytical applications for complex matrices are proposed. These applications are mainly used on tributyltin and its degradation products for environmental analysis.
Journal of Environmental Management 11/2008; 90 Suppl 1:S69-76. · 3.24 Impact Factor
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ABSTRACT: RESUMEN. Se realizaron investigaciones acerca de la remediación de aguas residuales para prevenir daños, tanto de las reservas de aguas subterráneas como superficiales. Con este propósito, las tierras de diatomeas, un barato, disponible y no contaminante material, fue ensayado para la retención de contaminantes per-sistentes, tales como los metales pesados (cadmio) y pesticidas (antracita y cloropirifos). Esto ha sido utilizado en la prevención de la contaminación de aguas subterráneas debido a su gran movilidad reportada y a la irrigación y limpieza de suelos destinados a la agricultura. Variables tales como profundidad, espesor, etc. de los suelos quedaron cuidadosamente establecidos para simular una explotación casi real de suelos potencialmente contaminados. Los resultados preliminares presenta-dos aquí muestran porcentajes de retención de cadmio mayores del 75 % y del 50 % para la antracita. Estos enfatizan el potencial uso como limpiador y remediador de las tierras de diatomea para contaminantes persistentes, tales como los metales pe-sados y los pesticidas, en particular, los utilizados en este estudio. La adsorción por las tierras de diatomeas es válida para todos los suelos ensayados. Luego, existe la posibilidad de prevenir la contaminación por cadmio en aguas subterráneas por de-posición de una capa de las tierras de diatomeas bajo la superficie de los suelos. ABSTRACT. Research effort dealing with the remediation of leaching waters polluted to prevent further damage of surface and ground water reserves are needed. For this purpose, diatomaceous earth, an inexpensive, available and no pollutant material, has been tested for retention of persistent pollutants, such as heavy metals (cadmium) and pesticides (atrazina and chlorpirifos). It has been used as underground water pollution prevention because of their high mobility reported, and for cleaning irrigation waters of a soil destined to agriculture purposes. There are parameters, such as depth, thickness, etc. that should be carefully established in order to respect the exploitation use of the potential pol-luted soil. The results obtained shown percentages retention for cadmium higher than 75 %, and 50 % for atrazina. This emphasises the potential of diatomaceous earth with remediation and cleaning purposes for persistent pollutants, such as heavy metals and pesticides used for this purpose. This DE adsorption is valid for all soils tested. The possibility to prevent cadmium underground water pollution by placing a diatomite earth layer under the surface of the soils exists then.
Revista CENIC Ciencias Químicas. 01/2007; 38.
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ABSTRACT: There is a high interest in speciation of organotin compounds (OTCs) in biota and marine sediment samples, due to their influence in the transmission of the contamination in the trophic chain. Sample treatment is still the most "compromising" step of speciation analysis. Extraction methods are in general time-consuming due to long extraction times and several analytical steps involved. In addition, in most cases there are problems of low recovery, especially for MBT. These drawbacks, added to the high matrix effects generally present in biota samples, make the sample treatment for organotin analysis a serious challenge for environmental issues. Here we present a novel, fast and efficient two steps method for organotin speciation in mussel and oyster tissue as well as in marine sediments. The first step based on the use of ultrasonic probe extraction for species leaching allowed us to quantitatively extract these compounds in a few minutes. Matrix interferences drastically decreased by applying a clean-up step based on the use of an imprinted polymer especially designed for tributyltin (TBT). This procedure increased accuracy and precision of the GC-FPD analysis and improving the limit of detection, Besides, this new method prevents the use of standard addition calibration method, which is mandatory without the clean-up step. The optimization and validation has been performed by using three reference materials: mussel tissue CRM-477, oyster candidate T-38 and sediment PACS-2.
Journal of Chromatography 06/2006; 1114(1):82-8. · 4.53 Impact Factor
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ABSTRACT: The covalent imprinting approach has for the first time been successfully applied for the synthesis of an imprinted polymer able to recognize organotin species. The synthesis has been accomplished by co-polymerization of the complex Bu(2)SnO-m-vinylbenzoin as the imprinting template plus co-monomer sodium methacrylate, and ethylene glycol dimethacrylate as cross-linker. The imprinting effect has been evidenced within the narrow pH range 2.5< pH< 3.5. At lower pH values, the imprinting effect is prevented by the exclusive existence of non-specific interactions, whereas pH>3.5 provokes a strong rebind of the template in both imprinted and non-imprinted polymers. This pH dependency can be explained as a selective chemical modification which reduces bind diversity following a model based on enolization by protonation of the specific cavities. Characterization of the adsorption isotherms showed good agreement with the Langmuir-Freundlich (LF) model, presenting quite homogeneous binding sites for a bulk material and high capacity in the imprinting pH range. In addition, the affinity spectrum (AS) method has been represented showing the typical profiles of LF isotherm for both sub-saturation and saturation levels, being in general agreement with the encountered values for fitting coefficients. The covalent molecular imprinted polymer has been successfully evaluated in a SPE process for further OTC determination in the certified mussel tissue (CRM 477).
The Analyst 02/2006; 131(1):98-105. · 4.23 Impact Factor
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ABSTRACT: Two procedures have been investigated for the quantification of the different forms of mercury in food. A two-stage procedure has been developed to determine firstly total inorganic and organometallic species, and then the full separation of all organomercury species. The procedure involves solubilisation of the samples using alkaline extractions or enzymolysis, followed by the extraction of organic mercury in an organic solvent, preferably a mixture of dichloromethane and hexane (3:2). For the total organic mercury determination, the organic extract is analysed for "total" mercury after nitric acid/peroxide digestion, evaporation of the solvent and detection by cold vapour-atomic fluorescence spectrometry. Full organomercury speciation requires a clean-up step before analysis of the final extract in dichloromethane by gas chromatography coupled to a pyrolyser and an atomic fluorescence detector (GC-pyro-AFS). A detection limit of 6 ng l-1, and reproducibility of 2% was achieved for the CV-AFS method; GC-pyro-AFS yielded 200 ng l-1 and 5% for detection limit and coefficient of variation, respectively. Both procedures were validated with the use of various certified reference materials over a wide range of mercury concentrations, and by spiking experiments. The validated methods were tested successfully on a wide range of commercially available food samples.
The Analyst 09/2002; 127(8):1108-14. · 4.23 Impact Factor
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ABSTRACT: An analytical method for Cd analysis in solid samples which combines the ultrasonic slurry formation with cold vapour generation and atomic absorption spectrometry is described. The samples are suspended in HCl and sonicated until homogeneous and reduced particle size slurry formation. Several aspects were studied: acidity of the medium, sonication time, and slurry formation in different matrices. The procedure described permits the use of direct calibration, with KCN addition as masking agent of interfering ions (Cu, Pb, Ni and Zn) present in the environmental matrices. Supernatant analysis of these last samples experimentally shown that preparation of the suspension with 6 mol l−1 HCl concentration led to quantitative extraction of Cd. Biological materials analysis needed the use of the standard addition calibration method due to the high matrix effect observed. Supernatant analysis in biological samples does not give a total Cd recovery for all of them. The detection limits observed for Cd were 0.05 and 0.2 μg l−1 for supernatant and slurry analysis respectively in environmental samples, while in biological samples were 0.2 and 0.6 μg l−1 for supernatant and slurry analysis, respectively. In all case the better precision was obtained for supernatant analysis (3–6%) than slurry analysis (6–12%). The results obtained by analysing different reference materials (sewage sludge, city waste incineration, Antarctic krill and human hair) showed good agreement with the certified value confirming the validity of such a method for Cd determination instead to wet digestion procedures.
Talanta 03/2000; · 3.79 Impact Factor
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ABSTRACT: The environmental impact of some organotin compounds (OTC) has given particulate importance to analytical studies. This paper reports the first attempt to apply the emerging molecular imprinting technology to this field. Several imprinted polymers have been synthesised by the non-covalent free radical approach using sodium methacrylate (NaMA) or 4-vinylpyridine (4-VP) as monomers in the presence of TBT as template molecule in three different polymerisation media (toluene, acetonitrile and methanol/water). The ability of the polymers synthesised to retain and distinguish TBT from its degradation products has been evaluated and optimized. The results clearly showed the presence of cavities within the polymeric matrix allowing specific recognition of TBT. Cross-reactivity from other Sn species (monobutyltin (MBT), dibutyltin (DBT) and inorganic Sn) has also been evaluated. Rapid and direct differentiation of TBT from its main degradation products in seawater was achieved. The analytical characteristics included linearity (0.05–50 μg l−1), a pre-concentration factor of 150, and a quantification limit of 0.04 μg l−1 for 1 l.
Analytica Chimica Acta.
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ABSTRACT: A new adsorbent based on the imprinting technique with high retention capacity and pre-concentration factor has been synthesized and tested for retention of inorganic and organotin compounds [tributyltinchloride (TBT), dibutyltindichloride (DBT), monobutylytintrichloride (MBT) and triphenyltinchoride (TPhT)]. The polymerization has been carried out in the presence of TBT, the target organotin compound of this work. These compounds can be quantitatively retained on this adsorbent over a wide pH range and after elution these compounds are determined by graphite furnace atomic absorption spectrometry (GFAAS). Only organotin compounds are eluted from the adsorbent with 0.1 M hydrochloric acid (HCl) in methanol (MeOH) solution whereas inorganic tin is eluted later on with a suitable complexing agent such as citric acid. Linearity is obtained in the concentration range 0.1–4 ng (5–200 μg l−1) for each organotin compound with a correlation coefficient not less than 0.994 and relative standard deviation <5% even for complex samples such as sediments and seawater samples. The detection limit has been found to be 30 ng l−1. Various parameters related to determination, pre-concentration and GFAAS conditions have been optimized. The screening method proposed has been applied to the determination of organotin in natural sediments and seawater samples. The recovery is between 82 and 90% for TBT, DBT and TPhT and 50–55% for MBT in the case of sediment samples, while it is 97–103% for all the organotin compounds in seawater samples. The method has been conveniently validated using a standard sediment reference material.
Spectrochimica Acta Part B: Atomic Spectroscopy.
