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Multi-residue method for the determination of 16 recently used pesticides from various chemical groups in aqueous samples by using DI-SPME coupled with GC–MS
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
A simple and solvent-free multi-residue method has been optimized to determine 16 currently used pesticides from different chemical groups in aqueous samples. The extraction of analytes was carried out with direct immersion solid-phase microextraction (DI-SPME) and for the identification and quantitative determination gas chromatography coupled with mass spectrometry (GC–MS) was applied. Two commonly used adsorbent coatings have been applied and compared: 100μm of polydimethylsiloxane (PDMS) and 85μm of polyacrylate (PA). The method development parameters of DI-SPME, analyte desorption and GC–MS analysis have been outlined along with the final experimental conditions. When the optimum extraction conditions were applied (extraction time 60min, 10% (w/v) NaCl solution, 45°C) the limits of detection (LODs) were in the range of 0.015–0.13μgL−1 and the relative standard deviations (RSDs) were between 1.9 and 9.6%. The developed analytical method was successfully applied to the analysis of natural water samples from the following sources: river, sea, canal and rain.
Publication year: 2013
Source:Talanta, Volume 107
A simple and solvent-free multi-residue method has been optimized to determine 16 currently used pesticides from different chemical groups in aqueous samples. The extraction of analytes was carried out with direct immersion solid-phase microextraction (DI-SPME) and for the identification and quantitative determination gas chromatography coupled with mass spectrometry (GC–MS) was applied. Two commonly used adsorbent coatings have been applied and compared: 100μm of polydimethylsiloxane (PDMS) and 85μm of polyacrylate (PA). The method development parameters of DI-SPME, analyte desorption and GC–MS analysis have been outlined along with the final experimental conditions. When the optimum extraction conditions were applied (extraction time 60min, 10% (w/v) NaCl solution, 45°C) the limits of detection (LODs) were in the range of 0.015–0.13μgL−1 and the relative standard deviations (RSDs) were between 1.9 and 9.6%. The developed analytical method was successfully applied to the analysis of natural water samples from the following sources: river, sea, canal and rain.
Highlights
► In this study DI-SPME–GC–MS methodology was developed. ► The 100μm of PDMS and 85μm of PA fibers were applied and compared. ► Sixteen recently used pesticides from various chemical groups were determined. ► Method was validated and applied to the analysis of water samples. ► Methodology is a valuable tool for monitoring selected pesticides in water samples.On-line microwave-based preconcentration device for inductively coupled plasma atomic emission spectrometry: Application to the elemental analysis of spirit samples
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
A microwave-based thermal nebulizer (MWTN) has been employed for the first time as on-line preconcentration device in inductively coupled plasma atomic emission spectrometry (ICP-AES). By the appropriate selection of the experimental conditions, the MWTN could be either operated as a conventional thermal nebulizer or as on-line analyte preconcentration and nebulization device. Thus, when operating at microwave power values above 100W and highly concentrated alcohol solutions, the amount of energy per solvent mass liquid unit (EMR) is high enough to completely evaporate the solvent inside the system and, as a consequence, the analyte is deposited (and then preconcentrated) on the inner walls of the MWTN capillary. When reducing the EMR to the appropriate value (e.g., by reducing the microwave power at a constant sample uptake rate) the retained analyte is swept along by the liquid-gas stream and an analyte-enriched aerosol is generated and next introduced into the plasma cell. Emission signals obtained with the MWTN operating in preconcentration-nebulization mode improved when increasing preconcentration time and sample uptake rate as well as when decreasing the nozzle inner diameter. When running with pure ethanol solution at its optimum experimental conditions, the MWTN in preconcentration-nebulization mode afforded limits of detection up to one order of magnitude lowers than those obtained operating the MWTN exclusively as a nebulizer. To validate the method, the multi-element analysis (i.e. Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn) of different commercial spirit samples in ICP-AES has been performed. Analyte recoveries for all the elements studied ranged between 93% and 107% and the dynamic linear range covered up to 4 orders of magnitude (i.e. from 0.1 to 1000μgL−1). In these analysis, both MWTN operating modes afforded similar results. Nevertheless, the preconcentration-nebulization mode permits to determine a higher number of analytes due to its higher detection capabilities.
Publication year: 2013
Source:Talanta, Volume 107
A microwave-based thermal nebulizer (MWTN) has been employed for the first time as on-line preconcentration device in inductively coupled plasma atomic emission spectrometry (ICP-AES). By the appropriate selection of the experimental conditions, the MWTN could be either operated as a conventional thermal nebulizer or as on-line analyte preconcentration and nebulization device. Thus, when operating at microwave power values above 100W and highly concentrated alcohol solutions, the amount of energy per solvent mass liquid unit (EMR) is high enough to completely evaporate the solvent inside the system and, as a consequence, the analyte is deposited (and then preconcentrated) on the inner walls of the MWTN capillary. When reducing the EMR to the appropriate value (e.g., by reducing the microwave power at a constant sample uptake rate) the retained analyte is swept along by the liquid-gas stream and an analyte-enriched aerosol is generated and next introduced into the plasma cell. Emission signals obtained with the MWTN operating in preconcentration-nebulization mode improved when increasing preconcentration time and sample uptake rate as well as when decreasing the nozzle inner diameter. When running with pure ethanol solution at its optimum experimental conditions, the MWTN in preconcentration-nebulization mode afforded limits of detection up to one order of magnitude lowers than those obtained operating the MWTN exclusively as a nebulizer. To validate the method, the multi-element analysis (i.e. Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn) of different commercial spirit samples in ICP-AES has been performed. Analyte recoveries for all the elements studied ranged between 93% and 107% and the dynamic linear range covered up to 4 orders of magnitude (i.e. from 0.1 to 1000μgL−1). In these analysis, both MWTN operating modes afforded similar results. Nevertheless, the preconcentration-nebulization mode permits to determine a higher number of analytes due to its higher detection capabilities.
Highlights
► Microwave-based preconcentration procedure. ► On-line preconcentration and/or nebulization device for ICP-AES. ► Elemental trace and ultra-trace analysis of spirit samples.Novel application of pyronin Y fluorophore as high sensitive optical sensor of glucose in human serum
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
This paper presents a novel, high sensitive, facile and rapid spectrofluorimetric method for the direct assessment of glucose in human serum samples. The strong fluorescence intensity of pyronin Y (PY) is found to be selectively quenched substantially by adding solutions of glucose. Therefore, a new quantitative method to determine glucose could be developed. The noticeable and specific quenching effect of glucose on PY emission could be attributed to the increase in the nonradiative interactions as a result of a charge-transfer excited state with the location of the positive charge at the xanthenes moiety. Various parameters namely, the best working solvent, the proper pH medium in addition to the concentration of PY fluorophore corresponding to maximum fluorescence intensity were closely investigated. Under optimal conditions, the standard curve was linear in the glucose concentration ranges from 5.0×10−9 to 1.0×10−6 molL−1 (r=0.994). The detection limit (S:N=3) (LOD) is 2.9×10−9 molL−1. Validation of this approach was done by examining glucose concentration in serum samples of twenty patient and ten health donors. Achieved recovery reached 99.63–100.43% and 99.57–100.70%, respectively, in good agreement with those provided from hospital using traditional method. The relative standard deviations (RSD) were estimated between 0.00–0.78% and 0.15–1.91%, respectively.
Publication year: 2013
Source:Talanta, Volume 107
This paper presents a novel, high sensitive, facile and rapid spectrofluorimetric method for the direct assessment of glucose in human serum samples. The strong fluorescence intensity of pyronin Y (PY) is found to be selectively quenched substantially by adding solutions of glucose. Therefore, a new quantitative method to determine glucose could be developed. The noticeable and specific quenching effect of glucose on PY emission could be attributed to the increase in the nonradiative interactions as a result of a charge-transfer excited state with the location of the positive charge at the xanthenes moiety. Various parameters namely, the best working solvent, the proper pH medium in addition to the concentration of PY fluorophore corresponding to maximum fluorescence intensity were closely investigated. Under optimal conditions, the standard curve was linear in the glucose concentration ranges from 5.0×10−9 to 1.0×10−6 molL−1 (r=0.994). The detection limit (S:N=3) (LOD) is 2.9×10−9 molL−1. Validation of this approach was done by examining glucose concentration in serum samples of twenty patient and ten health donors. Achieved recovery reached 99.63–100.43% and 99.57–100.70%, respectively, in good agreement with those provided from hospital using traditional method. The relative standard deviations (RSD) were estimated between 0.00–0.78% and 0.15–1.91%, respectively.
Highlights
► A novel spectrofluorimetric determination of glucose is established. ► It added a novel function of pyronin Y(PY) as a viable glucose fluorimetric probe. ► The method reveals glucose selective and substantial quenching of PY fluorescence. ► The method is rapid, facile, sensitive, interference free and reproducible.Development of ultrasensitive direct chemiluminescent enzyme immunoassay for determination of aflatoxin B1 in food products
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
A direct competitive chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) for determination of aflatoxin B1 (AFB1) was developed. To improve the assay sensitivity, a mixture of 3-(10′-phenothiazinyl)-propane-1-sulfonate and 4-morpholinopyridine previously optimized by a factorial design was used as enhancer of horseradish peroxidase-induced chemiluminescence. Varying the concentrations of the coating anti-AFB1 antibody and conjugate of AFB1 and horseradish peroxidase the conditions of the chemiluminescent assay were optimized. The values of the detection limit value and dynamic working range of CL-ELISA of AFB1 were 0.0015ngmL−1 and 0.003–0.03ngmL−1, respectively. It was shown that a dilution of rice and mung beans extracts in 5 and 10 times, respectively, prevented a matrix effect of the food products in CL-ELISA. The recovery values from the spiked samples of rice and mung beans were in the range of 90–104% and 102–117%, respectively. Studying 8 rice and 8 mung beans samples purchased in commercial stores the developed CL-ELISA allowed to find 3 samples (1 rice and 2 mung beans) containing AFB1, the content of AFB1 in one sample being higher than the maximum acceptable level established in the European Community.
Publication year: 2013
Source:Talanta, Volume 107
A direct competitive chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) for determination of aflatoxin B1 (AFB1) was developed. To improve the assay sensitivity, a mixture of 3-(10′-phenothiazinyl)-propane-1-sulfonate and 4-morpholinopyridine previously optimized by a factorial design was used as enhancer of horseradish peroxidase-induced chemiluminescence. Varying the concentrations of the coating anti-AFB1 antibody and conjugate of AFB1 and horseradish peroxidase the conditions of the chemiluminescent assay were optimized. The values of the detection limit value and dynamic working range of CL-ELISA of AFB1 were 0.0015ngmL−1 and 0.003–0.03ngmL−1, respectively. It was shown that a dilution of rice and mung beans extracts in 5 and 10 times, respectively, prevented a matrix effect of the food products in CL-ELISA. The recovery values from the spiked samples of rice and mung beans were in the range of 90–104% and 102–117%, respectively. Studying 8 rice and 8 mung beans samples purchased in commercial stores the developed CL-ELISA allowed to find 3 samples (1 rice and 2 mung beans) containing AFB1, the content of AFB1 in one sample being higher than the maximum acceptable level established in the European Community.
Highlights
► A direct competitive chemiluminescent ELISA for determination of aflatoxin B1 was developed. ► To improve the assay sensitivity a mixture of SPTZ and MORPH was used as chemiluminescence enhancer. ► Values of the LDL and working range of CL-ELISA of AFB1 were 0.0015ngmL−1 and 0.003–0.03ngmL−1. ► The content of AFB1 in commercial samples of rice and mung beans was estimated.Facile synthesis of titania nanoparticles coated carbon nanotubes for selective enrichment of phosphopeptides for mass spectrometry analysis
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
In this work, titania nanoparticles coated carbon nanotubes (denoted as CNTs/TiO2 composites) were synthesized through a facile but effective solvothermal reaction using titanium isopropoxide as the titania source, isopropyl alcohol as the solvent and as the basic catalyst in the presence of hydrophilic carbon nanotubes. Characterizations using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the CNTs/TiO2 composites consist of CNT core and a rough outer layer formed by titania nanoparticles (5–10nm). Measurements using wide angle X-ray diffraction (WAXRD), zeta potential and N2 sorption reveal that the titania shell is formed by anatase titania nanoparticles, and the composites have a high specific surface area of about 104m2/g. By using their high surface area and affinity to phosphopeptides, the CNTs/TiO2 composites were applied to selectively enrich phosphopeptides for mass spectrometry analysis. The high selectivity and capacity of the CNTs/TiO2 composites have been demonstrated by effective enrichment of phosphopeptides from digests of phosphoprotein, protein mixtures of β-casein and bovine serum albumin, human serum and rat brain samples. These results foresee a promising application of the novel CNTs/TiO2 composites in the selective enrichment of phosphopeptides.
Publication year: 2013
Source:Talanta, Volume 107
In this work, titania nanoparticles coated carbon nanotubes (denoted as CNTs/TiO2 composites) were synthesized through a facile but effective solvothermal reaction using titanium isopropoxide as the titania source, isopropyl alcohol as the solvent and as the basic catalyst in the presence of hydrophilic carbon nanotubes. Characterizations using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the CNTs/TiO2 composites consist of CNT core and a rough outer layer formed by titania nanoparticles (5–10nm). Measurements using wide angle X-ray diffraction (WAXRD), zeta potential and N2 sorption reveal that the titania shell is formed by anatase titania nanoparticles, and the composites have a high specific surface area of about 104m2/g. By using their high surface area and affinity to phosphopeptides, the CNTs/TiO2 composites were applied to selectively enrich phosphopeptides for mass spectrometry analysis. The high selectivity and capacity of the CNTs/TiO2 composites have been demonstrated by effective enrichment of phosphopeptides from digests of phosphoprotein, protein mixtures of β-casein and bovine serum albumin, human serum and rat brain samples. These results foresee a promising application of the novel CNTs/TiO2 composites in the selective enrichment of phosphopeptides.
Highlights
► Titania nanoparticles coated carbon nanotubes were synthesized via simple hydroythermal reaction. ► The materials were characterized by SEM, TEM and XRD. ► The materials were successfully applied to selective enrichment of phosphopeptides in real samples.Evaluation of the uncertainty associated with the off line HPLC–GC(FID) determination of 4-desmethyl sterols in vegetable oils
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
This paper discusses the estimation of the uncertainty of the chromatographic determination of 4-desmethyl sterols in vegetable oils, combining the off line HPLC fractionation of the analytes, from the unsaponifiable fraction of the samples, with their determination as TMS derivatives by GC(FID), using the data obtained from a single internal calibration (one surrogate) at one level and “bottom up” approach. The methodology used, makes possible to identify the main uncertainty contributions, find their origins, and reduce them. The final results show that the main contributions to the relative overall uncertainty are those closely related with the chemical aspects of the method, i.e. those related to derivatization reaction and quantification of the analytes, although others aspects, such as the addition of a mass of surrogate, are not negligible.
Publication year: 2013
Source:Talanta, Volume 107
This paper discusses the estimation of the uncertainty of the chromatographic determination of 4-desmethyl sterols in vegetable oils, combining the off line HPLC fractionation of the analytes, from the unsaponifiable fraction of the samples, with their determination as TMS derivatives by GC(FID), using the data obtained from a single internal calibration (one surrogate) at one level and “bottom up” approach. The methodology used, makes possible to identify the main uncertainty contributions, find their origins, and reduce them. The final results show that the main contributions to the relative overall uncertainty are those closely related with the chemical aspects of the method, i.e. those related to derivatization reaction and quantification of the analytes, although others aspects, such as the addition of a mass of surrogate, are not negligible.
Highlights
► Uncertainty of determination of 4-desmethyl sterols in vegetable oils is estimated. ► From Bottom-up strategy Ishikawa diagram for identification of the sources is used. ► The methodology implies HPLC fractionation of sterols-quantification by GC(FID). ► The main source arises from chemical stages as derivatization and quantification.A flow-batch analyzer using a low cost aquarium pump for classification of citrus juice with respect to brand
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
This paper proposes a novel flow-batch analyzer (FBA), which employs a compact, low-cost aquarium air pump as an alternative to a peristaltic pump. The feasibility of using this simple propulsion device is demonstrated in a case study involving the classification of citrus juice samples with respect to brand. For this purpose, UV–vis spectra and SIMCA (soft independent modelling of class analogies), PLS-DA (Partial Least Squares for Discriminant Analysis) and SPA-LDA (Linear Discriminant Analysis with variables selected by the Successive Projections Algorithm) are employed. Good classification results were obtained, thus indicating that the proposed FBA system is a viable alternative to the use of more costly peristaltic pumps. In addition, the smaller size and weight of the aquarium pump are useful features for the construction of portable FBAs to be deployed in field applications.
Publication year: 2013
Source:Talanta, Volume 107
This paper proposes a novel flow-batch analyzer (FBA), which employs a compact, low-cost aquarium air pump as an alternative to a peristaltic pump. The feasibility of using this simple propulsion device is demonstrated in a case study involving the classification of citrus juice samples with respect to brand. For this purpose, UV–vis spectra and SIMCA (soft independent modelling of class analogies), PLS-DA (Partial Least Squares for Discriminant Analysis) and SPA-LDA (Linear Discriminant Analysis with variables selected by the Successive Projections Algorithm) are employed. Good classification results were obtained, thus indicating that the proposed FBA system is a viable alternative to the use of more costly peristaltic pumps. In addition, the smaller size and weight of the aquarium pump are useful features for the construction of portable FBAs to be deployed in field applications.
Highlights
► Novel flow-batch analyzer using a compact, low-cost aquarium pump instead of a peristaltic pump. ► Classification of citrus juice samples with respect to brand on the basis of UV–vis spectra. ► Multivariate classification employing SIMCA, PLS-DA and SPA-LDA. ► Correct classification of all samples by using the proposed flow-batch analyzer.Disposable terbium (III) salicylate complex imprinted membrane using solid phase surface fluorescence method for fast separation and detection of salicylic acid in pharmaceuticals and human urine
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
In this work, a simple, low cost, selective and sensitive complex imprinted membrane (CIM) for solid-phase fluorescent detection was developed with terbium (III) salicylate as complex template. Terbium-sensitized luminescence was employed for monitoring salicylic acid (SA) based on the fluorescence enhancement effect of benzoic acid derivatives on lanthanide ion Tb (III). The resulting CIM showed good fluorescent response and high selectivity towards SA with Tb as pivot in protic solvents, while demonstrating better analytical performance than the controlled membranes. The optimized adsorption time was 10min, indicating rapid kinetics of the imprinted membrane. The linear response of CIM to SA was from 0.20 to 10mg/L with limit of detection (LOD) of 0.040mg/L. The prepared CIM was successfully applied to the analysis of salicylic acid in pharmaceuticals and spiked human urine with recoveries of 80.6%–88.1%. The analytical results of the proposed method were in good agreement with those obtained by high performance liquid chromatography (HPLC) method, indicating that the developed membrane has acceptable practicability for fast determination of SA in real samples.
Publication year: 2013
Source:Talanta, Volume 107
In this work, a simple, low cost, selective and sensitive complex imprinted membrane (CIM) for solid-phase fluorescent detection was developed with terbium (III) salicylate as complex template. Terbium-sensitized luminescence was employed for monitoring salicylic acid (SA) based on the fluorescence enhancement effect of benzoic acid derivatives on lanthanide ion Tb (III). The resulting CIM showed good fluorescent response and high selectivity towards SA with Tb as pivot in protic solvents, while demonstrating better analytical performance than the controlled membranes. The optimized adsorption time was 10min, indicating rapid kinetics of the imprinted membrane. The linear response of CIM to SA was from 0.20 to 10mg/L with limit of detection (LOD) of 0.040mg/L. The prepared CIM was successfully applied to the analysis of salicylic acid in pharmaceuticals and spiked human urine with recoveries of 80.6%–88.1%. The analytical results of the proposed method were in good agreement with those obtained by high performance liquid chromatography (HPLC) method, indicating that the developed membrane has acceptable practicability for fast determination of SA in real samples.
Highlights
► A simple, fast and disposable metal complex imprinted membrane was fabricated. ► The CIM was used for detection of salicylic acid on solid phase surface fluorescence. ► Novel method was suitable for rapid analysis of salicylic acid in real samples.A sensitive enzymeless sensor for hydrogen peroxide based on the polynucleotide-templated silver nanoclusters/graphene modified electrode
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
A novel, sensitive and enzymeless electrochemical sensor based on polynucleotide-templated silver nanoclusters (DNA-AgNCs)/graphene composite film was developed for the detection of hydrogen peroxide. The graphene modified glassy carbon electrode (GCE) was employed because graphene has several advantages including excellent conductivity, biocompatibility, and large surface area to volume ratio. In addition, it was found that DNA-AgNCs have remarkable electrocatalytic activity toward the reduction of hydrogen peroxide, and can be easily immobilized onto the surface of the graphene/GCE by π–π stacking. The sensor based on the (DNA-AgNCs)/graphene/GCE exhibited a rapid response (ca. 3s), a low detection limit (3μM), a wide linear range from 15μM to 23mM, high selectivity, as well as good repeatability. Moreover, the common interfering species, such as ascorbic acid, uric acid, dopamine, glutathione, and l-cysteine, did not result in any interference. This present work may expand the use of silver nanoclusters in the field of electrochemical sensor.
Publication year: 2013
Source:Talanta, Volume 107
A novel, sensitive and enzymeless electrochemical sensor based on polynucleotide-templated silver nanoclusters (DNA-AgNCs)/graphene composite film was developed for the detection of hydrogen peroxide. The graphene modified glassy carbon electrode (GCE) was employed because graphene has several advantages including excellent conductivity, biocompatibility, and large surface area to volume ratio. In addition, it was found that DNA-AgNCs have remarkable electrocatalytic activity toward the reduction of hydrogen peroxide, and can be easily immobilized onto the surface of the graphene/GCE by π–π stacking. The sensor based on the (DNA-AgNCs)/graphene/GCE exhibited a rapid response (ca. 3s), a low detection limit (3μM), a wide linear range from 15μM to 23mM, high selectivity, as well as good repeatability. Moreover, the common interfering species, such as ascorbic acid, uric acid, dopamine, glutathione, and l-cysteine, did not result in any interference. This present work may expand the use of silver nanoclusters in the field of electrochemical sensor.
Highlights
► We fabricated the electrochemical sensor with simplicity and high sensitivity. ► DNA-AgNCs were simply synthesized and assembled onto graphene by π–π stacking. ► DNA-AgNCs possess enhanced electrocatalysis toward the reduction of H2O2. Graphene was electrodeposited onto the glassy carbon electrode. ► Graphene is useful for the immobilization of more DNA-AgNCs onto the electrode.Determination of cadmium in tobacco by solid surface fluorescence using nylon membranes coated with carbon nanotubes
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
A new methodology based on fluorescent signal enhancement of o-cresolphthalein (o-CPT) for traces of cadmium determination is proposed. The dye was retained on membrane filters in the presence of a micellar surfactant solution of carbon nanotubes (CNTs). All the experimental variables that influence both the preconcentration procedure and the fluorimetric sensitivity were carefully optimized. The calibration graph using zeroth order regression was linear from 6.5ngL−1 to 5.65×105 ngL−1, with a correlation coefficient higher than 0.999. Under optimal conditions, the limits of detection and quantification were of 2ngL−1 and 6.5ngL−1. respectively. The proposed method showed good sensitivity and selectivity, with good tolerance to foreign ions, and it was applied to the determination of trace amounts of cadmium in leachate from cigarettes' tobacco samples with satisfactory results. The trueness of the recommended procedure was assessed through parallel analysis of the samples with electrothermal atomization atomic absorption spectrometry. This methodology represents an innovative and attractive application of membrane filters that enables metal traces determination by solid surface fluorescence.
Publication year: 2013
Source:Talanta, Volume 107
A new methodology based on fluorescent signal enhancement of o-cresolphthalein (o-CPT) for traces of cadmium determination is proposed. The dye was retained on membrane filters in the presence of a micellar surfactant solution of carbon nanotubes (CNTs). All the experimental variables that influence both the preconcentration procedure and the fluorimetric sensitivity were carefully optimized. The calibration graph using zeroth order regression was linear from 6.5ngL−1 to 5.65×105 ngL−1, with a correlation coefficient higher than 0.999. Under optimal conditions, the limits of detection and quantification were of 2ngL−1 and 6.5ngL−1. respectively. The proposed method showed good sensitivity and selectivity, with good tolerance to foreign ions, and it was applied to the determination of trace amounts of cadmium in leachate from cigarettes' tobacco samples with satisfactory results. The trueness of the recommended procedure was assessed through parallel analysis of the samples with electrothermal atomization atomic absorption spectrometry. This methodology represents an innovative and attractive application of membrane filters that enables metal traces determination by solid surface fluorescence.
Highlights
► New methodology for cadmium traces determination in tobacco samples. ► Carbon nanotube have been used for improve the sensitivity of fluorescent detection. ► It is an important contribution at green chemistry. ► This methodology showing good reproducibility with low operation cost. ► It uses non-polluting solvents preserving the analyte and the environment.Precise determination of U isotopic compositions in low concentration carbonate samples by MC-ICP-MS
19 February 2013,
11:02:45
30 March 2013
Publication year: 2013
Source:Talanta, Volume 107
We developed a fast and simple analytical procedure for precise determination of U isotopic compositions in low concentration natural samples. The main advantage of the new method is that it requires only 12ng U and can obtain all U isotopic ratios without using spike. Five carbonate reference materials (JCp-1, RKM-4, RKM-5, GBW04412 and GBW04413) and 3 international standards with different matrices (IAPSO, IRMM-3184 and CRM-U010) were analyzed for (234U/238U) and 238U/235U ratios by MC-ICPMS. Using our method, the results for these standards are in close agreement with the certified values, 1.144±0.004, 0.966±0.004 and 0.990±0.003 for (234U/238U) and 137.72±0.13, 137.64±0.15 and 98.63±0.04 for 238U/235U, in IAPSO, IRMM-3184 and CRM-U010, respectively. The long-term reproducibility of (234U/238U) and 238U/235U is 0.970±0.002 and 137.56±0.09; 1.144±0.004 and 137.72±0.13, respectively, for in-house U solution and IAPSO. The new (234U/238U) results for carbonates show much better precision than previous studies and also reflect their age variability. The obtained 238U/235U ratios, representing the first measurements in these carbonate specimens, are rather constant. The method described here requires only 12ng of U for analysis and can be completed in 5.2min. The approach provides a fast method to measure (234U/238U) and 238U/235U ratios in sample matrices commonly encountered in studies of chemical weathering, oceanography and paleoclimatology.
Publication year: 2013
Source:Talanta, Volume 107
We developed a fast and simple analytical procedure for precise determination of U isotopic compositions in low concentration natural samples. The main advantage of the new method is that it requires only 12ng U and can obtain all U isotopic ratios without using spike. Five carbonate reference materials (JCp-1, RKM-4, RKM-5, GBW04412 and GBW04413) and 3 international standards with different matrices (IAPSO, IRMM-3184 and CRM-U010) were analyzed for (234U/238U) and 238U/235U ratios by MC-ICPMS. Using our method, the results for these standards are in close agreement with the certified values, 1.144±0.004, 0.966±0.004 and 0.990±0.003 for (234U/238U) and 137.72±0.13, 137.64±0.15 and 98.63±0.04 for 238U/235U, in IAPSO, IRMM-3184 and CRM-U010, respectively. The long-term reproducibility of (234U/238U) and 238U/235U is 0.970±0.002 and 137.56±0.09; 1.144±0.004 and 137.72±0.13, respectively, for in-house U solution and IAPSO. The new (234U/238U) results for carbonates show much better precision than previous studies and also reflect their age variability. The obtained 238U/235U ratios, representing the first measurements in these carbonate specimens, are rather constant. The method described here requires only 12ng of U for analysis and can be completed in 5.2min. The approach provides a fast method to measure (234U/238U) and 238U/235U ratios in sample matrices commonly encountered in studies of chemical weathering, oceanography and paleoclimatology.
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