Journal of Analytical Atomic Spectrometry, Mar 18, 2002
An on-line inorganic (InHg) and organomercury (OrHg) species separation, preconcentration and det... more An on-line inorganic (InHg) and organomercury (OrHg) species separation, preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS) coupled to a flow injection (FI) method was studied. The inorganic mercury species was retained on a column (id, 3 mm; length, 80 mm) charged with a Dowex 1X-8 resin (particle size 50–100 mesh) as the anionic complex formed with Methylthymol Blue (MTB), at pH 6.3. Previous oxidation of the organomercurial species permitted the ...
Journal of Trace Elements in Medicine and Biology, Mar 1, 2020
The interest in inorganic Hg toxicity and carcinogenicity has been pointed to target organs such ... more The interest in inorganic Hg toxicity and carcinogenicity has been pointed to target organs such as kidney, brain or placenta, but only a few studies have focused on the mammary gland. In this work, analytical combination techniques (SDS-PAGE followed by CV-AFS, and nanoUPLC-ESI-MS/MS) were used to determine proteins that could bind Hg in three human mammary cell lines. Two of them were tumorigenic (MCF-7 and MDA-MB-231) and the other one was the non-tumorigenic cell line (MCF-10A). There are no studies that provide this kind of information in breast cell lines with IHg treatment. Previously, we described the viability, uptake and the subcellular distribution of Hg in human breast cells and analysis of RNA-seq about the genes that encode proteins which are related to cytotoxicity of Hg. This work provides important protein candidates for further studies of Hg toxicity in the mammary gland, thus expanding our understanding of how environmental contaminants might affect tumor progression and contribute with future therapeutic methods.
Spectrochimica Acta Part B: Atomic Spectroscopy, Dec 1, 2019
Abstract A highly efficient magnetic dispersive micro-solid phase extraction (M-D-μSPE) method wa... more Abstract A highly efficient magnetic dispersive micro-solid phase extraction (M-D-μSPE) method was developed for Te preconcentration and speciation analysis in different environmental samples. A novel magnetic polymeric ionic liquid nanocomposite synthesized based on the Radziszewski reaction was applied for the selective retention of Te(IV) species, followed by elution with 5 mol L−1 HCl and determination by flow-injection hydride generation atomic fluorescence spectrometry. Te(VI) was selectively determined by difference between total Te and Te(IV) after a pre-reduction step. Studies on the sorption capacity of the nanocomposite were performed, while several parameters concerning the retention, separation and elution were optimized. A 100% retention efficiency and a sensitivity enhancement factor of 67 were achieved. Limits of detection of 1.9 ng L−1 and 3.7 ng L−1, and standard deviations of 4.3% and 5.1% were obtained for Te(IV) and Te(VI). A gas-liquid separator with a low dead volume was used for reduced dispersion of the flow injection signals and additional sensitivity enhancement. Finally, the feasibility of the proposed M-D-μSPE method for Te speciation was demonstrated by the analysis of several environmental samples, such as tap, rain, river and underground waters, soils and sediments, with excellent recovery results in spiked samples.
A novel on-line preconcentration and speciation analysis method for the simultaneous determinatio... more A novel on-line preconcentration and speciation analysis method for the simultaneous determination of inorganic Se and Te species is presented in this work. The methodology is based on the on-line formation of a hydrophobic ionic liquid (IL) directly in the liquid sample stream of a flow injection system, thus achieving an efficient and rapid extraction of the analytes complexed with ammonium pyrrolidine dithiocarbamate into the finely dispersed extractant droplets, that were then retained in a column filled with cotton. A full study of the chemical and hydrodynamical parameters was developed, including the right selection of the IL used as extractant and its concentration, pH, complexing reagent, sample and ion-exchange reagent volumes and column design. Additionally, a miniaturized external hydride generator was adapted to the spectrometer in order to increase the sensitivity of the atomic fluorescence measurements using only 250 μL of 5 mol L-1 HNO3 in methanol as eluent. The analytical figures of merit obtained for 15 mL of sample included sensitivity enhancement factors of 71, 70, 49 and 40 for Te(IV), Te(VI), Se(IV) and Se(VI), respectively, and limits of detection of 1.8 ng L-1 for both Te species, 2.6 ng L-1 for Se(IV) and 3.2 ng L-1 for Se(VI). After optimization, the method was successfully applied for the analysis of environmental samples: soils and sediments, as well as sea, river, underground and tap water.
Abstract A highly sensitive and selective method based on dispersive micro-solid phase extraction... more Abstract A highly sensitive and selective method based on dispersive micro-solid phase extraction (D-μ-SPE) technique was developed for the determination of inorganic Se species. A very simple and fast preconcentration procedure involving the use of pure nanosilica for the extraction of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate (APDC) was applied. Elution of the retained Se(IV) species from nanosilica was achieved with ethyl acetate followed by electrothermal atomic absorption spectrometry determination. For speciation analysis, Se(VI) was selectively quantified based on the difference between the concentrations of total inorganic Se and Se(IV) after a pre-reduction step. The interaction between the analyte and the extractant was characterized by FT-IR and an adsorption isotherm study. A 90% extraction efficiency was achieved after optimization of all factors concerning the extraction and elution steps, such as pH, ionic strength and type of chelating agent. Optimized conditions included pH = 2.0, 4.9 μmol L−1 APDC and the use of 1 mg nanosilica as adsorbent. A limit of detection of 1.4 ng L−1, a relative standard deviation of 4.8% and a 90-fold enhancement factor were obtained with 10 mL of sample. The developed method was finally applied to water samples from different origins and compositions, including rain, tap, underground, and sea.
Journal of Analytical Atomic Spectrometry, Mar 18, 2002
An on-line inorganic (InHg) and organomercury (OrHg) species separation, preconcentration and det... more An on-line inorganic (InHg) and organomercury (OrHg) species separation, preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS) coupled to a flow injection (FI) method was studied. The inorganic mercury species was retained on a column (id, 3 mm; length, 80 mm) charged with a Dowex 1X-8 resin (particle size 50–100 mesh) as the anionic complex formed with Methylthymol Blue (MTB), at pH 6.3. Previous oxidation of the organomercurial species permitted the ...
Journal of Trace Elements in Medicine and Biology, Mar 1, 2020
The interest in inorganic Hg toxicity and carcinogenicity has been pointed to target organs such ... more The interest in inorganic Hg toxicity and carcinogenicity has been pointed to target organs such as kidney, brain or placenta, but only a few studies have focused on the mammary gland. In this work, analytical combination techniques (SDS-PAGE followed by CV-AFS, and nanoUPLC-ESI-MS/MS) were used to determine proteins that could bind Hg in three human mammary cell lines. Two of them were tumorigenic (MCF-7 and MDA-MB-231) and the other one was the non-tumorigenic cell line (MCF-10A). There are no studies that provide this kind of information in breast cell lines with IHg treatment. Previously, we described the viability, uptake and the subcellular distribution of Hg in human breast cells and analysis of RNA-seq about the genes that encode proteins which are related to cytotoxicity of Hg. This work provides important protein candidates for further studies of Hg toxicity in the mammary gland, thus expanding our understanding of how environmental contaminants might affect tumor progression and contribute with future therapeutic methods.
Spectrochimica Acta Part B: Atomic Spectroscopy, Dec 1, 2019
Abstract A highly efficient magnetic dispersive micro-solid phase extraction (M-D-μSPE) method wa... more Abstract A highly efficient magnetic dispersive micro-solid phase extraction (M-D-μSPE) method was developed for Te preconcentration and speciation analysis in different environmental samples. A novel magnetic polymeric ionic liquid nanocomposite synthesized based on the Radziszewski reaction was applied for the selective retention of Te(IV) species, followed by elution with 5 mol L−1 HCl and determination by flow-injection hydride generation atomic fluorescence spectrometry. Te(VI) was selectively determined by difference between total Te and Te(IV) after a pre-reduction step. Studies on the sorption capacity of the nanocomposite were performed, while several parameters concerning the retention, separation and elution were optimized. A 100% retention efficiency and a sensitivity enhancement factor of 67 were achieved. Limits of detection of 1.9 ng L−1 and 3.7 ng L−1, and standard deviations of 4.3% and 5.1% were obtained for Te(IV) and Te(VI). A gas-liquid separator with a low dead volume was used for reduced dispersion of the flow injection signals and additional sensitivity enhancement. Finally, the feasibility of the proposed M-D-μSPE method for Te speciation was demonstrated by the analysis of several environmental samples, such as tap, rain, river and underground waters, soils and sediments, with excellent recovery results in spiked samples.
A novel on-line preconcentration and speciation analysis method for the simultaneous determinatio... more A novel on-line preconcentration and speciation analysis method for the simultaneous determination of inorganic Se and Te species is presented in this work. The methodology is based on the on-line formation of a hydrophobic ionic liquid (IL) directly in the liquid sample stream of a flow injection system, thus achieving an efficient and rapid extraction of the analytes complexed with ammonium pyrrolidine dithiocarbamate into the finely dispersed extractant droplets, that were then retained in a column filled with cotton. A full study of the chemical and hydrodynamical parameters was developed, including the right selection of the IL used as extractant and its concentration, pH, complexing reagent, sample and ion-exchange reagent volumes and column design. Additionally, a miniaturized external hydride generator was adapted to the spectrometer in order to increase the sensitivity of the atomic fluorescence measurements using only 250 μL of 5 mol L-1 HNO3 in methanol as eluent. The analytical figures of merit obtained for 15 mL of sample included sensitivity enhancement factors of 71, 70, 49 and 40 for Te(IV), Te(VI), Se(IV) and Se(VI), respectively, and limits of detection of 1.8 ng L-1 for both Te species, 2.6 ng L-1 for Se(IV) and 3.2 ng L-1 for Se(VI). After optimization, the method was successfully applied for the analysis of environmental samples: soils and sediments, as well as sea, river, underground and tap water.
Abstract A highly sensitive and selective method based on dispersive micro-solid phase extraction... more Abstract A highly sensitive and selective method based on dispersive micro-solid phase extraction (D-μ-SPE) technique was developed for the determination of inorganic Se species. A very simple and fast preconcentration procedure involving the use of pure nanosilica for the extraction of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate (APDC) was applied. Elution of the retained Se(IV) species from nanosilica was achieved with ethyl acetate followed by electrothermal atomic absorption spectrometry determination. For speciation analysis, Se(VI) was selectively quantified based on the difference between the concentrations of total inorganic Se and Se(IV) after a pre-reduction step. The interaction between the analyte and the extractant was characterized by FT-IR and an adsorption isotherm study. A 90% extraction efficiency was achieved after optimization of all factors concerning the extraction and elution steps, such as pH, ionic strength and type of chelating agent. Optimized conditions included pH = 2.0, 4.9 μmol L−1 APDC and the use of 1 mg nanosilica as adsorbent. A limit of detection of 1.4 ng L−1, a relative standard deviation of 4.8% and a 90-fold enhancement factor were obtained with 10 mL of sample. The developed method was finally applied to water samples from different origins and compositions, including rain, tap, underground, and sea.
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Papers by Rodolfo Wuilloud