Publications by authors named "Jean-Jacques Aaron"

25 Publications

  • Page 1 of 1

A spectrofluorimetric method for the determination of pindolol in natural waters using various organic and cyclodextrin media.

Environ Sci Pollut Res Int 2021 Oct 14;28(39):55029-55040. Epub 2021 Jun 14.

Laboratoire Géomatériaux et Environnement (LGE), EA 4119, Université Paris-Est Marne-la-Vallé, 5 Boulevard Descartes, Bâtiment IFI, 77454, Marne-la-Vallée Cedex 2, France.

A simple, sensitive, and rapid spectrofluorimetric method was developed for the determination of the β-blocker pindolol. The native fluorescence of pindolol was measured in different organic solvents and in cyclodextrin aqueous media. The highest fluorescence signal was obtained in 2-propanol at λ = 303 nm with λ = 260 nm. Analytical figures of merit for the spectrofluorimetric determination of pindolol were satisfactory, with wide linear dynamic range (LDR) values of two orders of magnitude, and rather low limit of detection (LOD) values between 0.2 and 8.7 ng/mL. Moreover, the addition of cyclodextrins (HP-β-CD and β-CD) in aqueous media enhanced the fluorescence of pindolol. In addition, the inclusion complexes of pindolol with cyclodextrins were investigated and the stability constants of complexes were calculated by means of the method of nonlinear regression (NLR). The method was successfully applied to the analysis of tap water and natural water samples, spiked with pindolol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-021-14801-wDOI Listing
October 2021

Toxic heavy metals: impact on the environment and human health, and treatment with conducting organic polymers, a review.

Environ Sci Pollut Res Int 2020 Aug 6;27(24):29927-29942. Epub 2020 Jun 6.

Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est, 5 Boulevard Descartes, Champs-sur-Marne, 77454, Marne la Vallée Cedex 2, France.

Water pollution by heavy metals has many human origins, such as the burning of fossil fuels, exhaust gases of vehicles, mining, agriculture, and incineration of solid and liquid wastes. Heavy metals also occur naturally, due to volcanoes, thermal springs activity, erosion, infiltration, etc. This water contamination is a threat for living beings because most heavy metals are toxic to humans and to aquatic life. Hence, it is important to find effective techniques for removing these contaminants in order to reduce the level of pollution of the natural waters. In this work, we have reviewed the toxicity of several heavy metals (mercury, lead, cadmium, chromium, nickel), their impact on the environment and human health, and the synthesis and characterization methods of conducting organic polymers (COPs) utilized for the removal of heavy metals from the environment. Therefore, this review was essentially aimed to present recent works and methods (2000-2020) on the environmental impact and toxicity of heavy metals and on the removal of toxic heavy metals, using chemically and/or electrochemically synthesized COPs. We have also stressed the great interest of COPs for the removal of toxic heavy metals from waters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-020-09354-3DOI Listing
August 2020

Polypyrrole-Wrapped Carbon Nanotube Composite Films Coated on Diazonium-Modified Flexible ITO Sheets for the Electroanalysis of Heavy Metal Ions.

Sensors (Basel) 2020 Jan 21;20(3). Epub 2020 Jan 21.

University Paris Est Creteil, CNRS, ICMPE, UMR7182, F-94320 Thiais, France.

Highly sensitive multicomponent materials designed for the recognition of hazardous compounds request control over interfacial chemistry. The latter is a key parameter in the construction of the sensing (macro) molecular architectures. In this work, multi-walled carbon nanotubes (CNTs) were deposited on diazonium-modified, flexible indium tin oxide (ITO) electrodes prior to the electropolymerization of pyrrole. This three-step process, including diazonium electroreduction, the deposition of CNTs and electropolymerization, provided adhesively-bonded, polypyrrole-wrapped CNT composite coatings on aminophenyl-modified flexible ITO sheets. The aminophenyl (AP) groups were attached to ITO by electroreduction of the in-situ generated aminobenzenediazonium compound in aqueous, acidic medium. For the first time, polypyrrole (PPy) was electrodeposited in the presence of both benzenesulfonic acid (dopant) and ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA), which acts as a chelator. The flexible electrodes were characterized by XPS, Raman and scanning electron microscopy (SEM), which provided strong supporting evidence for the wrapping of CNTs by the electrodeposited PPy. Indeed, the CNT average diameter increased from 18 ± 2.6 nm to 27 ± 4.8, 35.6 ± 5.9 and 175 ± 20.1 after 1, 5 and 10 of electropolymerization of pyrrole, respectively. The PPy/CNT/NH-ITO films generated by this strategy exhibit significantly improved stability and higher conductivity compared to a similar PPy coating without any embedded CNTs, as assessed by from electrochemical impedance spectroscopy measurements. The potentiometric response was linear in the 10-3 × 10 mol L Pb(II) concentration range, and the detection limit was 2.9 × 10 mol L at S/N = 3. The EGTA was found to drastically improve selectivity for Pb(II) over Cu(II). To account for this improvement, the density functional theory (DFT) was employed to calculate the EGTA-metal ion interaction energy, which was found to be -374.6 and -116.4 kJ/mol for Pb(II) and Cu(II), respectively, considering solvation effects. This work demonstrates the power of a subtle combination of diazonium coupling agent, CNTs, chelators and conductive polymers to design high-performance electrochemical sensors for environmental applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s20030580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037355PMC
January 2020

A novel fluorescent sensor based on electrosynthesized benzene sulfonic acid-doped polypyrrole for determination of Pb(II) and Cu(II).

Luminescence 2019 Aug 10;34(5):489-499. Epub 2019 Apr 10.

Laboratoire Géomatériaux et Environnement, Université Paris-Est, Marne-la-Vallée Cedex 2, France.

To develop conducting organic polymers (COPs) as luminescent sensors for determination of toxic heavy metals, a new benzene sulfonic acid-doped polypyrrole (PPy-BSA) thin film was electrochemically prepared by cyclic voltammetry (CV) on flexible indium tin oxide (ITO) electrode in aqueous solution. PPy-BSA film was characterized by FTIR spectrometry, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The optical properties of PPy-BSA were investigated by ultraviolet (UV)-visible absorption and fluorescence spectrometry in dimethylsulfoxide (DMSO) diluted solutions. PPy-BSA fluorescence spectra were strongly quenched upon increasing copper(II) ion (Cu ) and lead(II) ion (Pb ) concentrations in aqueous medium, and linear Stern-Volmer relationships were obtained, which indicated the existence of a main dynamic fluorescence quenching mechanism. BSA-PPy sensor showed a high sensitivity for detection of both metallic ions, Cu and Pb , with very low limit of detection values of 3.1 and 18.0 nM, respectively. The proposed quenching-fluorimetric sensor might be applied to the determination of traces of toxic heavy metallic ions in water samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bio.3626DOI Listing
August 2019

Establishment of an EC database of pesticides using a Vibrio fischeri bioluminescence method.

Luminescence 2019 Aug 4;34(5):508-511. Epub 2019 Apr 4.

Laboratory LGE, Champs-sur-Marne, University Paris-Est Marne la Vallée, 77454, Marne-la-Vallée Cedex 2, France.

An EC database was established to assess the acute toxicity of 16 PESTANAL pesticide standards and of seven pesticide commercial formulations using a Vibrio fischeri bioluminescence method. Half maximal effective concentration (EC ) is defined as the concentration of pollutant (in this case, pesticide) destroying 50% of the bacteria population and causing 50% bioluminescence inhibition, after a specified exposure time. Linear curves of bioluminescence inhibition versus pesticide concentration and EC values were obtained for exposure times (t) of 5 or 15 min for these pesticides. The EC values ranged from 6.90 × 10 to 0.83 mg/ml (t = 5 min), and from 9.00 × 10 to 0.37 mg/ml (t = 15 min) for pesticide standards, plus from 0.0077 to 0.74 mg/ml (t = 5 min), and from 0.0076 and 0.57 mg/ml (t = 15 min) for pesticide commercial formulations. The EC database allowed classification of the pesticides under study into three categories according to their toxicity: very toxic, toxic and moderately toxic. These results demonstrated that the establishment of an EC database and of linear curves of bioluminescence inhibition versus the pesticide concentration resulted in very important and irreplaceable tools to estimate the global and individual toxicity of pesticides present in environmental samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bio.3628DOI Listing
August 2019

Combination of photoinduced fluorescence and GC-MS for elucidating the photodegradation mechanisms of diflubenzuron and fenuron pesticides.

Luminescence 2019 Aug 19;34(5):465-471. Epub 2019 Feb 19.

Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est Marne-la-Vallée, 5 boulevard Descartes, Champs-sur-Marne, Marne-la-Vallée Cedex 2, France.

Diflubenzuron (DFB) and fenuron (FEN) are benzoylurea and phenylurea pesticides, widely used in Senegal, that do not exhibit any natural fluorescence, but can be determined by means of photoinduced fluorescence (PIF) methods. Photodegradation of DFB and FEN yielded a number of fluorescent and non-fluorescent photoproducts. For both pesticides, at least 10 photoproducts were detected and identified by gas chromatography-mass spectrometry (GC/MS). To identify the formed fluorescent DFB and FEN photoproducts, their fluorescence spectra were compared with those of standard compounds, including phenol and p-hydroxyaniline.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bio.3612DOI Listing
August 2019

Tracking metal ions with polypyrrole thin films adhesively bonded to diazonium-modified flexible ITO electrodes.

Environ Sci Pollut Res Int 2018 Jul 9;25(20):20012-20022. Epub 2018 May 9.

Université Paris Est, CNRS, ICMPE (UMR 7182), 2-8 rue Henri Dunant, 94320, Thiais, France.

Adhesively bonded polypyrrole thin films doped with benzene sulfonic acid (BSA) were electrodeposited on aminobenzenediazonium-modified flexible ITO electrodes and further employed for the detection of Pb, Cu, and Cd metal ions in aqueous medium. The aminophenyl (AP) adhesive layer was grafted to ITO by electroreduction of the in situ generated parent diazonium compound. Polypyrrole (PPy) thin films exhibited remarkable adhesion to aminophenyl (ITO-AP). The strongly adherent polypyrrole films exhibited excellent electroactivity in the doped state with BSA which itself served to chelate the metal ions in aqueous medium. The surface of the resulting, modified flexible electrode was characterized by XPS, SEM, and electrochemical methods. The ITO-AP-PPy electrodes were then used for the simultaneous detection of Cu, Cd, and Pb by differential pulse voltammetry (DPV). The detection limits were 11.1, 8.95, and 0.99 nM for Cu, Cd, and Pb, respectively. In addition, the modified electrodes displayed a good reproducibility, making them suitable for the determination of heavy metals in real wastewater samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-018-2140-xDOI Listing
July 2018

Removal of lead and cadmium from aqueous solutions by using 4-amino-3-hydroxynaphthalene sulfonic acid-doped polypyrrole films.

Environ Sci Pollut Res Int 2018 Mar 9;25(9):8581-8591. Epub 2018 Jan 9.

Laboratoire Géomatériaux et Environnement, Université Paris-Est, EA 4508, UPEM, 77454, Marne-la-Vallée, France.

Water pollution by heavy metals is a great health concern worldwide. Lead and cadmium are among the most toxic heavy metals because they are dangerous for the human and aquatic lives. In this work, the removal of lead and cadmium from aqueous solutions has been studied using electrosynthesized 4-amino-3-hydroxynaphthalene-1-sulfonic acid-doped polypyrrole (AHNSA-PPy) films as a new adsorbent. Two distinct methods, including the immersion method, based on the Pb and Cd spontaneous removal by impregnation of the polymer in the solution, and the electro-elimination method, consisting of removal of Pb and Cd ions from the solution by applying a small electrical current (5 mA) to the polymer film, were developed: the evolution of Pb and Cd concentrations with time was monitored by inductively coupled plasma optical emission spectrometry (ICP-OES). The effect of pH on the adsorption and electro-elimination of Pb and Cd using the AHNSA-PPy film was investigated and optimized, showing that the ionic adsorption and electro-elimination processes were highly pH-dependent. The kinetics of Pb and Cd adsorption and electro-elimination were found to follow second-order curves. The maximum adsorption capacity values of the AHNSA-PPy film were 64.0 and 50.4 mg/g, respectively, for Pb and Cd. The removal efficiency values were, respectively, for Pb and Cd, 80 and 63% by the immersion method, and 93 and 85% by the electro-elimination method. Application of both methods to Senegal natural waters, fortified with Pb and Cd, led to removal efficiency values of, respectively for Pb and Cd, 76-77 and 58-59% by the immersion method, and of 82-90 and 80-83%, by the electro-elimination method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-017-1111-yDOI Listing
March 2018

Development of online automatic detector of hydrocarbons and suspended organic matter by simultaneously acquisition of fluorescence and scattering.

Spectrochim Acta A Mol Biomol Spectrosc 2018 Mar 3;192:117-121. Epub 2017 Nov 3.

Laboratory OPTIMAG, EA 938, Faculty of Science and Technology, Brest University, 6 Avenue Victor Le Gorgeu, 29285 Brest Cedex, France. Electronic address:

Permanent online monitoring of water supply pollution by hydrocarbons is needed for various industrial plants, to serve as an alert when thresholds are exceeded. Fluorescence spectroscopy is a suitable technique for this purpose due to its sensitivity and moderate cost. However, fluorescence measurements can be disturbed by the presence of suspended organic matter, which induces beam scattering and absorption, leading to an underestimation of hydrocarbon content. To overcome this problem, we propose an original technique of fluorescence spectra correction, based on a measure of the excitation beam scattering caused by suspended organic matter on the left side of the Rayleigh scattering spectral line. This correction allowed us to obtain a statistically validated estimate of the naphthalene content (used as representative of the polyaromatic hydrocarbon contamination), regardless of the amount of suspended organic matter in the sample. Moreover, it thus becomes possible, based on this correction, to estimate the amount of suspended organic matter. By this approach, the online warning system remains operational even when suspended organic matter is present in the water supply.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.saa.2017.11.004DOI Listing
March 2018

Removal of Cr(VI) from aqueous solution using electrosynthesized 4-amino-3-hydroxynaphthalene-1-sulfonic acid doped polypyrrole as adsorbent.

Environ Sci Pollut Res Int 2017 Sep 20;24(26):21111-21127. Epub 2017 Jul 20.

Laboratoire Géomatériaux et Environnement, Université Paris-Est, EA4508, UPEM, 77454, Marne la Vallée, France.

Polypyrrole (PPy) conducting films, doped with 4-amino-3-hydroxynaphthalene sulfonic acid (AHNSA), were electrosynthesized by anodic oxidation of pyrrole on Pt and steel electrodes in aqueous medium (0.01 M AHNSA +0.007 M NaOH, using cyclic voltammetry (CV), and their electrochemical properties were studied. Fourier-transform infrared (FT-IR) spectroscopy confirmed the formation of AHNSA-PPy films. Their morphology was characterized by scanning electron microscopy (SEM), and their optical properties, including UV-VIS absorption and fluorescence spectra, were also investigated. AHNSA-PPy films were used for the removal of chromium(VI) from aqueous solution, by means of the immersion method and the Cr(VI) electro-reduction method. The effect of various experimental parameters, including the adsorbent (polymer) mass, pH, type of electrodes, and current intensity, on the adsorption of chromium by the polymer was performed and optimized. The adsorption and electro-reduction of (Cr VI) on the AHNSA-PPy film surface were found to be highly pH-dependent, and the kinetics of Cr(VI) adsorption and electro-reduction followed second-order kinetic curves. Apparent second-order rate constants were about three times higher for the Cr(VI) electro-reduction method than for the immersion method, indicating that the use of electro-reduction method significantly accelerated the chromium adsorption process on polymer. The maximum adsorption capacity of the AHNSA-PPy film for chromium was 224 mg g. A 96% chromium removal from pure aqueous solution was reached within about 48 h by the immersion method, but only within about 6 h by the Cr(VI) electro-reduction method. Application of both methods to Cr(VI) fortified natural waters of Senegal led to chromium removal efficiency high values (93 to 96% according to the type of natural water).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-017-9713-yDOI Listing
September 2017

Fluorescence Quenching of Two Coumarin-3-carboxylic Acids by Trivalent Lanthanide Ions.

J Fluoresc 2017 Mar 6;27(2):619-628. Epub 2016 Dec 6.

Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est Marne-la-Vallée, 5 boulevard Descartes, Champs-sur-Marne, 77454, Marne-la-Vallée Cedex 2, France.

The effects of various trivalent lanthanide ions (acetates of Ce, Er, Eu, Nd) on the electronic absorption and fluorescence spectra of un-substituted coumarin-3-carboxylic acid (CCA) and 7-N,N-diethylamino-coumarin-3-carboxylic acid (DECCA) have been investigated in dimethylsulfoxide (DMSO) at room temperature. Depending on the lanthanide ion nature and concentration, significant spectral changes of absorption bands occurred for both coumarin derivatives. These spectral changes were attributed to the formation of ground-state complexes between the coumarin carboxylate derivatives and lanthanide ions. The fluorescence quenching of CCA and DECCA upon increasing the lanthanide ion concentration was studied. Different quantitative treatments, including the Stern-Volmer equation, the Perrin equation and a polynomial equation, were applied and compared in order to determine the nature of the quenching mechanisms for both coumarin derivatives. The results suggested the contribution of both dynamic and static quenching. Significant differences of CCA and DECCA fluorescence quenching efficiency were also observed, depending on the lanthanide ion. DECCA fluorescence lifetime measurements, performed in the absence and in the presence of Ln, confirmed a contribution of static quenching.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10895-016-1990-1DOI Listing
March 2017

Synthesis and spectral properties of new fluorescent alkoxy-substituted thieno[3,2-b]indole derivatives.

Spectrochim Acta A Mol Biomol Spectrosc 2014 9;120:47-54. Epub 2013 Oct 9.

Laboratoire Physique des Matériaux Divisés et Interfaces, Université Paris-Est-Marne-la-Vallée, Champs-sur-Marne, 77454 Marne-la-Vallée Cedex 2, France.

The synthesis and optical properties of three new fluorescent alkoxy-substituted thieno[3,2-b]indole (TI) derivatives, including 7-methoxy thieno[3,2-b]indole (7-MeOTI), 6,7- methylenedioxythieno[3,2-b]indole (6,7-MDTI) and 6,7-dihexyloxythieno[3,2-b]indole, (6,7-DHTI), were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF), lifetimes (τF), and other photophysical parameters of the three TI derivatives were measured in DMSO solutions at room temperature. Theoretical electronic absorption and fluorescence spectra were also calculated by means of a molecular orbital (MO) method. For all three alkoxy-TI derivatives, the fluorescence emission maximum wavelength was significantly red shifted relative to un-substituted TI, which was attributed to delocalization of the fused hetero-aromatic ring π electronic system by the electron-donating alkoxy group(s). ΦF values varied from 0.12 to 0.19, according to the compound. τF were short, in the range 0.56-1.13 ns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.saa.2013.09.134DOI Listing
September 2014

Degradation and mineralization of sulcotrione and mesotrione in aqueous medium by the electro-Fenton process: a kinetic study.

Environ Sci Pollut Res Int 2012 Jun 25;19(5):1563-73. Epub 2011 Nov 25.

Laboratoire Géomatériaux et Environnement, Université Paris-Est, Marne-La-Vallée, France.

Introduction: The degradation and mineralization of two triketone (TRK) herbicides, including sulcotrione and mesotrione, by the electro-Fenton process (electro-Fenton using Pt anode (EF-Pt), electro-Fenton with BDD anode (EF-BDD) and anodic oxidation with BDD anode) were investigated in acidic aqueous medium.

Methods: The reactivity of both herbicides toward hydroxyl radicals was found to depend on the electron-withdrawing effect of the aromatic chlorine or nitro substituents. The degradation of sulcotrione and mesotrione obeyed apparent first-order reaction kinetics, and their absolute rate constants with hydroxyl radicals at pH 3.0 were determined by the competitive kinetics method.

Results And Discussion: The hydroxylation absolute rate constant (k(abs)) values of both TRK herbicides ranged from 8.20 × 10(8) (sulcotrione) to 1.01 × 10(9) (mesotrione) L mol(-1) s(-1), whereas those of the TRK main cyclic or aromatic by-products, namely cyclohexane 1,3-dione, (2-chloro-4-methylsulphonyl) benzoic acid and 4-(methylsulphonyl)-2-nitrobenzoic acid, comprised between 5.90 × 10(8) and 3.29 × 10(9) L mol(-1) s(-1). The efficiency of mineralization of aqueous solutions of both TRK herbicides was evaluated in terms of total organic carbon removal. Mineralization yields of about 97-98% were reached in optimal conditions for a 6-h electro-Fenton treatment time.

Conclusions: The mineralization process steps involved the oxidative opening of the aromatic or cyclic TRK by-products, leading to the formation of short-chain carboxylic acids, and, then, of carbon dioxide and inorganic ions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-011-0667-1DOI Listing
June 2012

Fluorescence properties and dipole moments of novel fused thienobenzofurans. Solvent and structural effects.

J Fluoresc 2011 Nov 13;21(6):2133-41. Epub 2011 Jul 13.

Laboratoire Géomatériaux et Environnement, EA 4119, Université Paris-Est Marne-la-Vallée, Marne la Vallée, France.

The electronic absorption, fluorescence excitation and emission spectra, and fluorescence quantum yields of novel fused thienobenzofurans, including thieno[3,2-b][1]benzofuran (1), [1]benzothieno[3,2-b]furan (2), and [1]benzothieno[3,2-b][1]benzofuran (3), were recorded in fourteen solvents of different polarities at room temperature. Compound 2 was not fluorescent. Experimental ground-state dipole moments of compounds 1-3 were measured in benzene at 298 K and compared with the corresponding theoretical dipole moment values. The solvent effects on the electronic absorption and fluorescence spectra of these thienobenzofurans were quantitatively investigated by means of solvatochromic correlations based on the Kawski-Chamma-Viallet and McRae equations. A weak negative solvatochromic behavior was found for these compounds, showing that their dipole moments are slightly lower in the excited singlet-state than in the ground-state. Kamlet-Abboud-Taft multiparameter relationships were also established for electronic absorption and fluorescence wavenumbers, and fluorescence quantum yields in most solvents, demonstrating the occurrence of specific solute-solvent interactions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10895-011-0914-3DOI Listing
November 2011

Revisiting the photophysical properties and excited singlet-state dipole moments of several coumarin derivatives.

Spectrochim Acta A Mol Biomol Spectrosc 2011 Aug 30;79(3):428-36. Epub 2011 Mar 30.

Laboratoire de Photochimie et d'Analyse, Faculté des Sciences et Techniques, Université Cheikh Anta DIOP, Dakar, Senegal.

The solvent effects on the electronic absorption and fluorescence emission spectra of several coumarins derivatives, containing amino, N,N-dimethyl-amino, N,N-diethyl-amino, hydroxyl, methyl, carboxyl, or halogen substituents at the positions 7, 4, or 3, were investigated in eight solvents with various polarities. The first excited singlet-state dipole moments of these coumarins were determined by various solvatochromic methods, using the theoretical ground-state dipole moments which were calculated by the AM1 method. The first excited singlet-state dipole moment values were obtained by the Bakhshiev, Kawski-Chamma-Viallet, Lippert-Mataga, and Reichardt-Dimroth equations, and were compared to the ground-state dipole moments. In all cases, the dipole moments were found to be higher in the excited singlet-state than in the ground state because of the different electron densities in both states. The red-shifts of the absorption and fluorescence emission bands, observed for most compounds upon increasing the solvent polarity, indicated that the electronic transitions were of π-π* nature.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.saa.2011.02.053DOI Listing
August 2011

Analytical applications of photoinduced chemiluminescence in flow systems--a review.

Anal Chim Acta 2010 Oct 15;679(1-2):17-30. Epub 2010 Sep 15.

Dept. Analytical Chemistry, University of Granada, Campus Fuentenueva S/N, E-18071 Granada, Spain.

In this review, the recent evolution and the state of the art of photochemical reactions coupled with chemiluminescence processes are presented. Different chemiluminescence systems have been considered together with suitable photochemical derivatization processes that can affect either the analyte of interest or even the chemiluminogenic reagent, producing some derivatives able to participate more efficiently in the CL reactions and enhancing the CL emission. The on-line integration of the photochemical reactions as well as the coupling of this resulting photoinduced chemiluminescence (PICL) method with dynamic analytical systems, such as flow injection analysis, liquid or gas chromatography and capillary electrophoresis, have been discussed. Important applications of PICL have been proposed in environmental, pharmaceutical and food analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.aca.2010.09.001DOI Listing
October 2010

Synthesis, electrochemical, and optical properties of new fluorescent, substituted thieno[3,2-b][1]benzothiophenes.

J Fluoresc 2010 Sep 13;20(5):1037-47. Epub 2010 Apr 13.

Laboratoire ITODYS, associé au CNRS UMR 7086, Université Paris Diderot, Paris 7, 15, rue Jean de Baïf, 75205, Paris Cedex 13, France.

The synthesis, electrochemical and optical properties of three fluorescent substituted thieno[3,2-b][1]benzothiophenes (TBT) derivatives, including 3-methoxythieno[3,2-b][1]benzothiophene (3-MeO-TBT), 2,3-dimethylthieno[3,2-b][1]benzothiophene (2,3-diMe-TBT), and 6-methoxythieno[3,2-b][1]benzothiophene-2-carboxylate (6-MeO-TBT-2-COOMe), were investigated. The oxidation potential values varied between 1.40 and 1.20 V/SCE according to the electronic substituent effect, and electropolymerization attempts, performed in 0.1 M LiClO(4) acetonitrile solution, led to the formation of very thin films of poly(3-MeO-TBT) and poly(2,3-di-Me-TBT). Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (Φ(F)) , lifetimes (τ(F)), and other photophysical parameters of the three new TBT derivatives were measured in DMSO solutions at room temperature. For the methyl-and methoxy-substituted TBT derivatives, the fluorescence emission peak were slightly red shifted relative to that of unsubstituted TBT (Δλ(em) = 1-12 nm) whereas, in the case of 6-MeO-TBT-2-COOMe, a rather strong red-shift (Δλ(em) = 73 nm) was attributed to the existence of a "push-pull" electronic interaction of the MeO and COOMe groups. All Φ(F) values were rather high, varying between 0.11 and 0.35, according to the substituent effect. Fluorescence decays were mono-exponential and τ(F) values were very short, ranging between 0.11 and 0.30 ns for the substituted TBT derivatives until study.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10895-010-0656-7DOI Listing
September 2010

Usefulness of cyclodextrin media for the determination of alpha-cypermethrin by photochemically induced fluorescence: analytical applications to natural waters.

Anal Bioanal Chem 2009 Jun 5;394(4):1089-98. Epub 2009 Feb 5.

Laboratoire de Photochimie et d'Analyse, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal.

The photochemically induced fluorescence (PIF) spectral properties of alpha-cypermethrin in organic solvents (hexane, dichloromethane, acetonitrile, ethanol) and in cyclodextrin aqueous solutions (beta-CD and 2-hydroxypropyl-beta-CD, 2-HP-beta-CD) were investigated. The photolysis kinetics of alpha-cypermethrin were evaluated in the various media. The PIF signal was found to be significantly enhanced in the CD media relative to the organic solvents. The stoichiometry and the formation constants of the alpha-cypermethrin inclusion complexes formed with the CDs were determined. The analytical performances of the PIF method were improved in the presence of HP-beta-CD relative to the other media, and a CD-enhanced PIF analytical method was developed. The limits of detection and limits of quantification ranged, respectively, between 6 and 98 ng/mL and between 24 and 343 ng/mL, depending on the medium. Application to the analysis of tap water and Senegal natural water samples collected close to agricultural areas and spiked with alpha-cypermethrin yielded satisfactory recoveries going from about 77% to 98%. An interference study of foreign species, including pesticides and inorganic ions likely to be present in natural waters, was also carried out.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-009-2611-5DOI Listing
June 2009

Study of the toxicity of diuron and its metabolites formed in aqueous medium during application of the electrochemical advanced oxidation process "electro-Fenton".

Chemosphere 2008 Nov 21;73(9):1550-6. Epub 2008 Sep 21.

Université Paris-Est Marne la Vallée, Laboratoire Géomatériaux et Géologie de l'Ingénieur, 5 Boulevard Descartes, Champs-sur-Marne, 77454 Marne-la-Vallée Cedex 2, France.

Diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea) is a herbicide belonging to the phenylurea family, widely used to destroy weeds on uncultivated surfaces. Because of its toxicity for aquatic organisms and suspicion of being carcinogenic for humans, diuron is the object of growing environmental concern. Therefore, we have developed the electro-Fenton method, an electrochemical advanced oxidation process (EAOP), to degrade diuron in aqueous medium, and we have studied the evolution of the toxicity of treated solution during the process. Indeed, the EAOPs catalytically generate hydroxyl radicals that oxidize the persistent organic pollutants, and can ultimately destroy and mineralize them. But, sometimes, relatively toxic organic metabolites are formed during the oxidation reaction. In this work, the evolution of toxicity of diuron aqueous solutions was studied at different initial concentrations, during treatment by the electro-Fenton method. Samples were collected at various electrolysis times and mineralization degrees during the treatment. The toxicity of the samples was measured using the bacteria Vibrio fischeri (Microtox) and the green alga Scenedesmus obliquus. Our results demonstrated that the toxicity of diuron aqueous solutions (concentrations=3.0-27.6 mg L(-1)) varied considerably with time. The formation and disappearance of several metabolites, having toxicity often stronger than that of the initial herbicide, were observed. To improve the efficiency of water decontamination, the electro-Fenton method should be applied during a time long enough (several hours) and at relatively high electrolysis current (I=250 mA) to reach a nearly complete mineralization of the herbicide in the aqueous medium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2008.07.082DOI Listing
November 2008

Luminescence and photophysical properties of benzo[a]phenothiazines--therapeutic, physico-chemical, and analytical applications.

Curr Drug Targets 2006 Sep;7(9):1083-93

ITODYS, Université Paris 7--Denis-Diderot, Associé au CNRS UMR 70-86, 1, rue Guy de la Brosse, 75005 Paris, France.

Luminescence studies on a series of new 12H-benzo[a]phenothiazines (BPHTs), possessing potentially useful antitumor therapeutic properties, are reviewed. The electronic absorption and fluorescence spectral properties of BPHTs, as well as their triplet- and singlet-excited states luminescence quenching are reviewed. Ground-state and singlet-excited state dipole moments and solvatochromic relationships are also described for these compounds. Studies on the formation of inclusion complexes between BPHTs and cyclodextrins (CDs), including CD-enhanced fluorescence, and thermodynamic constants and molecular geometry of these complexes, are discussed. The BPHTs antitumor properties in relation to their pi-electron density, and the physico-chemical and analytical applications based on their fluorescence and photophysical properties are also presented. This review article is based on selected literature data published in the last ten years (1993-2004).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/138945006778226606DOI Listing
September 2006

Fluorescence studies of anti-cancer drugs--analytical and biomedical applications.

Curr Drug Targets 2006 Sep;7(9):1067-81

ITODYS, Université Paris 7--Denis Diderot, 1, rue Guy de la Brosse, 75005, Paris, France.

The fluorescence properties of anticancer drugs (ACDs), including steady-state native fluorescence, time-resolved fluorescence, fluorescence polarization, excimer and exciplex emission, laser-induced fluorescence (LIF) with one- or two-photon excitation are reviewed, as well as the use of fluorogenic labels and fluorescent probes for the non-fluorescent ACDs. The interest of monitoring the fluorescence spectral changes to study the interactions of ACDs with biomolecules, such as DNA, proteins, vesicles, and the formation of complexes is discussed. The fluorescence methodologies used for ACDs studies, including fluorescence with two-photon excitation, liquid chromatography and capillary electrophoresis with fluorescence and laser-induced fluorescence (LIF) detection, and fluorescence microscopy, are also surveyed. Analytical and bioanalytical applications of fluorescence, indicating good selectivity and very low limits of detection at the nanomolar and picomolar level for most ACDs, are described. Biomedical and clinical applications of the fluorescence methods, mostly oriented towards the evaluation of the cytoxicity and anti-tumor potential of ACDs in single cells as well as in biological fluids, including blood, serum, plasma, cerebrospinal fluid, urine and feces, are also discussed in detail. This review is based on selected literature published in the last decade (1994-2003).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/138945006778226633DOI Listing
September 2006

Bioluminescence determination of enzyme activity of firefly luciferase in the presence of pesticides.

Luminescence 2005 May-Jun;20(3):192-6

Department of Medical and Experimental Biochemistry, Medical Faculty, Ss. Ciril and Metodius University, 50 Divizija 6, 1000 Skopje, R. Macedonia.

Firefly luciferase (EC 1.13.12.5) (FL) is the key enzyme in the firefly bioluminescence method (FB), which is widely used to determine the viability of living cells. The FB method can also be applied to monitoring the influence of different pollutants, such as pesticides. Firefly luciferase is a hydrophobic enzyme and its activity depends on the type of solvent, pH and substances present in the reaction mixture. The influence of three aromatic pesticides, including fenoxaprop-p-ethyl (I), diclofop-methyl (II) and metsulfuron methyl (III), on the enzyme activity was indirectly evaluated through the measurement of emitted light in the bioluminescence reaction, expressed in relative luminescence units (RLU). The reaction mixture used in the bioluminescence measurements consisted of: Tris buffer (pH 7.75), adenosine triphosphate (ATP) and ATP monitoring reagent, where FL is present. Ethanol-water solutions of each pesticide were then added at concentrations of 2.4 x 10(-4)-2.4 x 10(-8) mol/L. The FL activity inhibition factors (FL In%) were determined. The FL activity was maximally inhibited in the presence of all pesticides under study at a concentration of 2.4 x 10(-4) mol/L and was lowered by about 15-26% for pesticide I at concentrations of 2.4 x 10(-5)-2.4 x 10(-8) mol/L, whereas pesticides II and III, applied in the same concentration range, showed smaller FL inhibition values (5.3-20%). The pesticide degradation products (obtained after a 1 month period), measured in the same experimental conditions, in most cases exhibited a much less inhibitory effect on the enzyme activity than the corresponding initial pesticide.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bio.820DOI Listing
December 2005

A new on-line micellar-enhanced photochemically-induced fluorescence method for determination of phenylurea herbicide residues in water.

Luminescence 2005 May-Jun;20(3):138-42

ITODYS, University Denis Diderot, CNRS (UMR 70-86), 1 Rue Guy de la Brosse, 75005 Paris, France.

A new flow injection analysis micellar-enhanced photochemically induced fluorescence (FIA-MEPIF) method was developed for the determination of four phenylurea herbicides, including isoproturon, neburon, linuron and diuron. On-line photoconversion under UV irradiation of these herbicides into strongly fluorescent photoproducts was performed in buffered aqueous solutions and in the presence of surfactants [sodium dodecyl sulphate (SDS) or cetyl trimethyl ammonium chloride (CTAC)] at micellar concentrations. The MEPIF and FIA parameters were optimized. The analytical figures of merit for the determination of the four herbicides were satisfactory, with concentration linear dynamic ranges over about one to two orders of magnitude, detection limits of 0.33-0.92 mg[sol ]L and relative standard deviations of 1.3-11%, according to the compound. Application to the analysis of fortified tap water samples yielded good recovery values (91-103%, according to the herbicide). Our results show that the on-line MEPIF-FIA method is simple, versatile, sensitive and can be easily applied to quantify pollutant residues in multiresidue systems.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bio.817DOI Listing
December 2005

Solvatochromic correlations and ground- and excited-state dipole moments of curcuminoid dyes.

Spectrochim Acta A Mol Biomol Spectrosc 2004 Jul;60(8-9):1805-10

Department of Chemistry and Biochemistry, Florida Atlantic University, 777 Glades Road, P.O. Box 3091, Boca Raton, FL 33431-0991, USA.

Experimental dipole moments of curcumin (1) and of its parent compound dicinnamoylmethane (2) were determined in dioxane and benzene, respectively. Theoretical dipole moments were calculated using a combination of the PPP method (pi-moment) and a vector sum of the sigma-bond moments (sigma-moment) as well as by the ZINDO/1 method. Solvatochromic correlations were used to obtain the experimental first excited singlet-state dipole moments. The experimental electronic absorption spectra were compared with the calculated transitions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.saa.2003.07.013DOI Listing
July 2004

A multi-residue method for characterization and determination of atmospheric pesticides measured at two French urban and rural sampling sites.

Anal Bioanal Chem 2003 Dec 16;377(7-8):1148-52. Epub 2003 Sep 16.

ITODYS, Université Paris 7-Denis Diderot, associé au CNRS-UMR 7086, 1 rue Guy de la Brosse, 75005 Paris, France.

The extensive use of pesticides to protect agricultural crops can result in the transfer of these compounds into the atmosphere and their diffusion towards urban areas. Precise evaluation of the geographic impact of this type of pollution is important environmentally. In this paper, analytical methods for the sampling, characterization, and determination of agricultural pesticides in air were developed; the methods were then applied in the Paris and Champagne regions. Sixteen pesticides belonging to nine chemical families were monitored. Sampling was carried out in urban (Paris) and rural (Aube district) sites, utilizing either a high-volume pump (12.5 m3 h(-1)) (urban site) or a low-volume pump (2.3 m3 h(-1)) for the rural site. Quartz filters and polyurethane foams (PUF) were used for sampling in all cases. After extracting the samples and concentrating the recovered solutions, high-performance liquid chromatography (HPLC) analysis with UV detection was performed. Identification of the pesticides was confirmed by applying to the HPLC measurements a novel UV-detection procedure based on the normalized absorbance variation with wavelength (Noravawa procedure). The presence of metsulfuron methyl, isoproturon, linuron, deltamethrin (and/or malathion), and chlorophenoxy acids (2,4-D and MCPP) was found at the urban sampling site at levels ranging from about 1 to 1130 ng m(-3) of air, depending on the compound and sampling period. On the rural sampling site residues of isoproturon, deltamethrin (and/or malathion), MCPP, and 2,4-D were generally detected at higher levels (19-5130 ng m(-3)) than on the urban site, as expected. The effects of the weather conditions and agricultural activity on the atmospheric concentrations of pesticides are discussed, as are long-range atmospheric transfer processes for these pesticides.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-003-2196-3DOI Listing
December 2003
-->