Ethylenediaminetetraacetic Acid Solution Research Articles

A kinetic–thermodynamic study of silver leaching in thiosulfate–copper–ammonia–EDTA solutions

In this research, an analysis of the effect of ethylenediaminetetraacetic acid (EDTA), thiosulfate and cupric ions on the silver leaching kinetics was performed. For that purpose leaching experiments with pure metallic silver were carried out at different concentrations of these reagents at room temperature. The results of this study showed that small amounts of EDTA accelerate the leaching of silver more efficiently than higher concentrations due to an increase in the oxidation potential of the leaching solution. These results were in accord with Pourbaix diagrams and redox potential measurements. A synergistic effect was found in the silver leaching kinetics when the thiosulfate and EDTA concentrations were both decreased. On the other hand, the silver leaching kinetics was reduced at low Cu(II) concentrations due to the decrease in the oxidizing ability of the leaching solution.Characterization by SEM and EDXS of the silver in the first minutes of leaching revealed that the silver particles were coated by a layer of copper sulfides and copper oxides. Furthermore, characterization of the solid residue during the precipitation of silver in the leaching experiment was performed by the same analytical techniques, showing the presence of silver sulfide on the unreacted silver surface. The mechanism by which the silver sulfide is precipitated was found to be related to the copper sulfide formation. It was also observed that an increase in the concentration of EDTA promotes the silver dissolution avoiding the formation of copper sulfides or oxides; in these cases the process is controlled by the chemical reaction. These observations were also supported with Pourbaix and species distribution diagrams.

Structure of cadmium sulfide nanoparticle micelle in aqueous solutions

The structure of cadmium sulfide (CdS) micelle in stable aqueous solution of ethylenediaminetetraacetic acid was determined by dynamic light scattering, small-angle X-ray scattering and neutron scattering. The micelle aggregate is a single CdS nanoparticle with an average size of about 3 nm, the nanoparticle organic shell and the solvation shell are about 1 nm and 5 nm thick, respectively. These parameters were confirmed by the scanning semi-contact atomic force microscopy and powder X-ray diffraction studies of dry micelle cores isolated by high-speed centrifugation. The CdS micelle was correctly described by a simple double-shell model and was found to possess the structure corresponding to CdS quantum dots.

Regeneration of spent TiO2 nanoparticles for Pb (II), Cu (II), and Zn (II) removal

Spent sorbents in water treatment processes have potential risks to the environment if released without proper treatment. The aim of this work was to investigate the potential regeneration of commercially prepared nano-TiO2 (anatase) for the removal of Pb (II), Cu (II), and Zn (II) by pH 2 and ethylenediaminetetraacetic acid (EDTA) solutions. The percent of metal adsorption/desorption decreased with the increasing number of regeneration cycles, and the extent of decrease varied for each metal. Competitive effects were observed for the adsorption/desorption of different metals when the nano-TiO2 was regenerated by EDTA solutions. Nano-TiO2 was able to treat simulated metal polluted water with greater than 94 % adsorption and greater than 92 % desorption after four cycles of regeneration using pH 2 solution. These results demonstrated that nano-TiO2 can be regenerated and reused using pH 2 solution compared to an EDTA solution for aquatic metal removal, which makes nanosorbents promising and economically and environmentally more attractive in the application of water purification.

Synthesis of novel CoCx@C nanoparticles

CoCx nanoparticles encapsulated in carbon shells were synthesized using a pulsed plasma in liquid ethanol. This is the first time that monolithic cubic phase cobalt carbide nanoparticles have been obtained. X-ray diffraction refinement of the nanoparticles showed that the lattice parameter of prepared cubic phase cobalt carbide is larger than that of CoCx (44-0962) and cubic phase Co (15-0806 and 01-1259). The x-ray absorption fine structure spectra near the Co K-edge of the synthesized sample indicated differences from commercial metallic cobalt and cobalt oxide samples. High resolution transmission electron microscopy revealed that a thin carbon coating covered the surface of the nanoparticles. These carbon layers might isolate core CoCx material from the outside environment, and allow functionalization by carboxyl groups for the further purpose of targeted drug delivery. The obtained CoCx@C particles, with a crystallite size of about 10 nm confirmed by the electron microscope, aggregate into 20–40 nm secondary particles in distilled water as shown by dynamic light scattering, and possess high saturation magnetization of about 120 emu g−1. The sodium 3′-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzene sulfonic acid hydrate assay and defragmentation of deoxyribonucleic acid on MCF-7 cells after incubation with particles indicate relatively low cytotoxicity of CoCx@C nanoparticles, compared with micro-sized and nano-sized metallic cobalt particles and commonly used iron oxides. For the small sized CoCx@C particles, the release of cobalt ions was checked by a chelation method with ethylenediaminetetraacetic acid solution to be at a very low level compared with other reference materials.

Evidence of the protein content of bovine and human dental pulps by the action of endodontic irrigation solutions through electrophoretic patterns

Background: Sodium dodecyl sulfate polyacrylamide gel electrophoresis let to show the protein content of different tissues. Dental pulp contains connective tissue which is removed during the endodontic treatment. Many studies consider bovine rather than human pulp tissue because of its size. Aim: To evidence the protein content of bovine and human dental pulps and the action of endodontic irrigation solutions through electrophoretic patterns. Materials and Methods: Extracts of human and bovine dental pulps were prepared. Sodium hypochlorite, calcium hydroxide, chlorhexidine and ethylenediamine tetraacetic acid were used as irrigating solutions. Results: Bovine and human pulps have a small difference in two bands of proteins present between 74 kDa and 80 kDa. The denaturizing capacity of sodium hypochlorite and the washing action of calcium hydroxide and chlorhexidine were evidenced. Ethylenediamine tetraacetic acid solution was shown to contain proteins continuously during the endodontic root canal washing. Conclusions: Differences in pulp tissues and the action of irrigating solutions on their protein content would help on the understanding of the biological process of the endodontic treatment.

Evaluation of the different irrigation regimens with sodium hypochlorite and EDTA in removing the smear layer during root canal preparation

ObjectivesThe aim of this study was to compare, by scanning electron microscopy analysis, the cleaning efficacy of a 2.5% sodium hypochlorite (NaOCl) and a 17% ethylenediaminetetra-acetic acid (EDTA) solution with the two solutions either applied alternately or mixed together for smear layer removal after the use of each endodontic file in different root thirds. Materials and methodsFifty-four single-rooted human maxillary premolars were used and divided into three groups. Manual instrumentation was performed with K-Flexofiles with the crown-down technique; and divided in Group 1: canal preparation was performed with 2.5% NaOCl mixed with 17% EDTA in the root canal. Group 2: irrigation was performed alternately with 2.5% NaOCl and 17% EDTA. Group 3: only 2.5% NaOCl was used during all instrumentation and EDTA for 3min at the final. The mean scores for the smear layer by SEM after the use of each file were calculated and analysed. ResultsA statistically significant difference (P<0.05) was found among the instrumentation groups between the apical third and the middle and coronal thirds. In the apical third, the canal walls were often contaminated by inorganic debris and smear layer. ConclusionsThe alternate or mixed use of EDTA during instrumentation with 2.5% sodium hypochlorite was the most effective form of irrigation for the removal of smear layer on the cervical and middle thirds. No form of irrigation was sufficiently effective to remove the smear layer in the apical third. Clinical relevanceThe importance of the alternating use of 17% EDTA and 2.5% sodium hypochlorite during root canal instrumentation.

Spectrophotometric determination of EDTA in aqueous solution through ferroin formation using sodium sulfite as the reducer

This paper presents a simple, easy and reliable method for determination of EDTA (ethylenediaminetetraacetic acid) in aqueous system. Using EDTA chelating with ferric irons, an excessive amount of Fe3+ was added to EDTA solution, and Fe3+ in excess was reduced by addition of a Na2SO3 solution, the outcome ferrous ions were then reacted with 1,10-phenanthroline monohydrate (PTM) to form ferroin, a color developing reagent. The absorbance of the ferroin was determined using spectrophotometry, from which EDTA concentration was obtained. The method was tested for interferences and applied to determination of trace amount EDTA in its degradation by ozone oxidation, and the result compared with those from high-performance liquid chromatography. It was revealed that a low limit of 1.4μM for EDTA concentration detection was achieved with a high correlation coefficient of 0.999 combined with a low relative standard deviation of 0.6%. In contrast to all reported processes, where ferric ions in excess have to be separated from those chelated with EDTA prior to their reduction followed by interaction with PTM and spectrophotometric determination, the key merit of the present method is that EDTA concentration is determined without need of ferric separation, rendering the present process very easy. The method is also characterized by low cost, high precision and high reproducibility at the same time.

Evaluation of different irrigation protocols concerning the formation of chemical smear layer

The aim of this work was to evaluate, by means of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS), the different irrigation protocols concerning the formation of chemical smear layer (CSL). Fifty-five teeth were instrumented by using distilled water (DW) as irrigant. Next, the teeth were submitted to a protocol for removal of the mechanical smear layer produced. The teeth were divided into 11 groups, according to irrigation regimen. Then, the teeth were prepared and analyzed with SEM and EDS. Only in Group 1 [1 mL sodium hypochlorite (NaOCl) + 10 mL DW + 1 mL chlorhexidine (CHX) solution], Group 2 [1 mL NaOCl + 10 mL DW + 1 mL ethylenediaminetetraacetic acid (EDTA) + 10 mL DW + 1 mL CHX solution], and Group 3 [1 mL NaOCl + 10 mL DW + 1 mL citric acid (CA) + 10 mL DW + 1 mL CHX solution], the formation of CSL was observed. In the groups where CHX gel was used alone or in association with EDTA, CA, phosphoric acid (PA), and CHX solution, no formation of CSL was observed. According to the results found in the cases in which one wants to associate NaOCl with CHX, the protocol using PA (1 mL NaOCl + 10 mL DW + 1 mL PA + 10 mL DW + 1 mL CHX solution) did not induce formation of CSL.

Enhancement of electrokinetic decontamination with EDTA

The effect of ethylenediaminetetraacetic acid (EDTA) during electrokinetic decontamination (EKD) was investigated in this research. EDTA is a ligand that can form soluble complexes with precipitated heavy metals inside soil pores. Millpond sludge, primarily contaminated with lead (Pb) and zinc (Zn), was subjected to EKD with and without the presence of EDTA. Dilute EDTA solutions with strengths of 0.05 M and 0.125 M were injected into the millpond sludge by electroosmosis. Several beneficial effects of using EDTA were observed in this research. One was that the presence of EDTA substantially increased the electroosmotic (EO) flow in the millpond sludge indicating that it could significantly reduce the duration of EKD. Another advantage was that a significantly higher percentage of Pb and Zn removal was achieved from the solid phase due to the complexation of EDTA with these heavy metals. Also, EDTA was able to prevent the precipitation of metals at the cathode electrode, typically observed in EKD process.

Assessment of genotoxic effect of maleic acid and EDTA: a comparative in vitro experimental study

This study aims to evaluate and compare the genotoxic and apoptotic effect of aqueous solutions of ethylenediaminetetraacetic acid (EDTA) with that of maleic acid (MA) using Chinese hamster lung fibroblast (V79) cells growing in vitro. Exponentially growing V79 cells were treated with various concentrations of EDTA or MA alone for 30min, and genotoxic effect was analyzed by micronucleus as well as comet assays and the type of cell death by apoptotic cell measurements using microscopic and flow cytometric methods. For all the experiments, H2O2 was used as a positive control. Treatment of V79 cells with H2O2 resulted in significantly (P < 0.001) increased micronuclei and levels of DNA damage, whereas, EDTA/MA alone treated cells did not show significant increase of MN frequencies and comet parameters even at their higher concentrations when compared with that of untreated control. V79 cells treated with EDTA/MA for 30min showed a nonsignificant increase in the percentage of apoptotic and necrotic cells at their lower concentrations (0.025 and 0.05% for EDTA and MA, respectively). However, at higher concentrations, i.e., >IC50 (0.1 and 0.5%) for EDTA and MA resulted in increased number of apoptotic and necrotic cells when compared with the untreated group. This study clearly demonstrates that MA and EDTA are not potentially genotoxic agents and MA induced lesser apoptotic/necrotic death than that of EDTA at their clinically relevant doses. MA may have a better clinical acceptability with comparable smear layer removal ability. Hence, the results presented here might be an additional supporting evidence for the use of MA in endodontic practice.

Preparation of poly(methyl methacrylate) microcapsules by in situ polymerization on the surface of calcium carbonate particles

Poly(methyl methacrylate) (PMMA) microcapsules were prepared by the in situ polymerization of methyl methacrylate (MMA) and N,N′-methylenebisacrylamide on the surface of calcium carbonate (CaCO3) particles, followed by the dissolution of the CaCO3 core in ethylenediaminetetraacetic acid solution. The microcapsules were characterized using fluorescence microscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The average sizes of the CaCO3 particles and PMMA capsules were 3.8±0.6 and 4.0±0.6μm, respectively. A copolymer consisting of MMA and rhodamine B-bearing MMA was also used to prepare microcapsules for fluorescent microscopy observations. Fluorescein isothiocyanate-labeled bovine serum albumin was enclosed in the PMMA microcapsules and its release properties were studied.

Toxicity of Metal–Ethylenediaminetetraacetic Acid Solution as a Function of Chemical Speciation: An Approach for Toxicity Assessment

The influence of complexation by ethylenediaminetetraacetic acid (EDTA) on the toxicity of Cd(II), Cu(II), Cd(II), and Ni(II) was investigated. Result of the Microtox test, which is based on measuring the decrease of light emitted by Vibrio fischeri bacterium when exposed to a toxicant, was used as an indication of toxicity. The effect of pH and EDTA molar ratio that might potentially modify the percentage of chemical species in solution on toxicity was evaluated. In general, results indicate that toxicity decreases when increasing the pH value as well as the EDTA molar ratio. Chemical modeling was used to predict metal speciation and correlation analysis to relate chemical species with the obtained toxicity results. The species that most contribute to toxicity resulted to be MeCl(+) (Me = metal), which is formed as a consequence of the presence of the bioassay medium (2 % NaCl). A model that predicts metal-solution toxicity by using the chemical species, which most contribute to toxicity is proposed as a useful tool for toxicity assessment in waters containing metal ions and EDTA.

Modeling Adsorption of Copper on Amine-Functionalized SBA-15: Predicting Breakthrough Curves

AbstractDynamic experiments on the adsorption of copper ions were conducted in a laboratory packed bed containing amine-modified SBA-15 pellets. Breakthrough curves were analyzed at different flow rates and after two adsorption–desorption cycles. A model based on mass balance was developed and tested to predict the breakthrough curves under the different experimental conditions. The model was found to agree with the experimental data. Bed regeneration was performed by circulating a ethylenediaminetetraacetic acid solution through the column.

Preparation of free-suspended polyelectrolyte multilayer films using an alginate scaffold and their ion permeability

Free-suspended polyelectrolyte multilayer (PEM) films were prepared over an aperture (diameter, 1 or 3mm) in a glass plate to study ion permeation across the PEM films. PEM films were successfully constructed by layer-by-layer deposition of poly(allylamine hydrochloride) and poly(styrene sulfonate) on the surface of glass plate whose aperture had been filled with an alginate gel, followed by dissolution of the alginate gel in an ethylenediaminetetraacetic acid solution. PEM films thus prepared showed selective permeability for inorganic salts such as NaCl, KCl, CaCl2, Na2SO4, K3[Fe(CN)6], and K4[Fe(CN)6]. The results were rationalized based on the size and charge of the ions and the thickness and surface charges of films.

Gene Expression Analysis in Microdissected Samples from Decalcified Tissues

The aim of this study was to determine the impact of standard methods for processing decalcified highly mineralized tissues on RNA yield and quality from microdissected samples. Rat mandibles were fixed with either formalin-based or ethanol-based fixatives, decalcified in 20% ethylenediaminetetraacetic acid solution for 15 days, and embedded in paraffin. Transversal sections of the molars were mounted on membrane glass slides for laser capture microdissection. Unfixed frozen liver samples were used as controls to determine the impact of fixatives, decalcification and paraffin embedding on RNA integrity and recovery after sample preparation, and laser microdissection. Total RNA was obtained from periodontal ligament and fresh-frozen liver; RNA quality was assessed by Bioanalyzer, and 5 ng of total RNA was used for cDNA synthesis followed by gene expression analyses by polymerase chain reaction using 3 sets of primers for glyceraldehyde 3-phosphate dehydrogenase. Data analysis demonstrated that all fixed samples presented some level of RNA fragmentation as compared with fresh-frozen samples (P<0.05). Samples fixed with Protocol (10% formalin) showed the least RNA fragmentation as compared with other fixatives (P<0.05), and biologically useful RNA was extracted even from microdissected samples with a minimum RNA Integrity Number of 1.5. Moreover, RNA fragments up to 396 bp were assayable by reverse transcriptase-polymerase chain reaction, although short-targeted fragments as 74 bp were more consistently amplified. Although variable levels of RNA fragmentation should be expected, gene expression analysis can be performed from decalcified paraffin-embedded microdissected samples, with the best results obtained for short-targeted fragments around 70 bp.

Behavior of a ruthenium-titanium oxide film electrode (RTOE) in potentiometry

Polyfunctional properties of a ruthenium-titanium oxide electrode in the absence of polarization and the possibility of its application to the potentiometric detection of iron(III) titration with an ethylenediaminetetraacetic acid solution, acid-base and redox reaction types have been demonstrated. Mechanisms of reactions determining the potentials of electrodes of this type have been investigated by a number of methods.

Evaluation of metal ions in rice samples: extraction and direct determination by ICP OES

A method for extraction of metal ions present in rice samples using ammoniacal EDTA solution, pH > 10, as extractor agent is proposed under the following optimized conditions: 0.20 g of rice sample and 5.00 mL of ammoniacal EDTA (ethylenediaminetetraacetic acid) solution, with 5 min of ultrasound exposure time. Using robust ICP OES (inductively coupled plasma atomic emission spectrometry) conditions, direct analysis of the extraction solution was allowed, and the recovery values obtained were above 90% for most of the studied elements (P, K, Mg, Ca, Zn, Mn, Cu and Mo) with RSD < 5%. The results were in good agreement with those obtained by microwave-assisted extraction and for the reference material of rice flour (NIST SRM 1568a). The limits of detection of method were in the range of 0.007 mg kg-1 (Mn) - 48.68 mg kg-1 (K), showing adequate detectability for the determination of the analytes. The analysis of different samples indicated that Brazilian integral rice contains higher contents of the constituents studied, followed by parboiled rice, and the agulhinha rice a long and thin grain type.

&lt;i&gt;In Vitro&lt;/i&gt; Antioxidant Activity of Chitosan Aqueous Solution: Effect of Salt Form

Purpose: To investigate the effect of salt form on the antioxidant activities of chitosan aqueous solution.Methods: The antioxidant activities of chitosan acetate (CS-acetate), chitosan hydroxybenzotriazole (CS-HOBt), chitosan thiamine pyrophosphate (CS-TPP) and chitosan ethylenediaminetetraacetic acid (CS-EDTA) solution were determined employing various established in vitro system such as superoxide and hydroxyl radicals scavenging, metal ion chelating and reducing power. Their chemical structures were characterized by nuclear magnetic resonance (NMR) and Fourier transform infraredspectrophotometry (FT-IR).Results: NMR and FT-IR show confirmed formation of chitosan salts. The 50 % inhibition concentration (IC50) of superoxide and hydroxyl radicals was 0.349 &ndash; 1.34 and 0.34 &ndash; 1.54 mg/mL, respectively. Among the salt forms, CS-acetate (IC50 = 0.349 mg/mL) showed the highest superoxide radical scavenging effect while CS-HOBt (IC50 = 0.34 mg/mL) showed the highest hydroxyl radical scavenging effect. With regard to metal ion chelating activity, CS-EDTA showed the highest chelating activity (approx 100 % at 1 mg/mL) while the others showed 20 % activity at a concentration of 1 mg/mL. The results for reducing power indicate that CS-TPP had the highest reducing power.Conclusion: The results indicate that antioxidant activity varied with the salt form. Thus, CS salts may be used as a source of antioxidants for pharmaceutical applications.Keywords: Chitosan, Antioxidant, Hydroxybenzotriazole, Thiamine pyrophosphate, Ethylenediaminetetraacetic acid

Synthesis of Cerium‐Activated Yttrium Aluminate Based Fine Phosphors by an Aerosol Route

AbstractPolycrystalline fine powders of yttrium aluminate doped with Ce3+ were synthesised by spray pyrolysis of a polymeric precursor, which was obtained by dissolving the corresponding nitrates in a solution of ethylenediaminetetraacetic acid (EDTA) in ethylene glycol (EG). Aerosol decomposition was performed at 550 °C followed by an additional thermal treatment (900–1100 °C). The yield of either a single yttrium aluminium perovskite (YAP) phase or a single yttrium aluminium garnet (YAG) phase was investigated as a function of the predefined yttrium/aluminium ratio, the cerium doping concentration, the processing temperature, and the thermal‐treatment regime, which included the variation of the heating and cooling rates (dT/dt), the residence time (τ), and the atmosphere. Changes in the composition and structure of the precursor during thermal decomposition were investigated by thermogravimetric and differential thermal analysis (TGA/DTA) and FTIR spectroscopy. The particle morphology and structure were analysed by a combination of scanning electron microscopy and energy‐dispersive X‐ray spectroscopy (SEM/EDS) and by high‐resolution transmission electron microscopy (HR‐TEM). The structural refinement was based on the phase identification performed by X‐ray powder diffraction (XRPD). The emission spectra were recorded within the range 325–800 nm by applying excitation wavelengths of 297 (YAP) and 450 nm (YAG). The employed synthesis conditions assured the formation of spherical, non‐agglomerated particles with well‐developed surfaces and diameters between 200 and 800 nm. For a predefined Y/Al ratio of 1:1, lower processing temperatures combined with longer heat treatments under stationary conditions resulted in a multiphase system, composed of YAP, YAG, and monoclinic yttrium aluminate (YAM) phases. However, a short heat treatment with a high heating rate (200 °C/min) at higher temperatures results in the formation of a kinetically favoured pure YAP hexagonal phase. On the other hand, for a predefined Y/Al ratio of 3:5, the generation of a thermodynamically favoured pure YAG phase has been confirmed, regardless of the applied heat‐treatment conditions. Although incomplete, Ce3+ introduction into the host matrix has been detected by XRPD and luminescence measurements.

Optimal antigen retrieval for ethanol‐fixed cytologic smears

Antigen retrieval, a crucial technique for immunostaining, is often carried out on formalin-fixed, paraffin-embedded (FFPE) tissue sections. The role of antigen retrieval in immunostaining of ethanol-fixed smears remains unclear. The authors evaluated the effects of 2 common antigen retrieval procedures, heat-induced antigen retrieval and protease-induced antigen retrieval, for immunostaining using a broad panel of antibodies. Papanicolaou-stained ethanol-fixed smears from 36 surgical specimens were immunostained with 43 antibodies. Three widely used heat-induced antigen retrieval solutions, namely, citrate buffer (pH 6.0 and pH 7.0) and ethylenediaminetetraacetic acid solution (pH 8.0) for heat-induced antigen retrieval, and pronase were used. The staining results were compared between the ethanol-fixed smears and the corresponding FFPE tissue sections. Heat-induced antigen retrieval was essential for all the 9 antibodies examined against nuclear antigens, and for 7 of 26 antibodies against cytoplasmic and cell membrane antigens. Superior results were obtained using lower-pH heat-induced antigen retrieval solutions for ethanol-fixed smears than was the case for FFPE tissue sections; use of citrate buffer (pH 6.0) was optimal for most antibodies. For 17 antibodies against cytoplasmic/cell membrane antigens, satisfactory results were obtained even without antigen retrieval on the ethanol-fixed smears, whereas antigen retrieval was necessary for detection on the FFPE tissue sections. Protease-induced antigen retrieval frequently exerted deleterious effects on ethanol-fixed smears. Despite antigen retrieval, detection of 2 lymphocytic markers failed on ethanol-fixed smears. This limitation was overcome by heat-induced antigen retrieval on formalin vapor-fixed smears. In ethanol-fixed smears, most of the antibodies can be immunostained successfully without antigen retrieval treatment or mild heat-induced antigen retrieval using citrate buffer (pH 6.0). The optimal antigen retrieval condition for each antibody must be individually determined.