Thiocyanate Solutions Research Articles

Application of artificial neural network to simultaneous potentiometric determination of silver(I), mercury(II) and copper(II) ions by an unmodified carbon paste electrode

The response characteristics and selectivity coefficients of an unmodified carbon paste electrode (CPEs) towards Ag+, Cu2+ and Hg2+ were evaluated. The electrode was used as an indicator electrode for the simultaneous determination of the three metal ions in their mixtures via potentiometric titration with a standard thiocyanate solution. A three-layered feed-forward artificial neural network (ANN) trained by back-propagation learning algorithm was used to model the complex non-linear relationship between the concentration of silver, copper and mercury in their different mixtures and the potential of solution at different volumes of the added titrant. The network architecture and parameters were optimized to give low prediction errors. The optimized networks were able to precisely predict the concentrations of the three cations in synthetic mixtures.

Application of artificial neural network to simultaneous potentiometric determination of silver(I), mercury(II) and copper(II) ions by an unmodified carbon paste electrode

The response characteristics and selectivity coefficients of an unmodified carbon paste electrode (CPEs) towards Ag+, Cu2+ and Hg2+ were evaluated. The electrode was used as an indicator electrode for the simultaneous determination of the three metal ions in their mixtures via potentiometric titration with a standard thiocyanate solution. A three-layered feed-forward artificial neural network (ANN) trained by back-propagation learning algorithm was used to model the complex non-linear relationship between the concentration of silver, copper and mercury in their different mixtures and the potential of solution at different volumes of the added titrant. The network architecture and parameters were optimized to give low prediction errors. The optimized networks were able to precisely predict the concentrations of the three cations in synthetic mixtures.

Detection and differentiation between cracking processes based on electrochemical and mechanical measurements

Electrochemical voltage and current noise were measured during slow-rate-load-tensile (SRLT) tests on sensitized austenitic stainless steel specimens in a diluted aqueous solution of sodium thiocyanate. Elongation of tensile test specimen was measured also. It has been found that cracking processes caused simultaneous transients of electrochemical voltage and current. Two different types of electrochemical noise transients were observed: sharp transients of short duration (Type I), and smooth fluctuations that lasted over a much longer period (Type II). Based on the expected cracking mechanism (the slip-dissolution model) and visual observations, it is believed that the sharp transients were generated by the propagation of cracks by mechanical fractures of material ligaments, whereas the smooth fluctuations were generated by propagation of crack via intergranular dissolution. Additional analysis of current transients was performed, and the ratio between the current amplitudes and the charge assessed. Both types of transients were distinguished from the results of this analysis. Based on that, it can be assumed that during the cracking processes which generate Type I transients only the surface of the specimen reacts, whereas in the case of Type II transients the reactions occur inside the specimen.

Calculated phase diagrams for cellulose/ammonia/ammonium thiocyanate solutions in comparison to experimental results

Flory's lattice theory for rigid rod molecules and Kuhn chains is used to calculate phase diagrams for cellulose/ammonia/ammonium thiocyanate solutions. Persistence length values measured by light scattering and reported previously are used as rod length values. Variations in the phase diagram based on varying rod length/solvent composition and cellulose molecular weight are explored. Spinodal curves are calculated in a region of the phase diagram predicting phase separation between two anisotropic solutions. Finally, calculated phase diagrams are compared to published data for the system. Discrepancies between theory and data may be accounted for by soft interactions between cellulose molecules and solvent which are not incorporated into the lattice theory.

Electrical Conductances and Viscosities of Tetrabutylammonium Thiocyanate in Acetonitrile in the Temperature Range 25–45 °C

Abstract The electrical conductances and viscosities of the solutions of tetrabutylammonium thiocyanate (Bu4NCNS) in acetonitrile have been reported at 25, 30, 35, 40 and 45 °C. The conductance data have been analyzed by the 1978 Fuoss conductance-concentration equation in terms of the limiting molar conductance (Λ0), the association constant (K Λ) and the association diameter (R). The viscosity data have been analyzed by the Jones–Dole equation for the associated electrolytes to evaluate the viscosity B-coefficients of the electrolyte. These data have also been analyzed by the transition-state treatment to obtain the contribution of the solutes to the free energy of activation for viscous flow of the solution. The ionic contributions to the limiting molar conductance (Λ0), the viscosity B-coefficient and the free energy of activation for viscous flow have been estimated using the “reference electrolyte” tetrabutylammonium tetraphenylborate (Bu4NBPh4). Slight ionic association was always found for this salt in this solvent medium. The tetrabutylammonium ion is found to be unsolvated whereas the thiocyanate ion undergoes solvation in acetonitrile in the temperature range investigated here.

Optimisation of mercury film deposition on glassy carbon electrodes: evaluation of the combined effects of pH, thiocyanate ion and deposition potential

The combined effects of pH, thiocyanate ion and deposition potential in the characteristics of thin mercury film electrodes plated on glassy carbon surfaces are evaluated. Charges of deposited mercury are used as an experimental parameter for the estimation of the effectiveness of the mercury deposition procedure. The sensitivity of the anodic stripping voltammetry (ASV) method for the determination of lead at in situ and at ex situ formed thin mercury films are also examined. It was concluded that, in acidic solutions (pH 2.5–5.7) and fairly negative deposition potentials, e.g. −1.3 to −1.5 V, thiocyanate ion promotes the formation of the mercury film, in respect both to the amount of deposited mercury and to the mercury deposition rate. Also, the mercury coatings produced in thiocyanate solutions are more homogeneous, as depicted by microscopic examinations. In the presence of thiocyanate there is no obvious advantage of using high concentrations of mercury and/or high deposition times for the in situ and ex situ preparation of the mercury film electrodes. The optimised thin mercury film electrode ex situ prepared in a 5.0 mM thiocyanate solution of pH 3.4 was successfully applied to the ASV determination of lead and copper in acidified seawater (pH 2). The limit of detection (3 σ) was 6×10 −11 M for lead and 2×10 −10 M for copper for a deposition time of 5 min. Relative standard deviations (R.S.D.s) of <1.2% were obtained for determinations at the nanomolar of concentration level.

Use of the molybdenum–thiocyanate–rhodamine 6G ternary complex for spectrophotometric molybdenum determination without extraction

A modified thiocyanate method without extraction by using rhodamine 6G as a secondary ligand was developed. Molybdenum in 1.0×10−2M HCl, after the addition of ascorbic acid, was heated for 10min in a 90°C water bath for reduction. Suitable amounts of glycerine, Triton X-100, rhodamine 6G solutions and 2+1 (v/v) 9M H2SO4+3M KHSO4 were added in this order. This solution was allowed to cool to room temperature and the absorbance at 570nm was measured against a reagent blank 45min after the addition of thiocyanate solution and the second aliquot of Triton X-100 solution. The complex was stable for at least 4h, the order of reagent addition was important, and thiocyanate should be in large excess. Beer’s law was obeyed over the range 0.9×10−6 to 1.1×10−5M Mo with the molar absorptivity being 1.1×105lmol−1cm−1. The R.S.D. for the determination of 0.7mgMol−1 was 1.83% (n=8). Possible interferences of various cations and anions on molybdenum determination were studied. The proposed method was applied to the determination of molybdenum in a dental alloy, Wiron 99.

The Structure and Thermodynamics of Ion Association and Solvation of Some Thiocyanates and Nitrates in 2-Methoxyethanol Studied by Conductometry and FTIR Spectroscopy

Precise measurements on electrical conductances and Fourier transform infrared spectra (FTIR) of solutions of potassium thiocyanate (KCNS), ammonium thiocyanate (NH4CNS), sodium nitrate (NaNO3), an...

Propofol inhibits volume-sensitive chloride channels in human coronary artery smooth muscle cells.

Volume-sensitive chloride channels (VSCC) play an important role in regulation of cell volume and electrical activity. Activation of vascular smooth muscle VSCC causes smooth muscle depolarization and contraction. We investigated the effects of propofol on VSCC in cultured human coronary artery smooth muscle cells by using the chloride-sensitive dye 6-methoxy-N-ethylquinolinium (MEQ). To activate VSCC, cells were superfused for 2 min with hypotonic gluconate solutions and then potassium thiocyanate solution. The percentage reduction in MEQ fluorescence during 60 s in the presence of potassium thiocyanate was measured and used as an index of VSCC activity. 5-Nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), a well characterized chloride channel blocker, and propofol were dissolved in hypotonic gluconate solution to test their effect on VSCC activity. The reduction in fluorescence was inversely related to osmolality, indicating that activation of VSCC is osmolality dependent. Hypotonic gluconate solution (210 mOsm/kg H(2)O) reduced fluorescence by 38.9% +/- 2.6% of the baseline value. The reduction in fluorescence was dose-dependently inhibited by NPPB. Propofol at 0.3, 1, 3, 10, 30, and 100 micro g/mL significantly inhibited the reduction in fluorescence to 23.6% +/- 4.8%, 19.7% +/- 7.4%, 18.2% +/- 3.5%, 17.6% +/- 5.0%, 15.8% +/- 3.1%, and 10.3% +/- 3.9% of the baseline value, respectively. Our results indicate that propofol inhibits VSCC in a dose-dependent manner in human coronary artery smooth muscle cells.

In situ infrared spectroelectrochemical studies of the corrosion of a nickel electrode as a function of applied potential in cyanate, thiocyanate, and selenocyanate solutions

This paper presents the first subtractively normalized interfacial Fourier transform infrared spectroscopic (SNIFTIRS) study of the corrosion system Ni/XCN − (X=O, S, Se), pH 11, [XCN −]=0.05 mol L −1, supporting electrolyte 0.1 mol L −1 KNO 3, for a nickel electrode as a function of applied potential. Cyclic voltammograms, in situ infrared spectra, and current–potential data (recorded while the infrared spectral acquisition was in progress) were recorded for a nickel electrode in a three-electrode thin-layer cell containing the pseudohalides OCN −, SCN −, or SeCN − ions at pH 11 in a supporting electrolyte of KNO 3. In general, the data showed that all of the pseudohalide ions studied caused corrosion of the nickel electrode by forming the respective nickel–pseudohalide complex ion species as the potential was stepped anodically. Two of the ions, SCN − and SeCN −, caused surface modifications to the electrode which influenced the electrochemical reactions with respect to CO 2 formation. The Ni/SeCN − system, for instance, exhibited signs of instability during the spectroelectrochemical experiment, red-brown coatings observed on the electrode caused by the decomposition of the selenocyanate ion to colloidally dispersed elemental selenium. The selenium coated the electrode, hence modifying the surface and consequently the electrochemistry, by causing the “early” appearance of CO 2-associated IR peaks in SNIFTIRS spectra recorded from the electrode system at potentials lower than those for the Ni/OCN − system. In contrast, CO 2 formation at the electrode surface was not observed in the Ni/SCN − system, which was likely to have been caused by nickel sulfide poisoning of the electrode surface. In the Ni/SCN − and Ni/SeCN − systems, IR spectra also indicated the buildup of Ni(SCN) 2 and Ni(SeCN) 2 salts in the thin layer by the appearance of a peak at ca. 2165 cm −1 at anodic values of the applied potential.

Specific determination of ferbam residues in fog-water

A specific method for the determination of a fungicide, i.e. iron(III) dimethyldithiocarbamate (ferbam) in fog-water samples is described. The method is based on the releasing of equivalent amount of iron from the fungicide and subsequently determination by spectrophotometrically or by flame-atomic absorption spectrometrically (flame-AAS). The fungicide was extracted with chloroform/toluene from the samples and digested with nitric acid. For spectrophotometric determination, the solution was then treated with ammonium thiocyanate solution in presence of the surfactants and absorbance was measured at 475 nm. Whereas, the digested solution was directly applied for flame-AAS determination of ferbam. The molar absorptivity in terms of ferbam was determined to be (3.49)×10 4 l mol −1 cm −1. The detection limits for spectrophotometric and flame-AAS methods were calculated to be 62 and 111 ppb ferbam (R.S.D. <1 and <3%), respectively. Whereas, the optimum concentration ranges for the analysis of ferbam are 4–120 and 1.5–55 μg in final volume, respectively. The methods are freed from interference of almost all ions [including Fe(II) and Fe(III)], which can commonly associate with ferbam in fog-water. The methods have been successfully applied to fog samples collected from agriculture sites of Raipur (central India).

Room-temperature hybridization of target DNA with microarrays in concentrated solutions of guanidine thiocyanate.

BioTechniquesVol. 34, No. 6 BenchmarkOpen AccessRoom-Temperature Hybridization of Target DNA with Microarrays in Concentrated Solutions of Guanidine ThiocyanateS.-C. Tao, Y. Li, Y.-H. Liu, X.-M. Ma & J. ChengS.-C. TaoTsinghua UniversityNational Engineering Research Center for Beijing Biochip Technology, Beijing, ChinaSearch for more papers by this author, Y. LiTsinghua UniversityNational Engineering Research Center for Beijing Biochip Technology, Beijing, ChinaSearch for more papers by this author, Y.-H. LiuNational Engineering Research Center for Beijing Biochip Technology, Beijing, ChinaSearch for more papers by this author, X.-M. MaNational Engineering Research Center for Beijing Biochip Technology, Beijing, ChinaSearch for more papers by this author & J. Cheng*Address correspondence to: Dr. Jing Cheng,National Engineering Research Center for Beijing Biochip Technology (NERCBBT), Jia 2# Qinghua West Road, Haidian District, Beijing 100084, China. e-mail: E-mail Address: jcheng@tsinghua.edu.cnTsinghua UniversityNational Engineering Research Center for Beijing Biochip Technology, Beijing, ChinaSearch for more papers by this authorPublished Online:24 Sep 2018https://doi.org/10.2144/03346mt01AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInReddit "Room-Temperature Hybridization of Target DNA with Microarrays in Concentrated Solutions of Guanidine Thiocyanate." , 34(6), pp. 1260–1262FiguresReferencesRelatedDetailsCited ByProficiency Testing of Epidermal Growth Factor Receptor Mutations Detection in Saliva Using Spectrum Saliva Collector (SDNA-1000) and Preservative Solution Detected by Electric Field-Induced Release and MeasurementBiopreservation and Biobanking, Vol. 20, No. 5Development of a Linker-Mediated Immunoassay Using Chemically Transitioned Nanosensors7 February 2020 | Analytical Chemistry, Vol. 92, No. 5Progress Towards a Real-time PCR Assay for the Simultaneous Detection of Clavibacter michiganensis subsp. michiganensis and Pepino mosaic virus in Tomato Seed28 April 2012 | Journal of Phytopathology, Vol. 160, No. 7-8Determination for Enterobacter cloacae based on a europium ternary complex labeled DNA probeSpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Vol. 82, No. 1The design and application of DNA chips for early detection of SARS-CoV from clinical samplesJournal of Clinical Virology, Vol. 33, No. 2Integrated microsystem for dielectrophoretic cell concentration and genetic detectionLab on a Chip, Vol. 5, No. 10Current Awareness on Comparative and Functional GenomicsComparative and Functional Genomics, Vol. 4, No. 6 Vol. 34, No. 6 Follow us on social media for the latest updates Metrics Downloaded 354 times History Published online 24 September 2018 Published in print June 2003 Information© 2018 Author(s)PDF download

Stress corrosion cracking and hydrogen embrittlement susceptibility of an eutectoid steel employed in prestressed concrete

The stress corrosion and hydrogen embrittlement behavior of AISI 1080 steel employed in concrete prestressing tendons was studied with different experimental techniques. A simulated concrete pore solution, with and without contaminants such as chloride, sulfate and thiocyanate ions was used. For comparison purposes the standard 20% ammonium thiocyanate solution was also employed. Polarization curves, slow strain rate tests and fracture mechanics tests were used to evaluate the influence of parameters such as potential, temperature (between 0 and 100 °C), and tempering temperature of the steel. The results have shown that the fracture mechanism of the stress corrosion cracking process is associated with hydrogen action.

Isopiestic determination of osmotic coefficients and evaluation of vapor pressures for solutions of sodium bromide and sodium thiocyanate in methanal at 25 °C

The osmotic coefficients of sodium bromide and sodium thiocyanate in methanol have been measured by the isopiestic method at 25 °C. Sodium iodide was used as isopiestic standard for the calculation of osmotic coefficients. The molality ranges covered in this study correspond to about 0.17–1.56 mol·Kg −1 for NaBr and 0.15–3.43 mol·kg −1 for NaSCN. Experimental osmotic coefficient data are reliably represented by the Pitzer model (with and without the β (2) term), self-consistent local composition model (SCLC) and modified self-consistent local composition model (MSCLC). The parameters from the fit were used to calculate the vapor pressures. The osmotic coefficient data are successfully correlated with these models, and the models provide reliable predication of vapor pressures.

Thiocyanate Wet Oxidation

Aqueous solutions of thiocyanate were oxidized in a semi-batch reactor at temperatures between 170 and 210 °C and system total pressures ranging from 70 to 100 atm. The initial pH of the solution was set at 12, while initial concentrations have ranged between 20 and 1000 ppm according to the typical concentrations of thiocyanate-containing wastewater. The kinetic data discussion was based on the establishment of a kinetic regime control that guaranteed the validity of the experimental data and that oxygen excess was assured for all the runs. An attempt to establish a thiocyanate wet oxidation pathway has been made on the basis of the reaction intermediates and final oxidation products identified during the experimental work. SO42- and CO3- have been pointed out as the main final reaction products whereas (SCN)2 and SCNO- are suggested as possible short-life oxidation intermediates. The oxidation reaction results were fitted to a first-order kinetic equation with respect to thiocyanate and to 0.81 with respect to oxygen, with an activation energy of 84.4 kJ mol-1.

Facilitated Transport of Gold from Cyanide or Chloride Media by Cyanex 923

The commercially available extractant Cyanex 923 (phosphine oxides mixture) was studied to be applied in the carrier-facilitated transport of gold, from either cyanide or chloride aqueous media, across a polymer-immobilized liquid membrane (PILM). is transported from alkaline pH values. The presence of lithium salts (and the respective counter anion) in the media improves the transport, whereas the organic diluent seems not to influence the metal permeability. Water can be used effectively, as receiving phase, for the present system. In chloride media, the carrier is able to transport gold(III), increasing the permeability as the initial HCl concentration is increased (up to5×10−1 M HCl). This permeability is dependent on the respective organic diluent, being the metal flux independent at higher initial gold concentrations but metal dependent at lower gold concentrations in the feed phase. Sodium thiocyanate solutions can be used effectively as receiving phase in this media. From the experimental data, the mass-transfer coefficient in the aqueous feed phase and the thickness of the aqueous boundary layer were calculated for both, cyanide and chloride, aqueous media.

Adsorption profile of preheated Cr(III)-SCN complexes on polyurethane foam

The accumulation of preheated chromium(III)-thiocyanate complexes onto polyurethane foam (PUF) has been studied. The maximum sorption of Cr(III) (7.01.10-5M) is occurred at pH 2 from 1.2M thiocyanate solution in 10 minute agitation time using 7.25 mg/ml PUF. The sorption data have been investigated by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters 1/n = 0.31 and of KF = 9.7.10-4 mol.g-1, Langmuir constants M = 7.03.10-5 mol.g-1 and of b = 1.5.105 l.mol-1 and of D-R constants, Cm = 1.91.10-4 mol.g-1, affinity coefficient b = -0.0023 mol2.kJ-2 and sorption energy E = 14.7 kJ.mol-1 have been evaluated. Thermodynamic parameters of enthalpy, entropy and Gibbs free energy suggest the endothermic and spontaneous adsorption of Cr(III)-SCN complex onto PUF at higher temperature. The influence of common anions and cations on the accumulation of chromium-thiocyanate on PUF and possible sorption mechanism of [Cr(SCN)4]- species on PUF is discussed.

Viscometric Properties of Solutions of Amylose and Amylopectin in Aqueous Potassium Thiocyanate

Solutions of commercial potato amylose (1.65%, w/v) in dimethyl sulfoxide (DMSO) /water mixtures formed gels on standing when the water content was equal to or greater than 60% (w/v). These gels did not form when the water was replaced with aqueous potassium thiocyanate solution (KSCN, 2 mol/L). Commercial amylose did not dissolve completely in aqueous KSCN, unlike commercial potato and corn amylopectins, which formed more stable solutions than those in water alone. Solutions of amylopectin in mixtures of DMSO and aqueous KSCN showed a maximum relative viscosity (flow viscometer) at 80% (v/v) DMSO, like those in DMSO/water. Solutions of amylopectin in 25% (v/v) DMSO/75% (v/v) aqueous KSCN (2 mol/L) could be used for estimation of molecular weight by flow viscometry using the Mark-Houwink-Sakurada Equation. Sigma corn amylopectin gave a weight average molecular weight of 12.1 x 106, lower than that obtained using DMSO alone, and likely to be due to a lower degree of hydrogen bonding in the presence of KSCN, consistent with its chaotropic effect. This effect was also reinforced by the observation that formation of the amylose/iodine complex is inhibited by KSCN at concentrations as low as 0.2 mol/L.

Flow-injection simultaneous determination of iron(III) and copper(II) and of iron(III) and palladium(II) based on photochemical reactions of thiocyanato-complexes

The flow injection analysis systems have been developed for the simultaneous determination of iron(III) and copper(II) and of iron(III) and palladium(II) based on the photochemical reactions of their thiocyanato-complexes. In the first system, a sample solution was injected in to nitric acid solution and mixed with ammonium thiocyanate solution, followed by spectrophotometric monitoring of the thiocyanato-complexes formed. Another aliquot of the same sample solution was injected and the thiocyanato-complexes formed in the same way were irradiated by UV light before spectrophotometric monitoring. In another system, the absorbance of thiocyanato-complexes formed by each sample injection was monitored with two flow cells aligned with the same optical path before and after UV irradiation. The difference in the extent of photochemical decomposition of the thiocyanato-complexes enabled simultaneous determinations of iron(III) and copper(II) and of iron(III) and palladium(II) at levels of several μg ml −1 to some tens μg ml −1 in their admixtures. Sample throughputs are 40 and 20 h −1 by the former and latter systems, respectively.

Effects of lipids on elastin's viscoelastic properties.

Sodium dodecyl sulfate (SDS) was used as a model lipid to identify the molecular basis of possible lipid-induced changes in the viscoelastic behavior of arterial elastin. The chemical composition of the elastin network and the interfibrillar space was calculated from the chemical content of the elastin sample and its swelling behavior. Viscoelastic behavior was measured in aqueous SDS and in SDS plus 1 M sucrose, a deswelling agent. Viscoelastic behavior was also measured in sucrose and potassium thiocyanate solutions to identify the effects of swelling and of changes in network composition exclusive of any direct SDS effects. The hydration of the elastin network decreased at low SDS levels and increased at higher SDS levels. The elastin was stiffer in the dehydrated network and less stiff in the hydrated network. However, once the degree of hydration exceeded that of elastin in pure water, no further decrease in stiffness was obtained despite continued increase in swelling. The stiffness of the network could be accounted for entirely by changes in network hydration. There was no evidence that SDS had any effect on elastin's conformation. We predict that arterial lipids will interact with elastin in a similar way and will have only small effects on elastin's viscoelastic behavior.