Solutions Of Ternary Mixtures Research Articles

Sugars’ Quantifications Using a Potentiometric Electronic Tongue with Cross-Selective Sensors: Influence of an Ionic Background

Glucose, fructose and sucrose are sugars with known physiological effects, and their consumption has impact on the human health, also having an important effect on food sensory attributes. The analytical methods routinely used for identification and quantification of sugars in foods, like liquid chromatography and visible spectrophotometry have several disadvantages, like longer analysis times, high consumption of chemicals and the need for pretreatments of samples. To overcome these drawbacks, in this work, a potentiometric electronic tongue built with two identical multi-sensor systems of 20 cross-selectivity polymeric sensors, coupled with multivariate calibration with feature selection (a simulated annealing algorithm) was applied to quantify glucose, fructose and sucrose, and the total content of sugars as well. Standard solutions of ternary mixtures of the three sugars were used for multivariate calibration purposes, according to an orthogonal experimental design (multilevel fractional factorial design) with or without ionic background (KCl solution). The quantitative models’ predictive performance was evaluated by cross-validation with K-folds (internal validation) using selected data for training (selected with the K-means algorithm) and by external validation using test data. Overall, satisfactory predictive quantifications were achieved for all sugars and total sugar content based on subsets comprising 16 or 17 sensors. The test data allowed us to compare models’ predictions values and the respective sugar experimental values, showing slopes varying between 0.95 and 1.03, intercept values statistically equal to zero (p-value ≥ 0.05) and determination coefficients equal to or greater than 0.986. No significant differences were found between the predictive performances for the quantification of sugars using synthetic solutions with or without KCl (1 mol L−1), although the adjustment of the ionic background allowed a better homogenization of the solution’s matrix and probably contributed to an enhanced confidence in the analytical work across all of the calibration working range.

Simultaneous determination of dihydroxybenzene isomers at nitrogen-doped graphene surface using fast Fourier transform square wave voltammetry and multivariate calibration

In this paper, a highly sensitive electrochemical method, which is based on the combination of fast Fourier transform square wave voltammetry and multivariate calibration techniques, was developed for simultaneous determination of dihydroxybenzene positional isomers, including catechol, hydroquinone, and resorcinol, in environmental samples. An electrochemical sensor was constructed by the deposition of nitrogen-doped graphene on a glassy carbon electrode to apply as a new approach for the multicomponent analysis. Partial least squares was applied, as a multivariate calibration method, to deconvolute the highly overlapping electrochemical signals from the analytes. Using the simplex experimental design with the degree of 4, 19 ternary mixture solutions of the cited analytes were prepared in the established linear ranges of the analytes. The developed multivariate model was validated by predicting the concentration of 8 independent solutions. The root mean square error values of validation values were between 0.04230 and 0.06549 μM, respectively. The applicability of the proposed method was checked using water samples (collected from both the surface and waste water) and human urine, and the obtained recovery values were between 89.3 and 107.1%. The limits of detection and relative standard deviations for catechol, hydroquinone, and resorcinol were 0.046, 0.046, and 0.045 μM, and 3.6, 3.4 and 3% (N = 5), respectively.

Simultaneous determination of ascorbic acid, uric acid and dopamine at modified electrode based on hybrid nickel hexacyanoferrate/poly(1,5-diaminonaphthalene)

A novel modified electrode was fabricated by a mixed-valent nickel hexacyanoferrate (NiHCF) and poly 1,5-diaminonaphthalene (PDAN) hybrid at glassy carbon (GC) electrode. The obtained NiHCF/PDAN/GC modified electrode was characterized using cyclic voltammetry (CV) technique and scanning electron microscope (SEM). This electrode showed excellent catalytic properties toward the electrooxidation of ascorbic acid (A.A), dopamine (D.A) and uric acid (U.A) in 0.1 M NaCl solution using CV and square wave voltammetry (SWV) techniques. The NiHCF/PDAN/GC modified electrode exhibits high sensitivity, selectivity and stability making it a suitable sensor for the simultaneous detection of A.A, U.A and D.A in single and ternary mixture solutions. Different analytical parameters such as low detection limit (LOD), low quantification limit, correlation coefficient (R) and linear dynamic range were reported and discussed. The NiHCF/PDAN/GC modified electrode exhibits linear responses to A.A, D.A and U.A in the range 600–1000, 600–1000 and 600–1000 µM, respectively. The LOD for A.A, D.A and U.A were 0.036, 0.034 and 0.037 µM, respectively. The analytical behavior of this sensor had been evaluated for the detection of A.A and U.A in human serum and urine samples with satisfactory results.

Interfacial Properties of Alkylbenzene Sulfonates Ternary Mixtures

Abstract Dynamic interfacial tension (IFT) behaviors of dialkylbenzene sulfonate (DAS)/heavy alkylbenzene sulfonate (HABS)/dodecylbenzene sulfonate (LAS) ternary mixture solutions against a homologous series of alkanes were studied. On the basis of our experimental results, one can find that the lipophilic ability of DAS was stronger than that of HABS. At the lower content of LAS, the ternary system was oil soluble; at the higher content of LAS, the ternary system was water soluble. An IFT in the 10– 3 mN/m range can be obtained for the ternary system against long-chain alkanes (decane, dodecane) under the condition that the content of LAS was 30 %. A dynamic IFT of 10– 4 mN/m order of magnitude was observed against decane. The hydrophilic-lipophilic ability of the surfactant plays an important role in dynamic IFT behavior. With increasing content of LAS, the alkane carbon number of ternary mixture solutions for producing the lower IFT had a tendency to lower.

The Design and Operation of Ultra-Sensitive and Tunable Radio-Frequency Interferometers.

Dielectric spectroscopy (DS) is an important technique for scientific and technological investigations in various areas. DS sensitivity and operating frequency ranges are critical for many applications, including lab-on-chip development where sample volumes are small with a wide range of dynamic processes to probe. In this work, we present the design and operation considerations of radio-frequency (RF) interferometers that are based on power-dividers (PDs) and quadrature-hybrids (QHs). Such interferometers are proposed to address the sensitivity and frequency tuning challenges of current DS techniques. Verified algorithms together with mathematical models are presented to quantify material properties from scattering parameters for three common transmission line sensing structures, i.e., coplanar waveguides (CPWs), conductor-backed CPWs, and microstrip lines. A high-sensitivity and stable QH-based interferometer is demonstrated by measuring glucose-water solution at a concentration level that is ten times lower than some recent RF sensors while our sample volume is ~1 nL. Composition analysis of ternary mixture solutions are also demonstrated with a PD-based interferometer. Further work is needed to address issues like system automation, model improvement at high frequencies, and interferometer scaling.

Correlation between wetting, adhesion and adsorption in the polymer–aqueous solutions of ternary surfactant mixtures–air systems

The correlation between the wettability of polymers and adsorption of ternary mixtures including CTAB, TX-100 and TX-114 at the polymer–aqueous solution interface as well as the adhesion of aqueous solution of these mixtures to apolar polytetrafluoroethylene (PTFE), monopolar polymethyl methacrylate (PMMA) and nylon 6 was considered on the basis of the contact angle measurements and the literature data of the solutions surface tension. From these considerations it appeared that the efficiency and effectiveness of the adsorption at the PTFE–water interface are comparable to those at the water–air one, but for the PMMA–water and nylon 6–water interfaces they are lower than those for the water–air one for a given series of solutions. The efficiency and effectiveness are reflected in the composition of the mixed monolayer at the polymer–solution interface which even for the PTFE–solution interface is somewhat different from the water–air interface. The properties of the mixed monolayer at these interfaces influence the critical surface tension of polymer wetting which for PTFE is somewhat higher but for PMMA and nylon 6 considerably lower than their surface tension. From these considerations it also appeared that the work of adhesion of aqueous solutions of ternary mixtures of surfactants to the PTFE surface does not depend on the composition and concentration of solution contrary to PMMA and nylon 6. The adhesion work of these solutions to the PMMA and nylon 6 surface can be determined on the basis of van Oss et al. and Neumann et al. equations.

Work of adhesion and activity of aqueous solutions of ternary mixtures of hydrocarbon and fluorocarbon nonionic surfactants at the water–air and polymer–water interfaces

The values of the surface tension and contact angle on the polytetrafluoroethylene surface (PTFE) of aqueous solutions of the ternary mixtures of hydrocarbon surfactants, TX100 and TX165, and fluorocarbon FSN100 at different mole fractions of surfactants in the bulk phase were applied for the studies of the correlation between the adsorption of surfactants at the solution–air and polymer–solution interfaces, the work of adhesion determined from the Young–Dupree equation, the parameter of the intermolecular interactions and the spreading coefficient of aqueous solutions of the studied mixtures on the PTFE surface. For this purpose the values of the total mole fraction and activity of surfactants at the polymer–solution interface obtained from the Sprow and Prausnitz equation were compared to those at the solution–air one. Also on the basis of the mole fraction of the particular surfactants at the PTFE–solution and water–air interface and on the assumption of the additivity of the adhesion work, the work of adhesion of the fluorocarbon tail to the PTFE surface as well as the Lifshitz–van der Waals component of the PTFE surface tension were calculated.

Wetting and Adsorption Properties of Aqueous Solutions of Ternary Mixtures of Hydrocarbon and Fluorocarbon Nonionic Surfactants in PTFE-Solution–Air Systems

The surface tensions and contact angles of aqueous solutions of ternary mixtures of hydrocarbon, TX100 and TX165, and fluorocarbon, FSN100, surfactants at different mole fractions in the bulk phase on a poly(tetrafluoroethylene) (PTFE) surface were studied. The measured values were used in the Young equation for calculations of the polymer–solution interfacial tension in two ways, first, assuming that the surface tension of PTFE is constant and, second, assuming that this tension is not constant and is equal to the value determined for FSN100 at a given concentration. Next, the Gibbs surface excess concentrations of the studied mixtures at the polymer–solution interface were calculated and compared to the corresponding values at the solution–air interface. Also, the critical surface tension of polymer wetting was obtained from the relationship between the adhesion tension and the surface tension of aqueous solutions of the studied mixtures and then related to the adsorption of the surfactants at the water–air and PTFE–water interfaces.

Studies on macromolecular interactions in ternary mixtures of konjac glucomannan, xanthan gum and sodium alginate

Covalent and non-covalent macromolecular interactions were studied in the proprietary commercial product, PGX ® (PolyGlycopleX ®) which is manufactured from konjac glucomannan, xanthan gum and sodium alginate using a proprietary manufacturing process (EnviroSimplex ®). Analytical techniques established the absence of changes in primary covalent structure of any of the component polysaccharides which may have occurred when the product was manufactured. However, non-covalent interactions between the polysaccharides were apparent in aqueous solutions of proprietary ternary mixtures by comparing their flow behaviour with those of unmixed controls. The interactions indicated by the flow behaviour confirmed those observed in the sedimentation behaviour, published earlier (Abdelhameed, A. S., Ang, S., Morris, G. A., Smith, I., Lawson, C., Gahler, R., et al. (2010). Carbohydrate Polymers, 81, 145–148). Non-covalent macromolecular interactions between konjac glucomannan and xanthan gum are already known in binary mixtures but the flow behaviour of solutions of laboratory-prepared ternary powder mixtures with variable sodium alginate content was consistent with a ternary macromolecular interaction involving sodium alginate at below 5% but this was significantly enhanced by heat treating the solutions when the sodium alginate content exceeded 5%. Sedimentation coefficient distribution analysis from analytical ultracentrifugation supports these observations showing a clear shift to higher sedimentation coefficients in the heat-treated solutions of ternary mixtures at sodium alginate concentrations >8%, and over a greater range compared with unheated material. Calcium ion addition failed to precipitate calcium alginate from solutions of PGX ® (containing all three polysaccharides) but precipitates were obtained from solutions of binary mixtures prepared with either konjac glucomannan or xanthan gum plus sodium alginate. The results are consistent with an interaction between a konjac glucomannan–xanthan gum complex and sodium alginate to form a new, ternary complex.

A Study of the Interactions of Ternary Surfactant Systems at the Water−Air Interface

Surface tension measurements were carried out for the systems containing ternary mixtures of cetyltrimethylammonium bromide (CTAB) and p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100) and Triton X-165 (TX165). The aqueous solution of ternary surfactant mixtures were prepared by adding the third surfactant to the binary mixture of the surfactants where the synergetic effect in the reduction of the surface tension of water were determined to compare the influence of the third surfactants on the adsorption of this binary mixture at the water-air interface. The obtained results and calculations indicate that the synergetic effect in the reduction of the surface tension of water was deepened after adding the third surfactant to the binary mixture at the composition at which this effect was observed. The best synergetic effect in the gamma(LV) reduction was determined on the basis of the values of the molecular interaction parameter for aqueous solutions of ternary mixtures of CTAB+TX165 (alpha CTAB = 0.2) (gamma(LV) = 50 mN/m, C = 4.3 x 10(-5) M) +TX100 (C=10(8)-10(-2) M).

Quenching of fluorescence of Rhodamine 610 in binary and ternary mixture solutions

The sensitized fluorescence emission from bimixtures, Coumarin 500 (donor) + Rhodamine 610 (acceptor) and Rhodamine 610 (donor) + Nile Blue 590 (acceptor) and also from the ternary mixture, Coumarin 500 (donor) + Rhodamine 610 (inter mediator) + Nile Blue 590 (acceptor), have been measured as a function of dye concentration and excitation wavelength using a fluorescence spectrophotometer. The spectroscopic parameters for the bimixtures have been estimated from the concentration dependence of the peak fluorescence intensity curves.

A vapor pressure method for the simultaneous determination of standard thermodynamic functions of both solutes in a ternary dilute solution

It is shown that from vapor pressure measurements on dilute solutions of ternary mixtures with one nonvolatile component, the standard free energy of transfer (ΔGt0) of both solutes from water to aqueous binary solvents can be determined simultaneously. The method is most useful in the case of volatile components. ΔGt0 values are discussed in particular in the case of the transfer of tetrahydrofuran, acetone, and acetonitrile from water to aqueous tetrabutylammonium bromide and urea solutions and compared to the case of the transfer of nonpolar solutes to the same aqueous solution. In each case, the free energy of transfer from water to an aqueous solution of a nonpolar molecule was negative, and introduction in that molecule of a polar group caused the free energy of transfer to be considerably less negative.