Polar Solutes Research Articles

System of controlling instruments operating activities of a trade enterprise

Introduction. Scientists have already begun to apply actively controlling in various directions and spheres of activity of the enterprise. There is a need to identify structure of controlling instruments that can be used for trading company operational activity. It will deepen the understanding of controlling essence and will make it easier to implement. The purpose of paper is to identify varieties of controlling instruments operating activities of a trade enterprise. Results. In order to practically use systematic tools for product division functionality, in these own cases. Within the sales department propose to use pricing methods. When canceling marketing activities, they use the following tools: portfolio development methods; potential analysis Pilot method; Porter; benchmarking (the process of comparing objects of one enterprise with similar other objects of other enterprises); analysis of analytical shifts; map of strategic groups. Within the personal staff department, you can use your own strength and effectiveness of staff and motivation systems. In the control department of logistics are silent to create: remains a stock; ABC analysis; XYZ analysis. The grocery department was confident. Open procurement can be ABC analysis; XYZ analysis; known order optimization; confident stock level. Branch of appropriate management using design tools; accounting (management); process cost checking (activity-based costing); a sure fact regarding the life cycle (life cycle cost); direct costing; standard bone; transfer pricing methods; margin analysis; EVA, SVA, limit results analysis; functional-cost analysis, system of operation of operating system of ability; general intellectual ability management system; truth chain analysis; analysis of the chain of creation of additional information; comparison of results in chain actions; system of operational monitoring "plan-fact"; a system that considers the budget and remains important; system of regulatory calculation; analysis analysis; factor analysis; analysis of analytical shifts. All units can be used: PEST analysis; central security management; strategic gaps; analysis of strengths and weaknesses in the enterprise (trying to exploit the weaknesses in the enterprise and maintain the utilized potential potential); goal management system; activity based management (activity based management); system of balanced users; strategic maps; modeling; business process map; scenario method (situational approach to management decisions made in uncertainty. Forecasting the outcome of the situation); scenario method (situational approach to management decisions made in uncertainty. Forecasting the outcome of the situation); expert method; mathematical methods; Monte Carlo method; to divide a person by objects; sensitivity analysis; high efficiency of the unit; outsourcing matrix; control of "weak" signals; observation; cognitive conversation (individual and group); polls (written and oral); CAS polar solutions; experiment (natural and laboratory); testing; self-observation and self-reports. Conclusion. The proposed system of controlling instruments is adopted for the operating activities of a trading enterprise. It let to implement all the main functions of controlling.

A terpyridine luminophore: Synthesis, photophysics and selective metal ion–Mediated hydrogelation

Terpyridine ligands are the fascinating materials for metal co-ordination. A new fluorescent 4-(3,4-dimethoxyphenyl) terpyridine ligand (DMPTP) was synthesized. We have explored the solvent dependent photophysical characteristics and the metal ion mediated hydrogel formation of DMPTP. The optical behavior of DMPTP is studied by UV–Visible, steady state and time resolved fluorescence measurements in different solvents. DMPTP exhibits structured emission in non-polar hexane solution and broad emission in polar DMSO solution. In addition, DMPTP holds a large solvent dependent fluorescence shift. These results indicate DMPTP undergoes intramolecular charge transfer (ICT) in the excited state. The fluorescence lifetimes also corroborated the ICT behavior of DMPTP. Moreover, DMPTP produces hydrogel upon formation of complex with Cu2+ and Zn2+ in 1:1 ratio. The xerogels of Zn2+ and Cu2+complex exhibit fibrous and flake like morphology, respectively. Interestingly, the hydrogel obtained from Zn2+ complex is highly fluorescent and the one obtained from Cu2+ complex is non-fluorescent.

Extraction of Ions from a Polar Solution Using a Surface-Modified Membrane Interface

Field-induced extraction of ions from a polar solution is implemented with the aid of an interface that represents a polymer track membrane with a conducting coating. A time-of-flight spectrum of ions extracted from a KI solution in a water–glycerol mixture is obtained using nanosecond electric-field pulses. Application of the conducting coating allows a significant decrease in the voltage of the extracting pulse and suppression of the effect of secondary processes on the composition of ions generated in a pulsed membrane ion source.

Water channel pore size determines exclusion properties but not solute selectivity

Aquaporins (AQPs) are a ubiquitous family of transmembrane water channel proteins. A subgroup of AQP water channels also facilitates transmembrane diffusion of small, polar solutes. A constriction within the pore, the aromatic/arginine (ar/R) selectivity filter, is thought to control solute permeability: previous studies on single representative water channel proteins suggest narrow channels conduct water, whilst wider channels permit passage of solutes. To assess this model of selectivity, we used mutagenesis, permeability measurements and in silico comparisons of water-specific as well as glycerol-permeable human AQPs. Our studies show that single amino acid substitutions in the selectivity filters of AQP1, AQP4 and AQP3 differentially affect glycerol and urea permeability in an AQP-specific manner. Comparison between in silico-calculated channel cross-sectional areas and in vitro permeability measurements suggests that selectivity filter cross-sectional area predicts urea but not glycerol permeability. Our data show that substrate discrimination in water channels depends on a complex interplay between the solute, pore size, and polarity, and that using single water channel proteins as representative models has led to an underestimation of this complexity.

Incorporating CsPbBr3Nanocrystals into Porous AlO(OH) Matrices to Improve their Stability in Backlit Displays

Currently, the poor stability of inorganic perovskite CsPbX3([Formula: see text], Br, I) nanocrystals restricts their practical application in optoelectronic devices. Therefore, improving the stability of this material remains an urgent task for most researchers. In this study, incorporation of CsPbBr3nanocrystals into porous AlO(OH) matrices through simple in situ synthesis was demonstrated to be an efficient approach for improving the nanocrystal stability. X-ray diffraction (XRD) revealed that the as-obtained product was composed of cubic CsPbBr3nanocrystals and orthorhombic AlO(OH) compounds. In addition, transmission electron microscopy (TEM) revealed that the CsPbBr3nanocrystals were successfully encapsulated by AlO(OH) matrices. The Brunauer–Emmett–Teller (BET) specific surface area was 234.96[Formula: see text]m2g[Formula: see text] for AlO(OH) and 60.08[Formula: see text]m2g[Formula: see text] for the CsPbBr3@AlO(OH) composites. The decrease in surface area could be attributed to the filling of the AlO(OH) pores by the CsPbBr3nanocrystals. Further, the as-prepared composites showed red-shifted emission at 522[Formula: see text]nm and a larger full width at half-maximum (FWHM) as 26[Formula: see text]nm, compared with those of the CsPbBr3nanocrystals with the emission at 517[Formula: see text]nm and FWHM as 17[Formula: see text]nm. More importantly, the emission intensity preserved 67% of the original value after a storage time of 120[Formula: see text]h, but bare CsPbBr3nanocrystals rapidly degraded within only 1[Formula: see text]h in the polar ethanol solution. Finally, a light-emitting diode (LED) device was fabricated by coating the CsPbBr3@AlO(OH) composites and red commercial K2SiF6:Mn[Formula: see text] phosphors on the surface of a blue InGaN chip, covering 96% of National Television Standards Committee. The results indicate that the obtained composites could be promising luminescent materials for backlit displays.

Molecular Interactions and Dielectric Relaxation in the Mixtures of Amines with 2Fluorobenzoic Acid in 1, 4Dioxane

For the present study, the estimation of the static dielectric constants (0), dielectric constant () at an angular frequency and dielectric loss () of methyl, ethyl and propyl amines with 2-fluorobenzoic acid in 1,4-dioxane were carried using Klystron microwave bench at frequency 9.43GHz. Using the dielectric parameters, the overall relaxation time (1) and group rotation relaxation time (2) of the polar solute molecules and average relaxation times (0) were also determined using Higasi and Gopalakrishna method employing Debye’s equations. The obtained results revealed that, out of five different molar ratios, relaxation time () is maximum at 1:1 molar concentration for all the systems due to inter and intramolecular interactions through hydrogen bonding. In addition, the dipole moment, activation viscous flow (f) and dielectric relaxation (f) due to molar free energy also been discussed.

Cholesteryl Hemisuccinate Is Not a Good Replacement for Cholesterol in Lipid Nanodiscs.

Nanodiscs are suitable tools for studies of membrane proteins (MPs) due to their ability to mimic native biological membranes, and several MP structures are solved in nanodiscs. Among the various cell membrane components, cholesterol (CHL) is known to regulate protein function and its concentration can reach up to 50 mol %. However, studies comprising cholesterol are challenging due to its hydrophobic nature, hence, nanodiscs with only a low cholesterol concentration have been studied. To overcome the problem, cholesterol analogs with high solubility in polar solutions are often used, and one of them is cholesteryl hemisuccinate (CHS). Nevertheless, in molecular dynamics (MD) simulation, this is not an obstacle. In this study, we performed MD simulations of nanodiscs containing neutral phosphatidylcholine (POPC) lipids, negatively charged phosphatidylglycerol (POPG) lipids, CHL, or negatively charged cholesterol analog, CHS. Our simulations show that CHS increases the order of lipids in nanodiscs; the effect is, however, weaker than CHL and even smaller in nanodiscs. Furthermore, CHS gathered around scaffold proteins while cholesterol was uniformly distributed in the nanodiscs. Thus, nanodiscs with CHS are heterogeneous and not equivalent to nanodiscs with CHL. Finally, we also observed the increased concentration of POPG near the scaffold proteins, driven by electrostatic interactions. The MD results are experimentally validated using electron paramagnetic resonance spectroscopy. These results show that nanodiscs are, in fact, complex structures not easily comparable with planar lipid bilayers.

Influence of Charge Scaling on the Solvation Properties of Ionic Liquid Solutions.

Scaled-charge force fields (FFs) are widely employed in the simulation of neat ionic liquids (ILs), where the charges on the ions are empirically scaled to approximately account for electronic polarization and/or charge transfer. Such charge scaling has been found to yield significant improvement in liquid-state thermodynamic and dynamic properties (when compared to experiment). However, the mean field approximation inherent in charge scaling becomes suspect when applied to IL mixtures or solutions. In this work, we simulate solutions of IL with various nonpolar and polar gas solutes and compare results of charge-scaled and polarizable FFs to experiment. Our results demonstrate that scaling of the Coulomb interaction inherent in scaled-charge FFs leads to an underestimation of the solute-solvent electrostatic interaction and thus also the enthalpy and free energy of solvation; this effect is particularly pronounced for polar solutes. In some cases, we find that this artificial reduction in the solute-solvent interaction can also alter the apparent phase behavior of the resulting solution. Overall, the totality of our results suggests that explicit polarization (rather than charge scaling) is likely necessary to provide high transferability to both neat IL and IL mixtures and solutions.

Solubility of Polar and Nonpolar Aromatic Molecules in Subcritical Water: The Role of the Dielectric Constant.

Liquid water at temperatures above the boiling point and high pressures, also known as pressurized hot water, or subcritical water (SBCW), is an effective solvent for both polar and nonpolar organic solutes. This is often associated with the decrease of water's dielectric constant at high temperatures, apparently allowing water to behave like an organic solvent. The decrease of the solubility at high pressures, in turn, is explained by a mild increase of the dielectric constant of water. Nevertheless, the relationship among the dielectric constant of water, hydration, and the solubilities of polar and nonpolar molecules in SBCW remains poorly understood. Here, we study, through molecular dynamics, the hydration thermodynamic parameters and the solubility of nonpolar and polar aromatic model systems, for which a solubility increase in SBCW is observed. We show that the temperature dependence of the hydration free energy of the model nonpolar aromatic solutes is nonmonotonic, exhibiting a solute size independent maximum at ∼475 K, above which hydration becomes entropically favorable and enthalpically unfavorable. The monotonic increase of the solubility, separated here in hydration and vaporization or sublimation components of the pure liquid or solid solute, respectively, is, in turn, related to the temperature increase of the latter, and only to a minor extent with the decrease of the hydration free energy above ∼475 K, via the hydration entropy. A solubility increase or decrease is also found at high pressures for different solutes, explained by the relative magnitude of the hydration and the vaporization or sublimation components of the solubility. For the model solid polar system studied, the hydration free energy increases monotonically with the temperature, instead, and the solubility increase is caused by the decrease of the sublimation component of the solubility. Thus, despite the observed increase of the hydration free energy with pressure, related to the entropic component decrease, our results indicate that the dielectric constant plays no significant role on the solubility increase of nonpolar and polar solutes in SBCW, opposite to the dielectric constant picture. The structure of water next to the solutes is also investigated, and a structural enhancement at room temperature is observed, resulting in significantly stronger pair interactions between a water molecule and its third and fourth nearest water neighbors. This structural and energetic enhancement nearly vanishes, however, at high temperatures, contributing to a positive hydration entropy.

Removal of Cr(VI) from aqueous solutions using polymer nanotubes

The self-assembled polymer nanotubes were obtained by a simple solvothermal method. Its physicochemical properties were characterized by SEM, BET, TGA, FT-IR, XPS, and solid-state 13C magnetic resonance. The effects of initial pH, dosage, and coexisting ions were evaluated for its Cr(VI) adsorption performances. The result showed that polymer nanotubes surface had a large number of organic functional groups and porous structures. In 140 mg/L Cr(VI) solution, polymer nanotubes obtained the largest Cr(VI) adsorption capacity of 147.81 mg/g. Adsorption kinetics and isotherms agreed well with the pseudo-second-order and Redlich–Peterson models, respectively. The desorption process showed that the polymer nanotubes were easy to regenerate in strong polarity solution and had a high removal efficiency. Ionic strength played an important role in the adsorption and the adsorption interaction contained electrostatic interaction, reduction, and chelation in this work. The self-assembly method will constitute a highly efficient adsorbent.

Vibrational spectra, normal coordinate analysis, and structure of keto form of acetylacetone. A DFT approach

In this paper, we discuss the stability, structure, and vibrational assignment of possible keto forms (Ket1 and Ket2) of acetylacetone, AA, in the gas phase and solutions. The geometry optimization and harmonic and anharmonic vibrational frequencies are calculated at the B3LYP/6-311++G** level. In addition, we also optimize the molecular structure at the MP2/6-311++G(p,d) level. The investigation in solutions is carried out by means of the PCM-SCRF method. We study the relative stability of Ket1 and Ket2 in different media using B2PLYP/6-31+G(d,p) and CBS-QB3 levels. By comparing the IR spectra of AA in a polar solvent, CH3CN, and a nonpolar solvent, CCl4, and considering the theoretical results, the vibrational band frequencies of both keto and enol tautomers are distinguished. Our calculations and vibrational spectra confirm the coexisting of two keto forms in the solutions, designated as Ket1 and Ket2. According to both theoretical and experimental results, Ket1 and Ket2 are predominant in the nonpolar and polar solutions, respectively. In addition, we also do a normal coordinate analysis by using the normal mode eigenvectors obtained at the B3LYP/6-311++ G(d,p) level. The observed vibrational wavenumbers, IR and Raman relative intensities, and Raman depolarization ratios of AA and its deuterated analogous agree satisfactorily with the calculated results obtained at the B3LYP/6-311++G(d,p) method.

Modelling retention and peak shape of small polar solutes analysed by nano-HPLC using methacrylate-based monolithic columns

The development of methacrylate-based monolithic columns was studied for the separation of pharmaceutical hydrophilic compounds in nano-liquid chromatography. The selected polymerisation mixture consisted of 7.5% hexyl methacrylate, 4.5% methacrylic acid and 18.0% ethylene dimethacrylate (w/w), in a binary porogenic solvent (35:35 w/w 1-propanol/1,4-butanediol). The polymer synthesised with this mixture has a good permeability, not excessive back-pressure, and reasonable retention times for polar and non-polar solutes. Monolithic columns (12 cm total capillary length, 100 μm i.d.), prepared with this mixture, were able to produce hydrogen bonding and electrostatic interactions, giving rise to promising separations. To evaluate the chromatographic system, alkylbenzenes (neutral and hydrophobic compounds) and sulphonamides (hydrophilic drugs) were assayed. To optimise the chromatographic mobile phase in isocratic elution and characterise the retention mechanism for a mixture of eight sulphonamides, the performance of several mathematic models was checked in the description of retention. The behaviour of the monolithic capillary column was compared, in terms of selectivity and peak shape, to that obtained with a C18 column (9 cm × 4.6 mm i.d., 5 μm particle size) using a conventional HPLC equipment. The results revealed substantial differences in the interactions established for sulphonamides between the monolithic and C18 columns.

An efficient approach for the synthesis of magnetic separable Fe3O4@TiO2 core-shell nanocomposites and its magnetic and photocatalytic performances

A convenient and efficient approach for the synthesis of Fe3O4@TiO2 nanocomposites with core-shell structure has been demonstrated. It takes four steps for synthesis process. Oleic acid-coated monodisperse Fe3O4 nanoparticles are obtained firstly, and surface modified Fe3O4 nanoparticles are followed to proceed. Then Fe3O4@TiO2 core-shell nanocomposites are subsequently synthesized using tetrabutyl titanate (TBOT) as titanium source and some polar aprotic solvents used as the mixed solvents. The obtained core-shell structure is composed of a central Fe3O4 nanoparticle core with sequential TiO2 surface, whereas the outer TiO2 coating was useful for the degradation of organic contaminants. Different core-shell nanocomposites in different polar solution are obtained. Shell thickness of Fe3O4@TiO2 nanocomposites could be adjusted rationally by changing synthetic conditions. The measurements of the magnetic properties demonstrate that the Fe3O4@TiO2 core-shell nanocomposites exhibit magnetic behavior at room temperature. The degradation of methylene blue solution was also explored.

Selecting ultrafiltration membranes for fractionation of high added value compounds from grape pomace extracts

The purpose of the current study is to investigate the use of ultrafiltration membrane for the fractionation of phenolic compounds from subcritical water grape pomace extract and the separation of these compounds from other co-extracted components. The extract was assayed in a cross-flow apparatus against eleven membranes with molecular weight ranging from 100 to 2 kDa. Monitoring of the process was executed by determining performance parameters and retention coefficients of proteins, polysaccharides, sugars, phenolic and anthocyanin classes. Results indicated that retention of solutes was affected, not by size exclusion, but primarily by severe fouling phenomena due to polar solutes adsorption on the membrane surface. With the exception of the separation obtained between polymeric and monomeric proanthocyanidins, polysulfone membranes were not able to fractionate phenolic classes. Membranes starting of 20 kDa and over retained high percentages (>60%) of polysaccharides and proteins.

Activity coefficients at infinite dilution for various organic solutes in the ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate

Activity coefficients at infinite dilution (γi∞) for a variety of polar and non-polar organic solutes (alkanes, cycloalkanes, alkenes, alkyl benzenes, alcohols, 1,4-dioxane, acetone, acetonitrile, tetrahydrofuran, chloroform and dichloromethane) in the ionic liquid (IL) 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate ([C2OHmim][PF6]) have been determined by gas-liquid chromatography using the IL as the stationary phase. The measurements were conducted over the temperature range of 303–353 K. The partial molar excess Gibbs energies (ΔGiE,∞), enthalpies (ΔHiE,∞) and entropies (ΔSiE,∞) at infinite dilution of the 29 solutes in the IL have been calculated from the experimental γi∞ values obtained over the temperature range. The selectivity sij∞ and capacity kj∞ at T = 323.15 K for aliphatic/aromatic hydrocarbons and aliphatic/alcohol separation problems were calculated from the γi∞ and compared to the reported literature data for other [C2OHmim] based ILs.

Synthesis and characterization of new diacid monomers and poly (ester-imide) s: a study of thermal property relationship and solubility

Two dicarboxylic acids [2,2'-(((4-hydroxyphenyl) methylene) bis (3-Bromo-4,1- phenylene)) bis (1,3 dioxoisoindoline 5 carboxylic acid)) and 2,2 '(((2,4dichlorophenyl) methylene) bis (4,1-phenylene)) bis (1,3-dioxoisoindoline-5-carboxylic acid)] were made by the reaction of pyromellitic anhydride (PMDA) with diamine in a solvent of g pyridine/glacial acetic acid at refluxing temperature. The organization of the diacid monomers is defined by FTIR and 1H-NMR spectroscopy. The sequence of new poly (ester-imide) s are arranged of two di acids and aromatic diols: [Bis (4hydroxyphenyl) 2 furelmethaneand 4,4'((1,4phenylene (methanylyidene)) bis (azanylylidene)) diphenol] by employing the polycondensation in the company of the dibutyltine dilaurate as a catalyst. The PEIs were defined by FTIR, 1HNMR, and TGA. Poly (ester-imide) s showed excellent solubility in polar aprotic solutions because of the existence of flexible groups in the polymer backbone. Furthermore, they displayed better thermal constancy, and the heat at that 10% loss of weight happened about700 to 800°C.

Comparison of the free-standing flexible electrodes fabricated with metallic 1T or semiconducting 2H MoS2 nanosheets and high conductivity PEDOT:PSS

The improvement and promotion of the active materials in supercapacitors (SCs) have been gotten a lot of attention with the emergency awareness of environment protection and energy crisis. Herein, a free-standing flexible film was developed as the active electrodes of SCs, fabricated by mixing 1T or 2H MoS2 nanosheets with high electric conductivity poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) via vacuum filtration and H2SO4 post-treatment. The 2H MoS2–based hybrid electrodes with post-treatment and 10% mass ratio for 2H MoS2 to PEDOT:PSS exhibited highest specific capacitance of 89Fg−1 @ 0.1 A g−1. Through the comparison between 1T MoS2 and 2H MoS2-based hybrid electrodes, 2H MoS2–based hybrid electrodes presented higher capacitance properties than 1T MoS2–based hybrid electrodes at the mass ratio range of 5% to 20%, while the capacitance performance of 1T MoS2–based hybrid electrodes was higher at range of 30% to 40%. It was assumed that the conductivity and capacitance performance of hybrid films were enhanced with organic polar solution (N,N-dimethylformamide) and H2SO4 post-treatment under the mass ratio range of 5% to 20%. Also, the high intrinsic capacitance of 2H MoS2 nanosheets was not achieved due to the poor electric conductivity for the mass ratio range of 30% to 40%. Therefore, it was an effective strategy to fabricate free-standing flexible hybrid electrodes with stable 2H MoS2 nanosheets and high conductivity materials for flexible energy storage and conversion.

Chemically Selective Transport in a Cross-Linked HII Phase Lyotropic Liquid Crystal Membrane.

The uniform size and complex chemical topology of the pores formed by self-assembled amphiphilic molecules such as liquid crystals make them promising candidates for selective separations. In this work, we observe the transport of water, sodium ions, and 20 small polar solutes within the pores of a lyotropic liquid crystal (LLC) membrane using atomistic molecular simulations. We find that the transport of a species is dependent not only on molecular size but also on chemical functionality. The membrane's inhomogeneous composition gives rise to radially dependent transport mechanisms with respect to the pore centers. We observe that all solutes perform intermittent hops between lengthy periods of entrapment. Three different trapping mechanisms are responsible for this behavior. First, solutes that drift out of the pore can become entangled among the dense monomer tails. Second, solutes can donate hydrogen bonds to the monomer head groups. Third, solutes can coordinate with sodium counterions. The degree to which a solute is affected by each mechanism is dependent on the chemical functionality of the solute. Using the insights developed in this study, we can begin to think about how to redesign existing LLC membranes to perform solute-specific separations.

Microwave Heating Outperforms Conventional Heating for a Thermal Reaction that Produces a Thermally Labile Product: Observations Consistent with Selective Microwave Heating.

Microwave (MW) heating is more effective than conventional (CONV) heating for promoting a high-temperature oxidative cycloisomerization reaction that was previously reported as a key step in a total synthesis of the natural product illudinine. The thermal reaction pathway as envisioned is an inverse electron-demand dehydro-Diels-Alder reaction with in situ oxidation to generate a substituted isoquinoline, which itself is unstable to the reaction conditions. Observed reaction yields were higher at a measured bulk temperature of 200 °C than at 180 °C or 220 °C; at 24 hours than at earlier or later time points; and when the reaction solution was heated using MW energy as opposed to CONV heating with a metal heat block. Selective MW heating of polar solute aggregates is postulated to explain these observations.

Protocol to compare column performance applied to hydrophilic interaction liquid chromatography

The lack of retention of highly polar solutes in liquid chromatography with reversed phase columns (RPLC) can be solved through the use of the hydrophilic interaction liquid chromatographic (HILIC) mode. Due to the complexity of the separation mechanisms in HILIC and the different factors that may have significant influence, the selection of the appropriate stationary phase plays a fundamental role in the development of analytical procedures to obtain good performance. In this work, the chromatographic performance of bare silica and six polar stationary phases with different functionalized groups (with neutral, cationic, anionic and zwitterionic character) are investigated. The behaviour is compared in terms of retention, selectivity, peak shape, and resolution, using acetonitrile-water mobile phases buffered at pH 3 and some correlation tools previously developed for RPLC. Six nucleosides and uracil were used as probe compounds. The results revealed significant differences among the columns regarding all inspected parameters. Some insight on the interactions established between solutes, and both stationary and mobile phases, is also given.