Acetonitrile Research Articles

The TOPGöt high-mass star-forming sample

Aims. The TOPGöt project studies a sample of 86 high-mass star-forming regions in different evolutionary stages from starless cores to ultra compact HII regions. The aim of the survey is to analyze different molecular species in a statistically significant sample to study the chemical evolution in high-mass star-forming regions, and identify chemical tracers of the different phases. Methods. The sources have been observed with the IRAM 30 m telescope in different spectral windows at 1, 2, and 3 mm. In this first paper, we present the sample and analyze the spectral energy distributions (SEDs) of the TOPGöt sources to derive physical parameters such as the dust temperature, Tdust, the total column density, NH2, the mass, M, the luminosity, L, and the luminosity-to-mass ratio, L∕M, which is an indicator of the evolutionary stage of the sources. We use the MADCUBA software to analyze the emission of methyl cyanide (CH3CN), a well-known tracer of high-mass star formation. Results. We built the spectral energy distributions for ~80% of the sample and derived Tdust and NH2 values which range between 9−36 K and ~3 × 1021−7 × 1023 cm−2, respectively. The luminosity of the sources spans over four orders of magnitude from 30 to 3 × 105 L⊙, masses vary between ~30 and 8 × 103 M⊙, and the luminosity-to-mass ratio L∕M covers three orders of magnitude from 6 × 10−2 to 3 × 102 L⊙∕M⊙. The emission of the CH3CN(5K-4K) K-transitions has been detected toward 73 sources (85% of the sample), with 12 nondetections and one source not observed in the frequency range of CH3CN(5K-4K). The emission of CH3CN has been detected toward all evolutionary stages, with the mean abundances showing a clear increase of an order of magnitude from high-mass starless cores to later evolutionary stages. We found a conservative abundance upper limit for high-mass starless cores of XCH3CN < 4.0 × 10−11, and a range in abundance of 4.0 × 10−11 < XCH3CN < 7.0 × 10−11 for those sources that are likely high-mass starless cores or very early high-mass protostellar objects. In fact, in this range of abundance we have identified five sources previously not classified as being in a very early evolutionary stage. The abundance of CH3CN can thus be used to identify high-mass star-forming regions in early phases of star-formation.

Ligand and solvent effects on the kinetics of the electrochemical reduction of Ni(II) complexes: Experiment and quantum chemical modeling

The two-electron reduction of some Ni(II) complexes with α-diimine ligands ([Ni(bpy)3]2+ and [Ni(pybox)2]2+) at a platinum electrode from acetonitrile (AN) and dimethylformamide (DMF) solutions is investigated by cyclic voltammetry (CV). Digisim simulations are employed to determine kinetic parameters. For [Ni(bpy)3]2+ in AN the first electron transfer (ET) step was found to be rate-controlling. The rate constants of the first and second steps (k1 and k2) are practically the same in the DMF solution. In contrast, the second ET step is rate controlling for the [Ni(pybox)2]2+ complex in AN, while the difference between k1 and k2 for this complex reactant in DMF becomes less noticeable. Molecular modeling based on the quantum mechanical theory of electron transfer and on density functional theory (DFT) calculations is performed for the first time to predict the activation barriers of the two-step heterogeneous redox processes and to elucidate the role of the ligands and solvents in the kinetics of these processes. Three-dimensional reaction free energy surfaces are constructed along the solvent and intramolecular coordinates. The electronic transmission coefficients are estimated as well. The results of model calculations are in qualitative agreement with the experimental data.

Significant Enhancement of Thermoelectric Properties of PTB7 Conducting Polymer by Mixed-Solvent Approach.

The thermoelectric properties of poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}), commonly known as PTB7 conducting polymer, were investigated for the first time by Rastegaralam et al. in 2017 [ Crystals 2017, 7, 292]. PTB7 showed higher electrical conductivity or Seebeck coefficient (or even both) and, hence, a higher thermoelectric power factor than a variety of organic semiconductors. Therefore, it is worth working more on this semiconductor to improve its thermoelectric figure of merit. In this work, for the first time the effect of cosolvents on the thermoelectric properties of PTB7 is investigated. PTB7 conducting polymer dissolved in chlorobenzene was treated with different solvents: N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), acetonitrile (AC), and 1,2-dichloroethane (DCE). Upon addition of DMF, DMSO, and NMP, a significant enhancement in the electrical conductivity of the samples accompanied by a reduction in the Seebeck coefficient occurred as a result of doping, while the use of AC and DCE led to simultaneous enhancement in the electrical conductivity and the Seebeck coefficient by increasing the mobility. The dopants used in this work are inexpensive, are easily available, and do not need to perform any synthesis process. The highest estimated figure of merit value obtained in this work without optimization is 0.1, which is of the highest values for organic thermoelectric materials.

Molecular Structural Evolution of Near-Infrared Cationic Aggregation-Induced Emission Luminogens: Preclinical Antimicrobial Pathogens Activities and Tissues Regeneration

Molecular Structural Evolution of Near-Infrared Cationic Aggregation-Induced Emission Luminogens: Preclinical Antimicrobial Pathogens Activities and Tissues Regeneration

Solvatochromism of a D205 indoline dye at the interface of a small TiO2-anatase nanoparticle in acetonitrile: a combined molecular dynamics simulation and DFT calculation study

ABSTRACT A combined molecular dynamics (MD) simulation and density functional theory (DFT) calculations were used to investigate the effect of the acetonitrile (ACN) solution on the absorption and the charge transfer in a D205 indoline dye at the interface of a TiO2 nanoparticle. DFT calculations were carried out to estimate the equilibrium geometry of a small Ti30O62H4-anatase nanoparticle and to derive interaction parameters for bidentate binding of a D205 dye to TiO2. A series of the D205 dye configurations anchored to Ti30O62H4 were generated from the MD simulations and used as input for the time-dependent DFT (TD-DFT) calculations. We found that the immersion of the D205-Ti30O62H4 composite system into the polar ACN environment results in conformational changes of the dye moiety, which are accompanied by the solvatochromic redshift of its long-wavelength absorption band up to 1900 cm-1. Our results show that the HOMO and LUMO energy level alignment of the dye and the nanoparticle suggests a favourable driving force for charge transfer from the dye to TiO2. The MD/TD-DFT-estimated solvatochromic shift for the D205 dye at the TiO2/ACN interface is in good agreement with the experiment, showing that such computational approach enables reliable predictions of optical properties of other dye-TiO2 composites in solution.

Centrifugally spun poly(ethylene oxide) fibers rival the properties of electrospun fibers

AbstractCentrifugal force spinning (CFS), also known as centrifugal spinning, forcespinning, or rotary jet spinning, provides considerably higher production rates than electrospinning (ES), but the more widespread use of CFS as an alternative depends on the ability to produce fibers with robust thermal and mechanical properties. Here, we report the CFS of poly(ethylene oxide) (PEO) fibers made using a spinning dope formulated with acetonitrile (AcN) as the volatile solvent, and we describe the thermal and mechanical properties of the centrifugally‐spun fibers. Even though the formation, diameter, and morphology of electrospun and centrifugally‐spun PEO fibers are relatively well‐studied, the article presents three crucial contributions: the pioneering use of PEO solutions in AcN as spinning dope, characterization of crystallinity and mechanical properties of the centrifugally‐spun PEO fibers, and a comparison with the corresponding properties of electrospun fibers. We find that fiber formation occurrs for the chosen CFS conditions if polymer concentration exceeds the entanglement concentration, determined from the measured specific viscosity. Most significantly, the centrifugally spun PEO fibers display crystallinity, modulus, elongation‐at‐break, and fiber diameter that rival the properties of electrospun PEO fibers reported in the literature.

Determination and correlation of solubility of an explosive in different pure solvents

Information regarding relevant solid–liquid balance pertaining to 3-nitro-1H-pyrazole (3-NP) within a range of solvents is of a high significance to the preliminary analysis of industry-related uses. Here, through the gravimetric approach, 3-NP dissolvability in various clean solvents, i.e., n-butyl acetate (NBAC), isopropyl acetate (IPAC), n-propyl acetate (NPAC), ethyl acetate (EAC), methyl acetate (MAC), n-propanol (Pro-OH), ethanol (EtOH), methanol (MeOH), toluene (PhMe), acetonitrile (AN), tetrahydrofuran (THF), acetone (DMK), water and benzene (Ph), was explored under an atmosphere pressure of 0.1 MPa and within a range of temperature (T = 283.15 K to 323.15 K). In accordance with the outcomes, with the rise of the temperature, 3-NP dissolvability increased in fourteen solvents taken. Among all the solvents, water exhibiting the maximum polarity had the minimum dissolvability, while methanol exhibited the maximum quality of solubility. At a particular temperature, 3-NP’s quality of solubility followed that of MeOH (8.54 × 10-2, 323.15 K) > EtOH (6.46 × 10-2, 323.15 K) > Pro-OH (6.27 × 10-2, 323.15 K) > AN (4.18 × 10-2, 323.15 K) > DMK (3.76 × 10-2, 323.15 K) > MAC (3.20 × 10-2, 323.15 K) > EAC (2.82 × 10-2, 323.15 K) > NPAC (2.25 × 10-2, 323.15 K) > NBAC (1.91 × 10-2, 323.15 K) > IPAC (1.25 × 10-2, 323.15 K) > THF (1.07 × 10-2, 323.15 K) > PhMe (7.29 × 10-3, 323.15 K) > Ph (3.23 × 10-3, 323.15 K) > water (2.16 × 10-3, 323.15 K). The experimental data of 3-NP had a correlation according to Wilson approach, NRTL model, λh equation and the modified Apelblat equation. As was revealed from the fitting outcomes, the optimal correlative result of the experimental information was given through NRTL model. The relative average deviation (102ARD) and the root-mean-square deviation (104RMSD) achieved were lower than 9.44 and 23.75 separately. Moreover, 3-NP dissolvability characteristics in solvents studied were analyzed with the use of the Hansen dissolvability coefficient (δd, δp, δh, δt, and Δδt) here. This study determined the effect exerted by interacting processes pertaining to solvent–solute and solvent–solvent molecules upon the 3-NP’s quality of solubility with the association of linear solving energy in accordance with the descriptors of the solvents. Moreover, the mixing characteristics of 3-NP in 14 pure solvents, including the mixing Gibbs energy (ΔmixG), mixing enthalpy (ΔmixH) and mixing entropy (ΔmixS), were determined and analyzed through Wilson approach. The result of ΔmixG < 0 indicated that the dissolution pertaining to 3-NP in the solvents taken was spontaneous. The data pertaining to lnγ1∞ and lnγ1 was similar, demonstrating that 3-NP in the solution mechanisms of solvents taken was not highly non-ideal. The results presented conducive data in terms of actual 3-NP crystallization optimizing procedure.

Moderately Concentrated Acetonitrile‐containing Electrolytes with High Ionic Conductivity for Durability‐oriented Lithium‐Ion Batteries

AbstractElectrode protection additives for acetonitrile (AN)‐containing electrolytes play an important role for the usability of such electrolytes since it is decomposed reductively and electrochemically on the negative electrode of lithium‐ion batteries. The durability of electrolytes containing AN with low concentration of lithium salt was investigated by electrochemical measurements to achieve the desired battery performance derived from high ionic conductivity. The reductive decomposition of AN was suppressed by adding vinylene carbonate and ethylene sulfite as solid electrolyte interface formation additives. The high temperature durability performance with various positive electrode chemistries was improved by applying pyridine as a stabilizer for LiPF6. The AN‐containing electrolyte enhances low temperature performance and long‐term performance at high temperatures due to higher molecular mobility and a low electrode interface barrier. This electrolyte not only increases the capacity by enabling the usage of thicker electrodes, but also reduces the total cost of battery production.

Tracking the Micro-Heterogeneity and Hydrogen-Bonding Interactions in Hydroxyl-Functionalized Ionic Liquid Solutions: A Combined Experimental and Computational Study.

Ionic liquids (ILs) are an important class of media that are usually used in combination with polar solvents to reduce costs and tune their physicochemical properties. In this regard, it is essential to understand the influence of adding solvents on the properties of ILs. In this work, the micro-heterogeneity and H-bonding interactions between a hydroxyl-functionalized IL, [HOEmim][TFSI], and acetonitrile (ACN) were investigated by attenuated total reflection Fourier transform infrared spectroscopy and molecular simulations. All studied IL-ACN mixtures were found to deviate from the ideal mixtures. The degree of deviations reaches the maximum at about x(ACN)=0.7 with the presence of both homogeneous clusters of pure IL/ACN and heterogeneous clusters of IL-ACN. With the addition of ACN to IL, the mixtures undergo the transformation from "ACN solvated in [HOEmim][TFSI]" to "[HOEmim][TFSI] solvated in ACN". It is found that the newly formed H-bonding interactions between the IL and ACN is the main factor that contributes to the red shifts of O-H, C2 -H, C4,5 -H, and Calkyl -H of [HOEmim]+ cation, and the blue shifts of C-D, C≡N of ACN, and C-F, S=O of [TFSI]- anion. These in-depth studies on the mixtures of hydroxyl-functionalized IL and acetonitrile would help to understand the micro-heterogeneity and H-bonding interactions of miscible solutions and shed light on exploring their applications.

Investigation of the aggregation, clouding and thermodynamics of the mixture of sodium alginate with sodium dodecyl sulfate and triton X-100 in aqueous and aqua-organic mixed solvents media

Herein, the aggregation, phase separation and binding behavior of sodium alginate (SA) and surfactants (anionic (SDS) and nonionic (TX-100)) mixture in aqueous and aqua-organic mixed solvents have been investigated applying the conductivity, cloud point, and UV–visible spectroscopic methods. In the current study, the various physico-chemical parameters (critical micelle concentration (CMC), extent of bound counter ions, cloud point (CP), binding constant (Kb), thermodynamic properties, and transfer parameters) were determined. The addition of SA facilitates SDS micellization. The CMC of the SA + SDS mixtures were obtained to be dependent on SA concentration, composition of mixed solvents, and temperature. The CMC of the SA + SDS mixture were found to be greater in magnitude in aqua-organic (dimethyl formamide (DMF), acetonitrile (AN), ethylene glycol (EG), and 1,4-dioxane (DX)) mixed solvents than the values observed in H2O medium. The values of counterion binding were found to be enhanced with the boost of concentration of SA and other organic additives. The Kb values of SA + TX-100 mixtures were computed from the Benesi-Hildebrand (BH) plot and the Kb values were found to be temperature-dependent. The CP values of the SA + TX-100 mixture experienced a lessening with growing contents of SA and got enhanced in diols (EG/ propanediol (PrD)) media. The negative values of free energy changes dictate that the micellization of SA + SDS mixture and binding processes for the SA + TX-100 mixture are spontaneous in nature while the positive free energy changes indicate the non-spontaneity of clouding phenomena of SA + TX-100 mixture. The obtained values of enthalpy and entropy changes recommend the presence of hydrophobic, electrostatic, and ion–dipole interactions amongst SA and SDS while hydrogen bonding, ion–dipole, and van der Walls forces are the proposed forces between SA and TX-100. Excellent enthalpy–entropy compensation was observed in each case.

Extension of the potential intervals of high redox activity and electronic conductivity of polypyrrole films on electrode surface via their electrochemical multi-cycle treatment in monomer-free solution

Thin polypyrrole films (thickness: about 30 nm) have been deposited at electrode surface via potentiostatic oxidation of dilute (1 mM) pyrrole solution in acetonitrile (AN). It has been shown that their subsequent treatment by means of multi-cycle voltammetry within a broad potential range (up to -2.0 V vs. Ag/Ag+ in AN) leads to their "activation", i.e. to a very strong extension of their redox response region in the negative direction as well as to almost uniform distribution of the redox activity within this potential range. Region of their high conductivity under in situ conditions has also extended significantly. Spectral and electrocatalytic properties of such PPy films before and after their "activation" have been analyzed. Two parameters for characterization of the variation of film's properties in the course of its "activation" (redox efficiency of polymerization and width of electroactivity region) have been proposed. Comparison of films deposited at different potentials (from 0.6 V to 0.8 V) has revealed that the effect of their "activation" increases for lower polymerization potential. Films deposited at 0.6 V possess after their "activation" a very broad electroactivity range (almost 2.5 V) and a record high redox charge per monomer unit (its oxidation degree) inside the film in contact with AN solution, 0.45. Such unusual properties of "activated" PPy films make them prospective materials for various applications.

Solvent influence on manufacturability, phase behavior and morphology of amorphous solid dispersions prepared via bead coating

Bead coating or fluid-bed coating serves as an auspicious solvent-based amorphous solid dispersion (ASD) manufacturing technique in respect of minimization of potential physical stability issues. However, the impact of solvent selection on the bead coating process and its resulting pellet formulation is, to the best of our knowledge, never investigated before. This study therefore aims to investigate the influence of the solvent on the bead coating process itself (i.e. manufacturability) and on solid-state characteristics of the resulting ASDs coated onto beads. For this purpose, the drug-polymer system felodipine (FEL)-poly(vinylpyrrolidone-co-vinyl acetate) (PVP-VA) was coated onto microcrystalline cellulose (MCC) beads from acetonitrile (ACN), methanol (MeOH), ethanol (EtOH), acetone (Ac), 2-propanol (PrOH), dichloromethane (DCM) and ethyl acetate (EthAc). A drug loading screening approach with bead coating revealed analogous ability to manufacture high drug-loaded ASDs from the different organic solvents. The results show no correlation with crystallization tendency or with equilibrium solubility of the drug in the different solvents, nor with the solvent-dependent drug-polymer miscibility obtained from film casting experiments. Distinct coating morphologies were however observed for PVP-VA and FEL-PVP-VA ASDs deposited onto beads from the various solvents, which is attributed to differences in solvent evaporation kinetics.

Maternal Rat Metabolomics: Amniotic Fluid and Placental Metabolic Profiling Workflows.

Studying the metabolome of specific gestational compartments is of growing interest in the context of fetus developmental disorders. However, the metabolomes of the placenta and amniotic fluid (AF) are poorly characterized. Therefore, we present the validation of a fingerprinting methodology. Using pregnant rats, we performed exhaustive and robust extractions of metabolites in the AF and lipids and more polar metabolites in the placenta. For the AF, we compared the extraction capabilities of methanol (MeOH), acetonitrile (ACN), and a mixture of both. For the placenta, we compared (i) the extraction capabilities of dichloromethane, methyl t-butyl ether (MTBE), and butanol, along with (ii) the impact of lyophilization of the placental tissue. Analyses were performed on a C18 and hydrophilic interaction liquid chromatography combined with high-resolution mass spectrometry. The efficiency and the robustness of the extractions were compared based on the number of the features or metabolites (for untargeted or targeted approach, respectively), their mean total intensity, and their coefficient of variation (% CV). The extraction capabilities of MeOH and ACN on the AF metabolome were equivalent. Lyophilization also had no significant impact and usefulness on the placental tissue metabolome profiling. Considering the placental lipidome, MTBE extraction was more informative because it allowed extraction of a slightly higher number of lipids, in higher concentration. This proof-of-concept study assessing the metabolomics and lipidomics of the AF and the placenta revealed changes in both metabolisms, at two different stages of rat gestation, and allowed a detailed prenatal metabolic fingerprinting.

Lactic Acid-Based Solvents for Sustainable EDLC Electrolytes

The most relevant electrolytes used in commercial electrical double layer capacitors (EDLCs) are based on non-aqueous solvents as acetonitrile (ACN) and propylene carbonate (PC). However, these solvents are synthesized from non-renewable fossil feedstocks, making it desirable to develop more sustainable alternatives. To address this issue, in this work lactic acid was used to synthesize a panel of substances with small structural variation. The investigated products belong to the chemical family of ketals, and among them the 5-methyl-1,3-dioxolan-4-one (LA-H,H) was found to be the most suitable to prepare electrolytic solutions. Therefore, LA-H,H was combined with triethylmethylammonium tetrafluoroborate (TEMABF4), and analyzed in symmetrical EDLC. This electrolyte was thoroughly characterized by cyclic voltammetry, galvanostatic cycles and electrochemical impedance spectroscopy (EIS), disclosing competitive performances compared to PC-based electrolyte. The EDLC with LA-H,H/TEMABF4 displayed a specific energy and power of 13.4 Whkg−1 and 22.5 kWkg−1 respectively, with an optimal cycling stability over 5000 cycles at different current densities.

Synthesis of new azobenzo[c]cinnolines and investigation of electronic spectra and spectroelectrochemical behaviours

A series of disazobenzo[c]cinnoline dyes was prepared by coupling reaction of 3,8-dihydroxybenzo[c]cinnoline with diazotised aromatic amines. The structures of these dyes were confirmed using UV–Vis, FTIR, 1H NMR, LC-MS/MS and LC-MS/TOF spectroscopic techniques. 13C NMR, 13C-DEPT, 1H–1H COSY, 1H–13C HMQC and 1H–13C HMBC spectra of dye 12 were demonstrated in this study. In addition, the effects of the substituent attached to the phenyl ring, solvent and acid-base on the UV-Vis spectra of the dyes were investigated. Besides, voltammetric and spectroelectrochemical behaviours of four disazobenzo[c]cinnolines (2, 8, 11 and 13) in acetonitrile (ACN) solution were also evaluated. It was observed that the disazobenzo[c]cinnoline derivatives indicated reversible voltammetric behaviour in acetonitrile-tetrabutylammonium perchlorate (ACN-TBAP) solution. A square-wave potential step method coupled with optical spectroscopy was used to probe switching times and optic contrast of the dyes.

Solvent contribution to ferrocene conformation: Theory and experiment

Solvent impacts on ferrocene configuration and the nature of its component energies. The measured infrared (IR) spectra of ferrocene (Fc) in the region 400-500 cm−1 exhibit very different profiles in gas phase and in solutions. The present study further explores such the differences in gas phase and in solutions using combined theoretical calculations and experimental measurements. It concentrates on the IR spectra in the region of 400–1200 cm−1 using non-polar (tetrachloromethane (CCl4) and n-hexane (Hex)) and polar (acetonitrile (ACN), dichloromethane (DCM), tetrahydrofuran (THF) and 1,4-dioxane (DOX)) solvents. Six relatively intense normal modes in this region (ν7, ν8,9, ν18, ν22,23, ν30,31 and ν37 at approximately 482, 495, 815, 840, 1006, 1110 cm−1) were obtained. The dependence of the relative energies of the eclipsed and staggered rotamers of Fc on the polarity of the solvent is small. Analysis of the band profile for the vibrational modes in the 480-500 cm−1 region (ν7, ν8,9) using the reaction coordinate model suggests that the energy difference between the eclipsed and staggered rotamers (ΔEe-s solv) may be underestimated by implicit solvent model in the calculations. Further investigation in this direction is warranted. The impact of solvation on Fc configuration is further investigated using energy decomposition analysis (EDA) in a non-polar (tetrachloromethane (CCl4)) and a polar (acetonitrile (ACN)) solvent. These calculations suggest that solvation substantially changes the electrostatic and quantum mechanical Pauli energy contributions to the interaction energy of Fc conformers, which result in a large steric energy in solvents to enhance the dominance of the eclipsed Fc, an observation consistent with the analysis of the bands due to the ν7 and ν8,9 vibrational modes.

Antimicrobial and antioxidant activity of Evernia prunastri extracts and their isolates

Lichens are symbiotic organisms formed by a fungus and one or more photosynthetic partners which are usually alga or cyanobacterium. Their diverse and scarcely studied metabolites facilitate adaptability to extreme living conditions. We investigated Evernia prunastri (L.) Ach., a widely distributed lichen, for its antimicrobial and antioxidant potential. E. prunastri was sequentially extracted by hexane (Hex), dichloromethane (DCM) and acetonitrile (ACN) that were screened for their antioxidant and antimicrobial (against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans) activities. The Hex extract possessed the highest antioxidant capacity (87 mg ascorbic acid/g extract) corresponding to the highest content of phenols (73 mg gallic acid/g extract). The DCM and Hex extracts were both active against S. aureus (MICs of 4 and 21 µg/ml, respectively) but were less active against Gram-negative bacteria and yeast. The ACN extract exhibited activity on both S. aureus (MIC 14 µg/ml) and C. albicans (MIC 38 µg/ml) and was therefore further fractionated by silica gel column chromatography. The active compound of the most potent fraction was subsequently characterized by 1H and 13C-NMR spectroscopy and identified as evernic acid. Structural similarity analyses were performed between compounds from E. prunastri and known antibiotics from different classes. The structural similarity was not present. Antioxidant and antimicrobial activities of E. prunastri extracts originate from multiple chemical compounds; besides usnic acid, most notably evernic acid and derivatives thereof. Evernic acid and its derivatives represent possible candidates for a new class of antibiotics.Graphic abstract

Clinical Application Study of Polymeric Nanospheres Network in Methylphenidate Extraction from Urine Samples by Dispersive Solid Phase Extraction Adsorbent.

Purpose: This research introduces a polymeric nanosphere as a new dispersive solid phase extraction (DSPE) adsorbent for the extraction of methylphenidate (MPH) from urine and its high performance liquid chromatography (HPLC) analysis. Methods: Polymeric nanosphere is a kind of copolymeric network obtained by copolymerization of an ionic liquid monomer and styrene in the presence of vinyltriethoxysilane and 2-hydroxyethylmethacrylate. HPLC coupled with ultra violet detector was applied for the determination and quantification of MPH. Dominant parameters in extraction were modified by the one-parameter-at-a-time method. The results are as follow: 10 mg of polymeric nanospheres (PNS), 400 μL of acetonitrile (ACT), 5 mL of urine with the pH value of 9, and the extraction and desorption times of 2 and 5 minutes, respectively, which can be selected as the optimum extraction conditions. Results: Calibration curve was plotted through optimized conditions, and the proposed method was validated. The results demonstrated that the method presented linearity in the concentration range of 30-1200 ng/mL. Selectivity, matrix effect and metabolites interference effect were investigated and the method presented no obvious interference effect during the analysis run time. Repeatability, limit of detection (LOD) and limit of quantification (LOQ) values of the method can be reported in this section as well. The method showed satisfactory results with 98.8% relative recovery in the analysis of positive urine samples. Conclusion: The findings convinced the applicability of the introduced method for DSPE and HPLC analysis of the positive urine samples in different laboratories.

Determination of SK7324, a new class of hepatitis C virus inhibitor, in rat plasma by UPLC-MS/MS and its application to the pharmacokinetic study of SK7324.

In this study, a sensitive method for quantitation of the unique small-molecule inhibitor of hepatitis C virus SK7324 in rat plasma has been established using ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). SK7324 and internal standard (tramadol) in plasma sample was extracted using acetonitrile. A centrifuged upper layer was then evaporated and reconstituted with the mobile phase of 0.5% formic acid-acetonitrile (35:65, v/v). The reconstituted samples were injected into a C18 reversed-phase column. Using MS/MS in the multiple reaction monitoring (MRM) mode, SK7324 and tramadol were detected without severe interference from rat plasma matrix. Detection of SK7324 in rat plasma by the UPLC-ESI/MS/MS method was accurate and precise with a quantitation limit of 1.0 ng/mL. The validation, reproducibility, stability, and recovery of the method were evaluated. The method has been successfully applied to pharmacokinetic studies of SK7324 in rat plasma. Pharmacokinetic parameters of SK7324 were evaluated after intravenous (i.v.; at doses of 5 mg/kg) and oral (p.o.; at doses of 10 mg/kg) administration of SK7324 in rats. After p.o. administration (10 mg/kg) of SK7324, F (Fraction absorbed) value was approximately 87.1%.

Back Cover: Separation of pharmaceutically active compounds by multimodal chromatography with ultraviolet detection

The cover picture shows the retention behavior of positively charged thiamine and basic cytosine in mobile phases with three different buffer types at low and high acetonitrile (ACN) content on three different mixed-mode columns. All three columns contain the same C18 hydrophobic moiety and differ only in the hydrophilic parts (HILIC-1, WAX-1 and WCX-1). The effect of the buffer type on the retention is significantly affected by ACN content as well as the chemical structure of the analytes and columns. While differences in cytosine retention at low and high ACN content are comparable for all buffers tested, unexpectedly long retention is observed for thiamine at high ACN content, especially in combination with phosphate buffer.