Liquid–solid disk extraction followed by supercritical fluid elution and gas chromatography of phenols from water

A method combining the techniques of liquid – solid disk extraction (LSDE) and supercritical fluid elution (SFE) has been developed for the phenols regulated by the Clean Water Act. LSDE uses a disk or membrane made of polytetrafluoroethylene (PTFE) fibrils impregnated with small particles, e.g. styrene divinylbenzene (SDB) resin, to extract phenols from water. After disk extraction the retained analytes are eluted from the disk using SFE. SFE is used as an alternative to liquid solvent elution with an organic solvent. Analytes are separated, identified, and quantified using gas chromatography – ion trap detector mass spectrometry (GC-ITDMS). The method is capable of sub parts per billion detection limits, and precision of 5–28% RSD. Evaluation of various disks or membranes, such as C₁₈-silica disks, SDB disks, and ion exchange membranes, has also been performed for the extraction of phenols from water. The results obtained from the in-situ aqueous acetylation of phenols and extraction of their acetates are quantitative. The utilization of LSDE and SFE techniques has proven to be a more effective approach than liquid – liquid extraction in minimizing air pollution and solvent waste.     

A PMMA composite as an optical diffuser in a liquid crystal display backlighting unit (BLU)

The effect of thermo-physical properties, relative humidity and stiffness on the warpage of a poly(methyl methacrylate) (PMMA) diffusing plate modified with glass fibers in a direct-lit backlight unit (BLU) of a liquid crystal display (LCD) was investigated. The warpage of the PMMA diffusing composites modified with a glass fiber were significantly reduced relative to that of a conventional PMMA diffusing plate. Luminance and scattering characteristics of the PMMA diffusing composites having 5, 10, 20 vol% of glass fibers were measured. Although the luminance of the composite was lowered as increasing the volume fractions of glass fibers in the PMMA composites, good brightness uniformity of the composites on a light source was obtained.     

Depolymerization and ionic conductivity of enzymatically deproteinized natural rubber having epoxy group

Preparation of liquid epoxidized natural rubber (ENR) was made by oxidative depolymerization of ENR in latex stage without loss of epoxy group. Epoxidation of fresh natural rubber latex, which was purified by deproteinization with proteolytic enzyme and surfactant, was carried out with freshly prepared peracetic acid. The glass transition temperature (T_g) and gel content of the rubbers increased after the epoxidation, both of which were dependent upon an amount of peracetic acid. The gel content was significantly reduced by oxidative depolymerization of the rubber with (NH₄)₂S₂O₈ in the presence of propanal. The resulting liquid epoxidized rubber (M_n≈10⁴) was found to have well-defined terminal groups, i.e. aldehyde groups and α-β unsaturated carbonyl groups. The novel rubber was applied to transport Li⁺ as an ionic conducting medium, that is, solid polymer electrolyte.     

Dielectric,magnetic and mechanical properties of ferrite composites

The dielectric and magnetic properties of carbonyl—iron (CI) and nickel zinc ferrite polymer composites were studied with respect to the ferrite particulate content and microwave frequency. From the experimental data and using empirical models that relate the composite dielectric and magnetic properties, the respective dielectric and magnetic properties of the neat fillers were estimated. The tensile properties of the particulate composites comprising CI were shown to follow qualitatively Mooney's equation for the elastic modulus. The tensile strength of an elastomeric polyurethane and PVC composites containing CI increased with particulate content, while the elongation to break decreased with filler content. SEM micrographs of tensile fracture surfaces indicated that somewhat better adhesion is obtained in the case of the polyurethane-based composites compared to the PVC ones.     

Rapid analysis of triterpenic acids by liquid chromatography using porous graphitic carbon and evaporative light scattering detection

An original system which uses Porous Graphitic Carbon as support and a mixture of organic solvents as mobile phase is proposed for the analysis of triterpenic acids by liquid chromatography. The separation of betulinic acid, ursolic acid, oleanolic acid, and 18alpha- and 18beta-glycyrrhetinic acids was carried out within a short time and monitored by evaporative light scattering detection as universal detection method. Molecular modelling studies show that the main contribution to the selectivity comes from the electrostatic interaction characterised by the dipole moment of the products.     

Crystallization and second harmonic generation in thermally poled niobium borophosphate glasses

Crystallization of glasses with compositions (1−x)(0.95 NaPO₃+0.05 Na₂B₄O₇)+xNb₂O₅, x=0.4, 0.43, 0.45, 0.48 was investigated by differential scanning calorimetry and X-ray powder diffraction. Crystallization of two phases was observed in the glasses with x=0.43-0.48. First phase is a sodium niobate with the structure of tetragonal tungsten bronze () and second phase is Na₄Nb₈P₄O₃₂ (). The crystallization of sodium niobate is correlated with increasing of nonlinear optical efficiency reported for thermally poled glasses with x>0.4. The results of Raman spectroscopy show the formation of three-dimensional (3D) niobium oxide framework in the glasses with increase of niobium concentration. This framework is supposed to have tetragonal tungsten bronze structure and to be responsible for nonlinear optical properties of the glass. Second harmonic generation signals of as prepared and crystallized glass after thermal poling are compared. The nucleation and crystallization do not improve the NLO properties of the glasses under study.     

Drug metabolite cluster centers-based strategy for comprehensive profiling of Neomangiferin metabolites in vivo and in vitro and network pharmacology study on anti-inflammatory mechanism

Neomangiferin (NMF) is an extremely special xanthone that could be simultaneously attributed to C-glycoside and O-glycoside with a variety of biological activities, such as anti-inflammatory, antitumor, antipyretic, and so on. So far as we know, the metabolism profiling has been insufficient until now. Herein, Drug Metabolite Cluster Centers (DMCCs)-based Strategy has been developed to profile the NMF metabolites in vivo and in vitro. Firstly, the DMCCs was proposed depending on literature-related and preliminary analysis results. Secondly, the specific metabolic rule was implemented to screen the metabolites of candidate DMCCs from the acquired Ultra High Performance Liquid Chromatography Quadrupole Exactive Orbitrap Mass Spectrometry (UHPLC-Q-Exactive Orbitrap MS) data by extracted ion chromatography (EIC) method. Thirdly, candidate metabolites were accurately and tentatively identified according to the pyrolysis law of mass spectrometry, literature reports, comparison of reference substances, and especially the diagnostic product ions (DPIs) deduced preliminarily. Finally, network pharmacology was adopted to elucidate the anti-inflammatory action mechanism of NMF on the basis of DMCCs. As a result, 3 critical metabolites including NMF, Mangiferin (MF) and Norathyriol (NA) were proposed as DMCCs, and a total of 61 NMF metabolites (NMF included) were finally screened and characterized coupled with 3 different biological sample preparation methods including solid phase extraction (SPE), acetonitrile precipitation and methanol precipitation. Among them, 32 metabolites were discovered in rat urine, 30 in rat plasma, 12 in rat liver, 9 metabolites in liver microsomes and 8 in rat faeces, respectively. Our results also illustrated that NMF primarily underwent deglucosylation, glucuronidation, methylation, sulfation, dihydroxylation and their composite reactions in vivo and in vitro. Additionally, network pharmacology analysis based on DMCCs revealed 85 common targets of disease-metabolites, and the key targets were TNF, EGFR, ESR1, PTGS2, HIF1A, IL-2, PRKCA and PRKCB. They exerted anti-inflammatory effects mainly through the pathways of inflammatory response, calcium-dependent protein kinase C activity, nitrogen metabolism, pathways in cancer and so on. In general, our study constructed a novel strategy to comprehensive elucidate the biotransformation pathways of NMF in vivo and in vitro, and provided vital reference for further understanding its anti-inflammatory action mechanism. Moreover, the established strategy could be generalized to the metabolism and action mechanism study of other natural products.     

Chromatographic performance of deuterated solvents in reversed phase micro high performance liquid chromatography

The chromatographic performance of the deuterated solvents, CD₃OD and D₂O, has been investigated in reversed-phase micro high performance liquid chromatography. The chromatographic performance of CD₃OD is only slightly superior to that of CH₃OH. However, the performance of D₂ is significantly superior to that of H₂O, separation of aromatics being improved by about 30%. D₂ is a particularly powerful solvent for the separation iof deuterated and non-deuterated compounds.     

Analytical procedures for quantification of peptides in pharmaceutical research by liquid chromatography–mass spectrometry

Peptide quantification by liquid chromatography–mass spectrometry (LC–MS) combines the high resolving power of reversed-phase (RP) chromatography with the excellent selectivity and sensitivity of mass spectrometric detection. On the basis of comprehensive practical experience in the analysis of small molecules, pharmaceutical research is developing technologies for analysis of a growing number of peptidic drug candidates. This article is a detailed review of procedures based on LC–MS techniques for quantitative determination of peptides. With the focus on pharmaceutical applications several technologies for sample preparation, various aspects of peptide chromatography, important characteristics of ESI–MS, selectivity of MS-detection modes, the large variability of internal standards, and modern instrumentation are discussed. The demand for reliable, robust, sensitive, and accurate methods is discussed using numerous examples from the literature, complemented by experiments and results from our laboratory.     

Phase separation of poly(γ-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

Solvent effects on the phase separation of poly(-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, ₂ ^* , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed ₂ ^* value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed ₂ ^* values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the ₂ ^* value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, the ₂ ^* is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.The author is grateful to Mr. K. Sano and Mr. M. Watanabe for their observation of the liquid crystal formation.