Syntheses of random PET‐co‐PTTs and some related copolyesters by entropically‐driven ring‐opening polymerizations and by melt blending: Thermal properties and crystallinity

A library of random poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and seven PET–PTT copolymers has been prepared in a high throughput manner by entropically‐driven ring‐opening polymerizations of the corresponding macrocyclic oligomers. The products have been investigated by differential scanning calorimetry and wide angle X‐ray diffraction. They show that the 50:50 copolymer displays a crystalline phase. The same phase can be formed by in situ transesterification when a 50:50 mixture of PET and PTT is melt blended. Poly(butylene terephthalate) (PBT)–PET and PTT–PBT 50:50 copolymers also show crystal phases. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Potassium Carboxylates by Direct Carbonylation of Potassium Alkoxides

Reaction of the K⁺ alkoxide of linalool ( 1 ) in benzene with CO at 425–440 bar and 120–130° for 12–30 h gave the K⁺ salt of 2,6-dimethyl-2-vinyl-5-heptenoic acid ( 4a ) in a ca. 25% yield based on ca. 65% converted alkoxide. Reaction of the [K⁺ ? 18-crown-6] alkoxide of 1 with CO at 50–55 bar and 40° for 90–140 h gave a mixture containing mainly the [K⁺ ? 18-c-6] salts of 4a (ca. 62%) and of the homogeranic acids 3a and 6a (together ca. 27% of the mixture) in a ca. 35% combined yield based on 50–60% converted alkoxide. The uncomplexed or complexed K⁺ alkoxide of (S)? 1 gave, with ca. 85% net retention, the K⁺ salt of (S)- 4a . Reaction of the [K⁺ ? 18-c-6] alkoxide of geraniol ( 2 ) with CO at 50 bar and 40° for 65–70 h gave myrcene ( 10 ) and geranyl formate ( 11 ) in a ca. 40–50% yield each based on ca. 85% converted alkoxide. Reaction of the [K⁺ ? 18-c-6] alkoxide of 3-pentyl-1,4-pentadien-3-ol ( 14 ) at 50 bar and r.t. for 70 h gave a mixture of the [K⁺ ? 18-c-6] salts of 2-pentyl-2-vinyl-3-butenoic acid ( 15a ) (67%) and the 4-pentyl-2,4-hexadienoic acids 18a and 19a (together 23% of the mixture) in a ca. 90% combined yield based on ca. 65% converted alkoxide.     

Design,Synthesis, and Anticancer Activities of Benzofuran–Isatin Hybrids Tethered by Pentylene and Hexylene

Fourteen benzofuran–isatin hybrids 6a – f and 7a – h tethered via alkyl linker (pentylene and hexylene) were designed and synthesized, and hybrids 6c – f and 7a – h were screened for their in vitro anticancer activity against various human cancer cell lines. The majority of the hybrids were active against the tested cancer cells, and the most active hybrids 7g (half maximal inhibitory concentration/IC₅₀: 77.2–88.9 μM) and 7h (IC₅₀: 65.4–89.7 μM), which possessed broad spectrum anticancer activity were as potent as the reference vorinostat (IC₅₀: 64.2–>100 μM) against all tested cancer cell lines, could act as leads for further investigations. The structure–activity relationship is also discussed, and the enriched structure–activity relationship may afford useful information for further rational design of the candidates with higher activity.     

Determination of cadmium, lead and copper in wine by potentiometric stripping analysis

A procedure for the determination of Cd, Pb and Cu in different wine samples after simple sample preparation on a mercury film electrode (MFE) by potentiometric stripping analysis (PSA) is presented. In 150 German wine samples collected in 1993/94 the following values were found: Cd mean: 0.63 ng/mL (range: 0.003– 0.98 ng/mL); Pb mean: 50 ng/mL (range: 4–254 ng/mL); Cu mean: 250 ng/mL (range: 50–394 ng/mL).     

Preparation of flexible and transparent polylactic acids films by crystallization manipulation

Highly flexible and transparent polylactic acids (PLAs) films were successfully prepared by manipulating their crystallization. The semicrystalline poly(L ‐lactic acid) (L) was blended with a noncrystalline poly(DL ‐lactic acid) (DL) together with diglycerol tetraacetate (DGTA). Optimal DGTA content to plasticize PLAs was about 17%. Addition of DL hindered the crystallization of the films. Tensile strengths of the films having DL content more than 5% were about 10 MPa while the elongations at break were boosted as DL content increased. Films having L/DL ratio of 50/50 showed elongations at break of 270%. Stretch ability and clarity of films containing 15–50% DL were fair although they were subjected to annealing at 60 °C for 1 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6489–6495, 2008     

Polarization studies by the TSC technique on a blend of cellulose acetate and polyvinyl acetate

The thermally stimulated current (TSC) technique has been used to study solvent-cast blends of a cellulose derivative with a vinyl polymer. TSC peaks are observed at 56, 80, and 120°C. Their origin is investigated because the TSC spectra of the blends differ from the spectra of the individual components. Data on blends with components in the weight ratios 25:75, 50:50, and 75:25 indicate that the 50:50 blend shows the greatest polarization. The enhancement of depolarization currents observed on blending is explained on the basis of a Maxwell–Wagner–Sillars polarization due to increased heterogeneity in the structure. Effects of forming conditions (time, temperature, field) on polarization have been investigated. Activation energies and relaxation times are calculated; there is good agreement between the values obtained from the initial-rise and the full-curve methods.     

The trace determination of some heavy metals in waters by flow-injection spectrophotometry and potentiometry

Three automated flow-injection systems are proposed for the determination of traces of manganese(II), lead and copper(II) in waters. The first system utilizes the catalytic effect of manganese(II) on the oxidation of N,N-diethylaniline by potassium periodate at pH 6.86–7.10 (30°C) and is used for spectrophotometric determination at 475 nm in the range 0.02–1.00 μg1^?1; the system involves reagent injection and stopped flow. The determination of lead in the range 0.7–100 μg1^?1 is based on spectrophotometric detection of the lead 4/(2-pyridylazo)resorcinol complex at 525 nm after on-line preconcentration of the sample (5–50 ml) on a minicolumn filled with Chelex-100 or Dowex 1-X8 resin. A potentiometric flow-injection system with a copper ion-selective electrode is applied for the determination of 0.5–1000 μg 1^?1 copper(II) after on-line preconcentration of 50–500 ml of sample on Chelex-100 resin. The procedures are tested on synthetic and real water samples, including sea water and waste-waters.     

Synthesis of poly(4‐vinylpyridine) by reverse atom transfer radical polymerization

Controlled radical polymerization of 4‐vinylpyridine (4VP) was achieved in a 50 vol % 1‐methyl‐2‐pyrrolidone/water solvent mixture using a 2,2′‐azobis(2,4‐dimethylpentanitrile) initiator and a CuCl₂/2,2′‐bipyridine catalyst–ligand complex, for an initial monomer concentration of [M]₀ = 2.32–3.24 M and a temperature range of 70–80 °C. Radical polymerization control was achieved at catalyst to initiator molar ratios in the range of 1.3:1 to 1.6:1. First‐order kinetics of the rate of polymerization (with respect to the monomer), linear increase of the number–average degree of polymerization with monomer conversion, and a polydispersity index in the range of 1.29–1.35 were indicative of controlled radical polymerization. The highest number–average degree of polymerization of 247 (number–average molecular weight = 26,000 g/mol) was achieved at a temperature of 70 °C, [M]₀ = 3.24 M and a catalyst to initiator molar ratio of 1.6:1. Over the temperature range studied (70–80 °C), the initiator efficiency increased from 50 to 64% whereas the apparent polymerization rate constant increased by about 60%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5748–5758, 2007     

Pharmacokinetics,bioavailability and metabolism of scopoletin in dog by ultra‐high‐performance liquid chromatography combined with linear ion trap–Orbitrap tandem mass spectrometry

A highly sensitive and selective method based on ultra‐high‐performance liquid chromatography combined with linear ion trap–Orbitrap tandem mass spectrometry (UHPLC–LTQ–Orbitrap–MS) has been developed and validated for the determination of scopoletin in dog plasma. The analyte was extracted from plasma samples using acetonitrile and separated on an Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm) with 0.05% ammonium hydroxide and acetonitrile as mobile phase. The developed method was linear over the concentration range of 1–500 ng/mL, with a correlation coefficient >0.9988. The intra‐ and inter‐day precisions (RSD) were <8.93% while the accuracy (RE) ranged from ?6.50 to 8.12%. Extraction recovery, matrix effect and stability for dog plasma samples were within the required limits. The validated method has been successfully applied to investigate the pharmacokinetics and metabolism of scopoletin in dog plasma after intravenous (1 mg/kg) and oral (10, 25, 50 mg/kg) administration. The results revealed that (a) scopoletin showed short elimination half‐life in dog; (b) its oral bioavailability was low (within the range of 5.69–7.08%); (c) scopoletin showed dose‐independent pharmacokinetic profiles in dog plasma over the dose range of 10–50 mg/kg; and (d) glucuronidation was the predominant metabolic pathway in dog.     

Determination of trans-Resveratrol in Bio-Matrices for in Vitro,ex Vivo,and in Vivo Pharmacokinetic Studies by LC Spectrometric Analysis

A high-performance liquid chromatography-electrospray ionization-mass spectromentry (LC–ESI–MS) method has been developed for the determination of picroside II in dog plasma. Plasma samples were deproteinated with acetonitrile and a Hypersil ODS2 column was used with a mobile phase consisted of methanol-water. The determination was validated in the concentration range of 0.10–50 μg mL⁻¹ using 50 μL of plasma. The method was successfully applied to a pharmacokinetic study of picroside II.

     

Luminol Chemiluminescence with Heteropoly Acids and its Application to the Determination of Arsenate,Germanate, Phosphate and Silicate by Ion Chromatography

A flow-injection chemiluminescence (CL) method has been proposed for sensitive determination of arsenate, germanate, phosphate and silicate, after separation by ion chromatography (IC). The post-column detection system involved formation of heteropoly acid in a H₂SO₄ medium before the CL reaction with luminol in an NaOH medium. For separation, heteropoly acid formation and the CL detection reaction, pH requirements were not compatible. When present as a heteropoly acid complex with molybdenum(VI), ger- manium(IV) and silicon(IV) caused CL emission from oxidation of luminol, and such a CL oxidation of luminol was observed analogously for arsenic(V) and phosphorus(V) but with the addition of metavanadate ion to the acid solution of molybdate. Good sensitivity for the three analytes arsenic(V), ger- manium(IV) and phosphorus(V) could be given by a single set of reagent conditions, chosen carefully. Another set was suitable for determining phosphorus(V) and silicon(IV). The minimum detectable concentrations of arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were 10, 50, 1 and 10 μg l⁻¹, respectively. Linear calibrations for arsenic(V), germanium(IV), phosphorus(V) and silicon(IV) were established over the respective concentration ranges of 10–1000, 50–25000, 1–1000 and 50–1 μg l⁻¹. The proposed IC–CL method was successfully applied to analyses of a seaweed reference material, rice wine and water samples.     

Determination of pyrethroid,organophosphate and organochlorine pesticides in water by headspace solid-phase microextraction

Simultaneous determination of pyrethroid, organophosphate (OP) and organochlorine (OC) pesticides in water was achieved with headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-electron-capture detection (GC-ECD). The parameters affecting HS-SPME of pesticides from water were optimized, including extraction temperature, sample and headspace volumes, and sodium chloride amounts. The effects of desorption temperature, desorption time, and position of the fibre in the GC inlet were also investigated. Extraction temperature was the most important factor affecting the recoveries of analytes, and the optimized temperature was 96°C. The addition of salt did not increase extraction efficiencies of the pesticides from the water. The optimized desorption conditions in the GC were as follows: desorption time of 10?min; desorption temperature of 260°C; and a 2?cm position of the fibre in the inlet. The method detection limits were in the low-ng/L level with a linearity range of 50–1000?ng/L for the OCs, 50–5000?ng/L for the OP, and 50–20?000?ng/L for the pyrethroids. These data demonstrated that HS-SPME is a sensitive method for the determination of pyrethroid, OC, and OP pesticides in water.     

Nanostructured thermoset epoxy resin templated by an amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) diblock copolymer

An amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) (PEO–PDMS) diblock copolymer was used to template a bisphenol A type epoxy resin (ER); nanostructured thermoset blends of ER and PEO–PDMS were prepared with 4,4′‐methylenedianiline (MDA) as the curing agent. The phase behavior, crystallization, hydrogen‐bonding interactions, and nanoscale structures were investigated with differential scanning calorimetry, Fourier transform infrared spectroscopy, transmission electron microscopy, and small‐angle X‐ray scattering. The uncured ER was miscible with the poly(ethylene oxide) block of PEO–PDMS, and the uncured blends were not macroscopically phase‐separated. Macroscopic phase separation took place in the MDA‐cured ER/PEO–PDMS blends containing 60–80 wt % PEO–PDMS diblock copolymer. However, the composition‐dependent nanostructures were formed in the cured blends with 10–50 wt % PEO–PDMS, which did not show macroscopic phase separation. The poly(dimethylsiloxane) microdomains with sizes of 10–20 nm were dispersed in a continuous ER‐rich phase; the average distance between the neighboring microdomains was in the range of 20–50 nm. The miscibility between the cured ER and the poly(ethylene oxide) block of PEO–PDMS was ascribed to the favorable hydrogen‐bonding interaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3042–3052, 2006     

Ultra-trace determination of Pb(II) and Cd(II) in drinking water and alcoholic beverages using homogeneous liquid-liquid extraction followed by flame atomic absorption spectrometry

The determination of Pb(II) and Cd(II) in different sample matrices, including drinking water, distilled spirits and fruit wine, was carried out by flame atomic absorption spectrometry (FAAS) after pre-concentration using homogeneous liquid-liquid extraction (HLLE). First, the HLLE method was optimised with lead diethyldithiocarbamate (Pb-DDTC) complex which was extracted with a perfluorooctanoate anion (PFOA^?) dissolved in lithium hydroxide under acidic conditions. The optimum extraction conditions, using 0.01 M DDTC, 0.05 M PFOA^?, 3 M HCl and 1 mL of 30 vol. % acetone, were obtained. The Pb-DDTC complex in the nitric acid digest of the samples (50–150 mL) was extracted quantitatively into a drop of 100 μL of sediment phase. The sediment phase dissolved in 1 vol. % HNO₃ with at least 3–5 mL of the final volume was then determined by FAAS, affording a pre-concentration factor of 10–50. Hence, the HLLE method afforded an increase in both sensitivity and selectivity for the metal determination by conventional FAAS, resulting in ultra-trace level detection of Pb(II) in all samples analysed (drinking water, 9.2–23 ng mL^?1; distilled spirits, 23–50 ng mL^?1; fruit wine, 24–53 ng mL^?1). In addition, the proposed method could successfully be applied to Cd(II) determination in these samples.     

Degradation of 2-nitrophenol from petrochemical wastewater by ozone

Russian Journal of Applied Chemistry - In this project, O3 process was used for degradation and mineralization of 50 mg L–1 of 2-nitrophenol (2NP) in a semi batch reactor under variable...     

Chemical fingerprint analysis and metabolic profiling of 50% ethanol fraction of Lomatogonium rotatum by ultra‐performance liquid chromatography/quadrupole–time of flight mass spectrometry

Lomatogonium rotatum (L.) Fries ex Nym (L. rotatum), a member of Gentianaceae, is an important mongolian medicine in China used to treat febrile diseases in liver and gallbladder. The aim of present study was to investigate the chemical constituents and metabolites of the 50% ethanol fraction of L. rotatum (50EtLR). Firstly, the extract of L. rotatum was partitioned by macroporous resin to obtain the target fraction (50EtLR), then several compounds were isolated from 50EtLR to obtained the standards for further analysis of chemical constituents of 50EtLR. Secondly, the chemical constituents of 50EtLR were characterized using the ultra‐high performance liquid chromatography coupled with quadrupole–time‐of‐flight mass spectrometry (UHPLC–Q‐TOF–MS/MS). Finally, prototype constituents and related metabolites were analyzed after orally administerng 50EtLR to rats. As a result, a new compound, 6‐O‐[β‐d ‐xylopyranosyl‐(1 → 6)‐O‐β‐d ‐glucopyranosyl]‐1,4,8‐trimethoxyxanthone ( 6 ) along with seven known compounds ( 1–5 , 7 and 8 ) were isolated from the 50EtLR, 92 components were either unambiguously or tentatively identified. Additionally, 34 prototype constituents and 112 metabolites in rat plasma along with 32 prototype constituents and 53 metabolites in rat liver were tentatively identified. Therefore, xanthones and flavonoids were the main chemical constituents of 50EtLR and sulfation and glucuronidation are the main enzyme‐induced metabolic pathways involved post‐administration.     

Measurement of quetiapine and four quetiapine metabolites in human plasma by LC-MS/MS

There is interest in monitoring plasma concentrations of N‐desalkylquetiapine in relation to antidepressant effect. A simple LC‐MS/MS method for quetiapine and four metabolites in human plasma (50 μL) has been developed to measure concentrations of these compounds attained during therapy. Analytes and internal standard (quetiapine‐d8) were extracted into butyl acetate–butanol (10:1, v/v) and a portion of the extract analysed by LC‐MS/MS (100 × 2.1 mm i.d. Waters Spherisorb S5SCX; eluent: 50 mmol/L methanolic ammonium acetate, pH* 6.0; flow‐rate 0.5 mL/min; positive ion APCI‐SRM, two transitions per analyte). Assay calibration (human plasma calibrators) was linear across the ranges studied (quetiapine and N‐desalkylquetiapine 5–800, quetiapine sulfoxide 100–15,000, others 2–100 µg/L). Assay validation was as per FDA guidelines. Quetiapine sulfone was found to be unstable and to degrade to quetiapine sulfoxide. In 47 plasma samples from patients prescribed quetiapine (prescribed dose 200–950 mg/day), the (median, range) concentrations found (µg/L) were: quetiapine 83 (7–748), N‐desalkylquetiapine, 127 (7–329), O‐desalkylquetiapine 12 (2–37), 7‐hydroxyquetiapine 3 (<1–48), and quetiapine sulfoxide 3,379 (343–21,704). The analyte concentrations found were comparable to those reported by others except that the concentrations of the sulfoxide were markedly higher. The reason for this discrepancy in unclear. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis of Ultraviolet-Absorbing Compounds in Human Urine by High Performance Liquid Chromatography

Abstract

Ultraviolet (UV)-absorbing compounds in human urine were analyzed by means of high-performance liquid chromatography using the column of macroreticular anion exchange resin maintained at 60°C. The sample was eluted with a linear gradient of water to 0.25 M ammonium perchlorate-acetonitrile (85:15) at 0–50 min and with 0.25 M ammonium perchlorate-acetonitrile (85:15) at 50–70 min and monitored with absorption at 254 nm. Reproducible chromatograms were obtained and 68 well resoluted peaks were numbered. The storage of a urine sample at ?-20°C for 7 weeks did not significantly affect the chromatogram. The correlation coefficients of every pair of the numbered peaks were calculated to examine the daily variations and the individual difference of the UV-absorbing urine components.     

Detecting Mechanochemical Degradation of Nitrocellulose by Combining Dynamic Mechanical Analysis with Mass Spectrometry

Summary: Dynamic mechanical analysis is combined with mass spectrometry to study nitrocellulose under oscillating strain. At a constant temperature (150–160 °C) and frequency (400–600 Hz) nitrocellulose fractures demonstrating a modulus drop and release of products with m/z: 30 and 44. At linear heating (2 °C · min⁻¹) and a frequency of 10–50 Hz similar products are released in two steps, the second of which demonstrates a modulus drop and a temperature increase indicating ignition.

Data for an isothermal dynamic mechanical analysis–mass spectrometry experiment performed at 160 °C.     

Determination of sulfonamide residues in cultured sea cucumber by pre-column derivatization capillary electrophoresis with fluorescence detection

A simple and mild method for the separation of sulfonamide residues based on a condensation reaction with O-phthalaldehyde solution (OPA) as labeling reagent with capillary electrophoresis has been developed. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, pH, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 20 mmol L^?1 borate buffer; pH 9.1; column temperature 20 °C; separation voltage 18 kV, pressure 50 mbar and injection time 8 s. Under the optimal conditions, 10 kinds of sulfonamide derivatives could be well-separated within 8 min, and the linear ranges were 0.35–100 μg kg^?1. The detection limit (at a signal-to-noise ratio of 3) was in the range of 0.12–0.25 μg kg^?1, and the quantification limit (at a signal-to-noise ratio of 10) was in the range of 0.35–0.70 μg kg^?1. The sulfonamide residues from cultured sea cucumber samples were determined under the optimal conditions with satisfactory results.