Switchable Hydrophilicity Solvent-Based Homogenous Liquid–Liquid Microextraction (SHS-HLLME) Combined with GC-FID for the Quantification of Methadone and Tramadol

In this work, a new method based on homogeneous liquid-phase microextraction was developed for the determination of methadone and tramadol. Dipropylamine was used as extraction solvent with switchable hydrophilicity that can be miscible/immiscible upon the addition or removal of CO₂ as a reagent. The effects of operational parameters of the extraction such as volume of acceptor phase, volume of donor phase, pH of donor phase, and ionic strength of solution were investigated. Under optimal conditions, the preconcentration factors, the detection limits and the linearity of the method were achieved in the ranges of 135–138, 1.2 and 4–1000 µg L^?1, respectively. Finally, the proposed method has been successfully applied to the analysis of methadone and tramadol in urine samples. In urine sample, the preconcentration factors were 118 and 122 for methadone and tramadol, respectively. Additionally, calibration curves were found to be linear in the concentration range of 8–1000 µg L^?1 with the r² values better than 0.998. In addition, limits of detection and quantification were 2.4 and 8 µg L^?1, respectively, for both analytes.     

Synthesis of 9-CD3-9-cis-retinal cofactor of isorhodopsin

We report the synthesis of 9-CD₃-9-cis-retinal via a six-step procedure from β-ionone. The steps involve an initial deuteration of the methyl ketone of β-ionone followed by two consecutive Horner-Wadsworth-Emmons (HWE) coupling reactions and their corresponding DIBAL reductions. A final oxidation of the allylic alcohol of the retinol leads to the target compound. This deuterium labeled retinoid is an important cofactor for studying protein-retinoid interactions in isorhodopsin.     

A novel optical sensor for uranium determination

A metal ion indicator, Alizarin Red S, was tested for its potential use in uranium selective optode membrane. The water-soluble indicator was lipophilized in the form of an ion pair with tetraoctylammonium bromide, and subsequently immobilized on a triacetyl cellulose membrane. The membrane responds to uranium ions, giving a color change from yellow to violet in acetate buffer pH 5. This optode has a linear range of (1.70-18.7) × 10⁻⁵ M of UO₂²⁺ ions with a limit of detection of 5 × 10⁻⁶ M. The response time of optode was within 6 min depending on the concentration of UO₂²⁺ ions. The sensor can readily be regenerated with hydrochloric acid solution (0.01 M). The optode is fully reversible.     

Screening of hepatitis B virus DNA in the serum sample by a new sensitive electrochemical genosensor-based Pd-Al LDH substrate

Journal of Solid State Electrochemistry - Screening for hepatitis B is one of the most severe liver virus infections in the world, and due to the effect of early detection and treatment of...     

A facile and effective procedure for synthesis of polyfunctionalized pyrrolines from simultaneously stirring of carbon disulfide,aniline, arylglyoxals and <Emphasis Type="Italic">β</Emphasis>-enaminocarbonyls

An efficient one-pot synthesis of 2H-pyrroline derivatives by a four-component reaction between carbon disulfide, aniline, arylglyoxals and β-enaminocarbonyls in acetonitrile at room temperature under mild reaction conditions is reported. The addition reaction has been done to access broad range of 5-hydroxy-4-phenylcarbamodithioate 2-H pyrroline derivatives after about 6 h stirring. All reactions were performed in acetonitrile at room temperature. Reactions are clean, and products were isolated by simple filtration.     

Characterization of a green and environmentally friendly sensitizer for a low cost dye-sensitized solar cell

Clean and cheap device, namely dye-sensitized solar cells (DSSCs) were fabricated using a natural dye extracted from Sambucus ebulus. We prepared five sample solutions with various pH in the extraction process to improve power conversion efficiency. The UV–visible absorption investigation of sample solutions and on photoanode show the dyes from J-type aggregation on a photoanode substrate. Redox properties of all sample solutions certify thermodynamically a charge transfer from excited state to conduction band TiO₂. The optical properties of various dye solutions were investigated and results showed darkness and bluish tint effect of dye solutions extracted in basic environment rather than those extracted in acidic condition. Moreover, in comparison to the basic condition, the dye solutions extracted in acidic environment were more saturated and colorimetrically less different from that one which extracted in neutral condition. Photophysical and photoelectrochemical performance of natural extraction dyes have been studied in dye-sensitized solar cell devices. The results show the rather high conversion efficiency of 0.57%, 1.15%, 1.02%, 0.35% and 0.15% of each individual dye extraction, respectively.     

How OH and O– groups affect electronic structure of meta-substituted and para-substituted phenols and phenolates

Structural Chemistry - An application of two independent quantum chemistry-based concepts, a substituent effect stabilization energy (SESE) and a charge of the substituent active region (cSAR), for...     

Pd(II) salen complex covalently anchored to multi‐walled carbon nanotubes as a heterogeneous and reusable precatalyst for Mizoroki–Heck and Hiyama cross‐coupling reactions

A Pd(II) salen complex anchored to multi‐walled carbon nanotubes showed excellent catalytic activity and stability for the Mizoroki–Heck and Hiyama cross‐couplings of aryl halides with olefins and phenylsiloxanes. Furthermore, the heterogeneous catalyst could be reused up to four times with the catalytic activity being recovered easily after simple manipulations. Copyright © 2014 John Wiley & Sons, Ltd.     

Highly sensitive electrochemical detection of dopamine and uric acid on a novel carbon nanotube-modified ionic liquid-nanozeolite paste electrode

A novel biosensor has been constructed by incorporating modified nanosized natural zeolite and 3-hydroxypropanaminium acetate (HPAA) as a novel room temperature ionic liquid, supported on multiwalled carbon nanotube (MWCNTs) and employed for the simultaneous determination of dopamine (DA) and uric acid (UA). A detailed investigation by transmission electron microscopy and electrochemistry is performed in order to elucidate the preparation process and properties of the composites. The voltammetric studies using the modified carbon paste electrode show two well-resolved anodic peaks for DA and UA with a potential difference of 160 mV, revealing the possibility of the simultaneous electrochemical detection of these compounds. The modified carbon paste electrode shows good conductivity, stability, and extraction effect due to the synergic action of HPAA, MWCNTs, and iron ion-doped natrolite zeolite. Under optimized conditions, the peak currents are linear from 8.12?×?10^?7 to 3.01?×?10^?4?mol?L^?1 and from 9.31?×?10^?7 to 3.36?×?10^?4?mol?L^?1 with detection limits of 1.16?×?10^?7 and 1.33?×?10^?7?mol?L^?1 for DA and UA using the differential pulse voltammetric method, respectively. Finally, the modified carbon paste electrode proved to have good sensitivity and stability and is successfully applied for the simultaneous determination of DA and UA in human blood serum and urine samples.