Separation of phthalates by cyclodextrin modified micellar electrokinetic chromatography: Quantitation in perfumes

A new CE method has been developed for the simultaneous separation of a group of parent phthalates. Due to the neutral character of these compounds, the addition of several bile salts as surfactants (sodium cholate (SC), sodium deoxycholate (SDC), sodium taurodeoxycholate (STDC), sodium taurocholate (STC)) to the separation buffer was explored showing the high potential of SDC as pseudostationary phase. However, the resolution of all the phthalates was not achieved when employing only this bile salt as additive, being necessary the addition of neutral cyclodextrins (CD) and organic modifiers to the separation media. The optimized cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method consisted of the employ of a background electrolyte (BGE) containing 25 mM β-CD-100 mM SDC in a 100 mM borate buffer (pH 8.5) with a 10% (v/v) of acetonitrile, employing a voltage of 30 kV and a temperature of 25 °C. This separation medium enabled the total resolution of eight compounds and the partial resolution of two of the analytes, di-n-octyl phthalate (DNOP) and diethyl hexyl phthalate (DEHP) (Rs ~ 0.8), in only 12 min. The analytical characteristics of the developed method were studied showing their suitability for the determination of these compounds in commercial perfumes. In all the analyzed perfumes the most common phthalate was diethyl phthalate (DEP) that appeared in ten of the fifteen analyzed products. Also dimethyl phthalate (DMP), diallyl phthalate (DAP), dicyclohexyl phthalate (DCP), and di-n-pentyl phthalate (DNPP) were found in some of the analyzed samples.     

Application of carbon-based nanomaterials in sample preparation: A review

In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.     

Design and Synthesis of the First Thiophene Thioglycosides

A novel reported method for preparation of the first thiophene thioglycosides via a one-pot reaction of sodium thiophenethiolate salts with 2,3,4,6-tetra-O-acetyl-α-D-gluco- and galactopyranosyl bromides has been studied. The sodium thiophenethiolate salts were prepared using sodium cyanoethylene thiolate salts.     

Oxone-sodium nitrite mediated N-nitrosamines formation under mild conditions from secondary amines

Abstract

Herein, we report an efficient synthesis of N-nitrosamines from cyclic, aliphatic, benzylic, and aromatic secondary amines via a novel straightforward, efficient, and mild chemical process using sodium nitrite and Oxone in methanol as a solvent at 0–5?°C. The demonstrated methodology accounts well for the parameters like cost-effective, short reaction time, clean and safe handling along with good to excellent yields.     

High quality drug screening by capillary electrophoresis: A review

High quality assays are needed in drug discovery to reduce the high attrition rate of lead compounds during primary screening. Capillary electrophoresis (CE) represents a versatile micro-separation technique for resolution of enzyme-catalyzed reactions, including substrate(s), product(s), cofactor(s) and their stereoisomers, which is needed for reliable characterization of biomolecular interactions in free solution. This review article provides a critical overview of new advances in CE for drug screening over the past five years involving biologically relevant enzymes of therapeutic interest, including transferases, hydrolases, oxidoreductases, and isomerases. The basic principles and major configurations in CE, as well as data processing methods needed for rigorous characterization of enzyme inhibition are described. New developments in functional screening of small molecules that modulate the activity of disease-related enzymes are also discussed. Although inhibition is a widely measured response in most enzyme assays, other important outcomes of ligand interactions on protein structure/function that impact the therapeutic potential of a drug will also be highlighted, such as enzyme stabilization, activation and/or catalytic uncoupling. CE offers a selective platform for drug screening that reduces false-positives while also enabling the analysis of low amounts of complex sample mixtures with minimal sample handling.     

Solvent-Free NaHSO4-SiO2-Catalyzed Efficient Tetrahydropyranylation of Alcohols and Phenols

A simple and efficient tetrahydropyranylation of alcohols and phenols has been developed using NaHSO₄-SiO₂ (0.5 mol%) as a catalyst under solvent-free conditions to yield corresponding tetrahydropyranyl ethers in excellent yields.     

N-Phenylation of N-Arylaminophthalimides with Triphenylbismuth and Cupric Acetate: A Convenient Synthesis of 1-Aryl-1- Phenylhydrazines

Synthesis of 1-aryl-1-phenylhydrazines (2) from N-aryl-N-phenylaminophthalimides (1) which were synthesized by the phenylation of 1 with triphenylbismuth and cupric acetate is described.     

Solid Solutions of Calcium Aluminates C3A,C12A7 and CA with Sodium Oxide

The research concerns the influence of a substantial range of sodium ion concentrations on the structure of the calcium aluminates C₃A*, C₁₂A₇ and CA until CaO is emitted. The research also shows the influence of sodium ions of the cell parameters of each calcium aluminate and what reaction occur in mixtures of Na₂O and calcium aluminates at elevated temperatures. This revised version was published online in August 2006 with corrections to the Cover Date.     

Temperature dependence of the interaction between water and sodium polymethacrylate in water–methanol mixture

The information for the interaction between water molecules and a polyelectrolyte was obtained from ²³Na-NMR studies for sodium polymethacrylate in water-methanol mixtures. The chemical shift and the line width of the ²³Na nucleus give the information on the immediate magnetic environment and the motion of the nucleus, respectively. The change of the chemical shift for ²³Na nucleus is investigated by decreasing the temperature and changing the mol fraction of water in the solvent. According to these results, the hydrogen bonding of water molecules and polyanions becomes weaker as the temperature of the system decreases, but the interaction increases when the temperature is below the freezing point for water in this system. This effect, due to the change of temperature, becomes higher as the water mol fraction increases in the solvent. © 1995 John Wiley & Sons, Inc.