Simultaneous high-performance liquid chromatographic determination of pioglitazone and metformin in pharmaceutical-dosage form

A simple, rapid, and precise method is developed for the quantitative simultaneous determination of metformin and pioglitazone in a combined pharmaceutical-dosage form. Separation is achieved with a Zorbax XDB C(18), 15-cm analytical column using buffer-acetonitrile (66:34, v/v) of pH 7.1, adjusted with orthophosphoric acid as the mobile phase. The buffer used in the mobile phase contains 10mM disodium hydrogen phosphate and 5mM sodium dodecyl sulphate in double-distilled water. The instrumental settings are flow rate of 1 mL/min, column temperature at 40 degrees C, and detector wavelength of 226 nm. The internal standard method is used for the quantitation of the ingredients of this combination. Methylparaben is used as an internal standard. The method is validated and shown to be linear for metformin and pioglitazone. The correlation coefficients for metformin and pioglitazone are 0.9991 and 0.9999, respectively. The relative standard deviations for six replicate measurements in two sets of each drug in the tablets are always less than 2%.     

Ion-pair extraction and determination of copper(II) and zinc(II) in environmental and pharmaceutical samples.

Copper and zinc were extracted from salicylate solution into Aliquat 336 dissolved in toluene and determined in the organic phase spectrophotometrically using 1-(2-pyridylazo)-2-naphthol. The determination of copper and zinc was also carried out titrimetrically or by atomic absorption spectrometry after stripping the metal ions from the organic phase. The method permits the determination of copper and zinc in environmental and pharmaceutical samples. The standard deviation and relative standard deviation are 0.052 micrograms and 0.69%, respectively, for copper and 0.041 micrograms and 0.60%, respectively, for zinc.     

Enantioselective synthesis of epi-(+)-Sch 642305: observation of an interesting diastereoselection during RCM

In an approach towards the enantioselective total synthesis of the novel bioactive natural product Sch 642305, an unusual diastereoselection during the key RCM reaction, resulted in the synthesis of the 11-epi-isomer of Sch 642305.     

Extraction and separation of uranium and lead with liquid anion-exchangers

A method is proposed for the extraction and separation of microgram amounts of uranium(VI) and lead(II) from sodium salicylate solution with high molecular-weight amines such as Aliquat 336, TOA, TIOA, Amberlite LA-1 or Amberlite LA-2 dissolved in xylene. From a critical study of pH, salicylate concentration, amine concentration, diluent and period of equilibration, the optimum conditions were identified. The method permits separation of uranium and lead from binary mixtures with metal ions commonly associated with them, the determination of uranium, and of lead in air samples.     

Water Formation for the Metalation of Porphyrin Molecules on Oxidized Cu(111)

Herein the formation of water molecules in the intermediate step of the redox reaction of porphyrins self‐metalation on O/Cu(111) is demonstrated. Photoemission measurements show that the temperature on which porphyrins pick‐up a substrate metal atom on O/Cu(111) is reduced by about 185±15 K with respect to the pure Cu(111). DFT calculations clearly indicate that the formation of a water molecule is less expensive than the formation of H₂ on the O/Cu(111) substrate and, in some cases, it can be also exothermic.     

Ultrasound-assisted synthesis of diversely functionalized tetrahydro-1H-Indole-4(5H)-one using Brønsted base silica sodium carbonate (SSC) as a catalyst under solvent-free conditions

An ultrasound-promoted, environmentally benign, efficient procedure has been developed for the synthesis of biologically active tetrahydro-1H-indol-4(5H)-one using heterogeneous Brønsted base silica sodium carbonate (SSC) as a catalyst under solvent-free conditions. In comparison to the conventional methods, this efficient green protocol provides remarkable advantages such as good to excellent yields, shorter reaction time, low cost, and easy workup procedure and bypasses the use of hazardous transition-metal catalysts and organic solvents.     

Design,synthesis, and antimicrobial activity of novel 5-substituted indole-2-carboxamide derivatives

Research on Chemical Intermediates - A series of novel, bioactive 5-substituted indole-2-carboxamide derivatives (10a–t and 14a–k) are synthesized by the coupling of 5-substituted...