Miscibility Studies of Dextran/Poly(vinyl pyrrolidone) Blend in Solution

The miscibility of dextran (Dex)/poly(vinyl pyrrolidone) (PVP) in solution has been investigated in different percentages of the blend components by employing viscosity, density, refractive index and ultrasonic velocity methods at 30 and 50°C, respectively. Ultrasonic velocity and adiabatic compressibility against blend compositions were plotted and found to be linear. The interaction parameters μ and α have been obtained by using the viscosity data. The results indicated that the Dex/PVP blends are miscible in the entire composition range and it was further confirmed by ultrasonic velocity, density, refractive index studies. In addition, the results revealed that the change in temperature has no significant effect on the miscibility of Dex/PVP polymer blend.     

Microwave‐synthesized Pepper Peduncle Carbon,Characterization, and Its Adsorption Studies

Adsorption on activated carbon is an efficient method for the removal of toxic dyes. However, since commercially available charcoal is quite expensive, activated carbon obtained from agricultural by‐products may serve as a good replacement. In this study, activated carbon was prepared from pepper peduncle, an agricultural waste product, by microwave activation. The synthesized carbon was characterized by X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis techniques. It was then used for the adsorption of methylene blue dye from an aqueous solution, which was studied as a function of the dye concentration, contact time, and temperature. The adsorption data were fitted to Freundlich and Langmuir isotherm models. The adsorption kinetics was studied by employing first‐ and second‐order kinetic models, and it was found that the adsorption of methylene blue on the synthesized activated carbon follows a second‐order kinetic model. Effect of temperature on the adsorption process was studied, and the thermodynamic parameters such as activation energy, change in enthalpy, entropy, and free energy of adsorption were calculated on the basis of the absolute theory of reaction rate expressions. About 99.5–91.8% of the dye was removed for an initial dye concentration in the range 20–100 mg/g in 1 h. Thus the synthesized activated carbon was found to be very efficient in adsorbing the dye.     

Indirect Spectrofluorimetric Determination of Piroxicam and Propranolol Hydrochloride in Bulk and Pharmaceutical Preparations

A simple and sensitive indirect spectrofluorimetric method for the assay of piroxicam (PX) and propranolol hydrochloride (PPH) in the pure form and in pharmaceutical formulations is proposed. This method is based on the oxidation of PX and PPH by a known excess of N-bromosuccinimide (NBS) followed by the reaction of the excess NBS with methdilazine hydrochloride (MDH) to yield fluorescent species. The fluorescence intensities were measured at 377 nm after excitation at 343 nm. The fluorescence intensities decrease linearly with an increase in concentration of PX and PPH over the ranges of 0.2–8.0 and 0.4–18.0 g/mL respectively. The common excipients and additives did not interfere in the determination. The proposed method has been successfully applied for the determination of PX and PPH in pharmaceutical formulations. The results have been validated by statistical data.     

Organic semiconductors—metal phthalocyanine sheet polymers

This publication discusses the electronic, magnetic susceptibility, MS and GC–MS pyrolysis, X-ray powder diffraction, and electrical conductivity studies on metal phthalocyanine sheet polymers. The magnetic measurements over the range of magnetic field strengths 1025–6144 gauss indicated the absence of the intermolecular cooperative effect. MS and GC–MS studies indicate that all these metal phthalocyanine sheet polymers give benzene, cyanobenzene, and dicyanobenzene on thermal degradation. The electrical conductivity measurements showed that these polymers are semiconductor in nature.     

MS and GC–MS studies on phthalocyanine monomers

Phthalocyanines are a class of macrocyclic organic compounds known for their high tinctorial properties, thermal stability, chemical inertness, catalytic activity, and photoconductivity. A mass spectral study on metal phthalocyanines presented many difficulties because of their excellent thermal stability. The present work deals with MS and GC–MS studies of phthalocyanine, copper, and nickel phthalocyanine monomers at various temperatures. Tentative mechanism for the modes of fragmentation is proposed.     

Effect of method of preparation and process variables on controlled release of insoluble drug from chitosan microspheres

An inexpensive and simple method was adopted for the preparation of chitosan microspheres, crosslinked with glutaraldehyde (GA), for the controlled release of an insoluble drug‐ibuprofen, which is a commonly used NSAID (non‐steroidal anti‐inflammatory drug). The chitosan microspheres were prepared by different methods and varying the process conditions such as rate of stirring, concentration of crosslinking agent, and drug:polymer ratio in order to optimize these process variables on microsphere size, size distribution, degree of swelling, drug entrapment efficiency, and release rates. The absence of any chemical interaction between drug, polymer, and the crosslinking agent was confirmed by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA) techniques. The microspheres were characterized by optical microscopy, which indicated that the particles were in the size range of 30–200 µm and scanning electron microscopy (SEM) studies revealed a smooth surface and spherical shape of microspheres. The microsphere size/size distributions were increased with the decreased stirring rates as well as GA concentration in the suspension medium. Decreasing the concentration of crosslinker increased the swelling ratio whereas extended crosslinking exhibited lowered entrapment efficiency. The in vitro drug release was controlled and extended up to 10 hr. Copyright © 2007 John Wiley & Sons, Ltd.     

Spectrophotometric investigations of the assay of physiologically active catecholamines in pharmaceutical formulations

Two simple, sensitive, and accurate spectrophotometric methods are proposed for the determination of levodopa (LD), methyldopa (MD), dopamine hydrochloride (DP), and pyrocatechol (PC) in pure and pharmaceutical preparations. The methods are based on measurement of the absorbances of tris(o-phenanthroline)iron(II) (method A) and tris(bipyridyl)iron(II) (method B) obtained by the oxidation of the catecholamines by iron(III) in the presence of 1,10-phenanthroline and 2,2'-bipyridyl at 510 and 522 nm, respectively. The absorbances were found to increase linearly with increases in the concentrations of the catecholamines, results which were corroborated by the calculated correlation coefficients (0.9990-0.9996). Beer's law was valid over the concentration ranges of 0.04-0.6, 0.06-0.75, 0.06-0.65, and 0.05-0.70 microg/mL in method A and 0.02-1.0, 0.04-1.3, 0.05-1.0, and 0.06-1.1 microg/mL in method B for PC, MD, LD, and DP, respectively. The common excipients and additives did not interfere in their determinations. The proposed methods were successfully applied to the assay of LD, MD, and DP in various dosage forms. The results were validated by statistical analysis.     

Synthesis,structural investigations and biological studies on symmetrically substituted 3,3′,3",3"′-tetra-methoxyphenylimino phthalocyanine complexes

The present paper describes the synthesis and characterization of novel metal (II) 3,3′,3″,3‴-tetramethoxyphenylimino substituted phthalocyanines (M-MeOPhImPcs) of copper (II), cobalt (II), nickel (II) and zinc (II) by condensing the 3,3′,3″,3″′-tetra amino phthalocyanines with anisaldehyde. The dark bluish green colored tetraimino substituted phthalocyanine derivatives were characterized by various physico-chemical techniques like elemental analysis, magnetic susceptibility, electronic, IR, powder X-ray diffraction and thermo gravimetric analysis (TGA) to check the structural integrity and purity. The variations of magnetic moment as a function of field strength indicated the presence of inter molecular co-operative interactions. The complexes were also evaluated for their antifungal and antibacterial activities. This article was submitted by the authors in English.     

Synthesis and spectroscopic investigations of iron(III) complexes with chlorides and dianionic,symmetrically halogen substituted phthalocyanines as ligands

The synthesis of iron(III) complexes of general formula FeCl(R-pc), where R-pc are dianionic, symmetrically halogen substituted phthalocyanines at the positions 2,9,16,23 or 1,8,15,22, from the corresponding amino substituted derivatives is described (R=Cl, Br, I). The complexes are characterized by UV-visible and infrared spectra, powder X-ray diffraction and magnetic susceptibility measurements. The effect of substituents at the periphery and the basicity of the solvents used on the electronic spectra are discussed. The Q band of the electronic spectra for symmetrically halogen substituted derivatives are redshifted and the substituents at 2,9,16,23- positions are more effective in redshifting the Q bands than those at 1,8,15,22-positions. Depending upon the basicity of the solvents, the ligand-to-metal charge transfer (LMCT) transitions on Q band envelop shift to the higher energy region in the order of pyridine>DMF>DMSO. The infrared absorption signals for C-H and metal-ligand vibrations appear to be sharper for 1,8,15,22 substituted derivatives than for 2,9,16,23 substituted ones.