Transition Metal Complexes of Ethopropazine: Synthesis and Characterization

Abstract Ethopropazine (EP) or profenamine is a phenothiazine derivative, N 10 -(2-diethylaminopropyl)phenothiazine

Rapid ultra-performance liquid chromatography assay of losartan potassium in bulk and formulations

Background: Losartan potassium is a non-peptide AT1 receptor drug used in the treatment of hypertension. Methods: A simple, rapid, sensitive, and validated isocratic reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed and validated for the determination of losartan potassium (LOS) in bulk drug and tablets. The assay was developed using Waters Acquity BEH C18 (100 mm × 2.1 mm), 1.7-μm column with a mobile phase consisting of a mixture of phosphate buffer (pH 3.2) and acetonitrile (50:50 v/v). Results: An assay with a total run time of only 5 min was developed. The method monitored at 245 nm exhibited linearity over a concentration range of 2.0 to 15.0 μg mL−1 LOS. The limits of detection and quantification (signal-to-noise ratio (S/N) = 10) were found be 0.018 and 0.054 μg mL−1 , respectively. The intraday and interday RSDs were less than 1.0%. The method was validated by the determination of LOS levels in tablets where the percentage on the label claim was 100 ± 2. The accuracy of the method was further ascertained by recovery studies via the standard addition procedure, which yielded satisfactory results. Conclusion: A rapid UPLC assay of LOS in bulk drug and tablets was developed and validated

Synthesis of chromium(III) oxide nanoparticles by electrochemical method and mukia maderaspatana plant extract, characterization, KMnO4 decomposition and antibacterial study

Chromium oxide nanoparticles were synthesized by the reduction of potassium dichromate solution with Mukia Maderaspatana plant extract. In electrochemical methods, Cr2O3 nanoparticles were synthesized by two ways, using platinum (Pt) electrodes and K2Cr2O7 solution with H2SO4 as medium in the first case. And chromium doped platinum electrode (Pt/Cr) in presence of NaHCO3 solution in second case. The resulting Cr2O3 nanoparticles were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV-VIS absorption and Fourier-transform infrared (FTIR) spectroscopy. The enhancing influence of Cr2O3 nanoparticles as a catalyst for the decomposition of KMnO4 has been studied. The antibacterial effect of Cr2O3 nanoparticles against E. coli was investigated. These particles were shown to have an effective bactericide

Ethylisobutrazine hydrochloride as a selective and sensitive reagent for the spectrophotometric determination of vanadium(V) and its application to vanadium-bearing minerals and alloys

Ethylisobutrazine hydrochloride is proposed as a selective and sensitive reagent for the spectrophotometric determination of vanadium(V). It forms a red-colored species with vanadium(V) in 3.5-6.5 M phosphoric acid medium. An eight-fold molar excess of reagent is necessary for the full development of the color. The red species exhibits an absorption maximum at 518 nm with a molar absorptivity of 9.75 � 103 liters mol-1 cm-1. Sandell's sensitivity is 5.2 ng cm-2. Beer's law is obeyed over the range 0.1-6.2 ppm of vanadium(V) with an optimum concentration range of 0.4-6.0 ppm. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions, are reported. The method has been used successfully for the determination of vanadium in ilmenite and vanadium steels that contain chromium, molybdenum, manganese, nickel, copper, tungsten, and titanium. © 1985

Kinetic and mechanistic study of oxidation of piperazines by bromamine-T in acidic medium

Oxidations of piperazine, 1-methylpiperazine and 1-ethylpiperazine by bromamine-T (BAT) in buffered acidic medium have been kinetically studied at 303 K. The reaction shows a first-order dependence of the rate each on [BAT]0 and [piperazine]0, and an inverse fractional-order dependence on [H+ ]. The additions of halide ions and the reduction product of BAT, p-toluenesulfonamide, have no effect on the reaction rate. The variation of ionic strength of the solvent medium has no influence on the rate. Activation parameters have been evaluated from the Arrhenius and Eyring plots. A common mechanism consistent with the kinetic data has been proposed for all piperazines. The protonation constants of substrates have been evaluated. The Hammett linear free-energy relationship has been observed for the reaction with ρ = −0.5 indicating that the electron-donating groups enhance the reaction rate by stabilizing the transition state. An isokinetic relationship observed shows β = 368 K indicating the dominance of enthalpy factors on the reaction rate

Rapid spectrophotometric determination of cerium(IV), arsenic(III), and nitrite with perphenazine

Perphenazine dihydrochloride, PPN, is proposed as a new reagent for the spectrophotometric determination of cerium(IV), arsenic(III), and nitrite. The reagent forms a red-colored species with cerium(IV) instantaneously in 3.5-5.5 M phosphoric acid medium. The red species exhibits maximum absorbance at 516 nm. A 15-fold molar excess of PPN is necessary for the full development of the color intensity. Beer's law is obeyed over the cerium concentration range 0.4-20 ppm and Sandell's sensitivity is found to be 0.016 μg/ cm2. The effects of acidity, time, order of addition of reagents, temperature, reagent concentration, and diverse ions are reported. The proposed method offers the advantages of good sensitivity, simplicity, rapidity, selectivity, and a wider range of determination without the need for heating or extraction. Arsenic(III) and nitrite are also indirectly determined. The method is extended to the determination of cerium content in synthetic mixture corresponding to misch metal. © 1985

N-Bromosuccinimide assisted oxidation of hydrophobic tetrapeptide sequences of elastin: A mechanistic study

The repeating sequences of elastin, glycyl–glycyl–alanyl–proline (GGAP) glycyl–glycyl–isoleucyl–proline (GGIP) and more hydrophobic glycyl–glycyl–phenylalanyl–proline (GGPP), were synthesized by classical solution phase methods and characterized. The kinetics of oxidation of tetrapeptides (TPs) and their constituent amino acids (AAs) by N-bromosuccinimide (NBS) was studied in the presence of perchlorate ions in acidic medium at 28°C. The reaction was followed spectrophotometrically at λmax=240nm. The reactions follow identical kinetics, being first order each in NBS, AA and TP. No effect on the rate of H+, reduction product succinimide and ionic strength was observed. Effects of dielectric constant of the medium and the added anions such as chloride and perchlorate were studied. Activation parameters have been computed. The oxidation products of the reaction were isolated and characterized. The proposed mechanism is consistent with the experimental results. An apparent correlation was noted between the rate of oxidation and the hydrophobicity of AAs and TPs

Application of Azure C for the extractive spectrophotometric determination of microgram amounts of penicillin

A simple, accurate, and rapid method for the quantitative determination of penicillin is proposed. The method is based on the formation of a blue penicillin-Azure-C ion-pair that can be extracted into chloroform in phosphate-citric acid buffer. The molar absorptivities for sodium penicillin G and potassium penicillin V at 635 nm were 5.46 � 103 and 2.19 � 104 l/mol/cm, respectively. Beer's law was valid over the concentration range of 4-80 μg ml for sodium penicillin G and 3-55 μg ml for potassium penicillin V. Maximum absorbance was obtained almost instantaneously and was stable for several days. The method was successfully applied to pharmaceutical preparations. © 1985

Ruthenium(III) catalyzed oxidation of indigo carmine by manganese(III) in sulfuric acid medium: a kinetic and mechanistic study

Aims: Reactions of manganese(III)-porphyrins have been reported as possible models for closely related and biologically significant systems. Method: In this study, a stock solution of manganese(III) sulfate was prepared using a standard method of anodic oxidation of manganese(II) in H2SO4. The Indigo carmine (IC)-Mn(III) reaction catalyzed by Ru(III), under pseudo-first-order conditions, has been spectrophotometrically monitored at the IC λmax IC (610 nm) at constant temperature. The experimental rate law for the reaction is: rate = k' [IC][H+]x[Ru(III)]y, where x and y are fractional orders. Objective: The reaction rate shows a zero-order dependence on the concentration of the oxidant, Mn(III), indicating its involvement in fast steps following the slow step. Additionally, the effect on the rate of adding the reduction product, Mn(II), has been found to be negligible. Variations of the ionic strength and the dielectric constant of the reaction medium have negligible effect on the rate. Result: Based on the effect of temperature, activation parameters have been evaluated using Arrhenius and Erying plots. A suitable mechanism has been presented. The rate law derived is consistent with experimental data