A novel and efficient one-pot strategy for the synthesis of 1,2,4-triazoles: access to synthesis of penipanoid A and its analogues.

We developed a novel one-pot strategy for synthesizing biologically important 1,2,4-triazole motifs from easily accessible 4-hydroxy phenylacetic acid, formamidine hydrochloride and hydrazine derivatives under mild conditions. This strategy enabled us to synthesize the natural penipanoid A and its analogues in one step.

Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone.

Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individually and simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II) to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximum absorbance of these complexes was found at 405 nm and 425 nm, respectively. For [Fe(II)-HNAHBH], Beer's law is obeyed over the concentration range of 0.055-1.373 µg mL(-1) with a detection limit of 0.095 µg mL(-1) and molar absorptivity ɛ, 5.6 × 10(4) L mol(-1) cm(-1). [Co(II)-HNAHBH] complex obeys Beer's law in 0.118-3.534 µg mL(-1) range with a detection limit of 0.04 µg mL(-1) and molar absorptivity, ɛ of 2.3 × 10(4) L mol(-1) cm(-1). Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content.

Stability indicating ion chromatography method for the simultaneous determination of ibandronate sodium drug substance and its impurities.

A simple and sensitive ion chromatography method has been developed for the simultaneous assay of ibandronate sodium drug substance and the determination of its impurities. The separation was achieved on Allsep™ anion column 150 mm × 4.6 mm, 7 µm particle diameter. The mobile phase consisted of 1% (v/v) aqueous formic acid and acetone 98:2% (v/v); flow rate 1.0 ml min(-1) at ambient temperature. The analytes were monitored by conductometric detector. The drug substance was subjected to stress conditions of hydrolysis, oxidation, photolytic, thermal and humidity degradation. Considerable degradation was achieved only under oxidative conditions. Mass balance was demonstrated in all stress conditions. The method was validated for specificity, precision, linearity, solution stability and accuracy. The limits of detection (LOD) and limits of quantification (LOQ) for impurities were in the range of 0.36-0.80 µg ml(-1) and 1.00-2.40 µg ml(-1), respectively. For ibandronate LOD was 38 µg ml(-1) and LOQ was 113 µg ml(-1). The average recoveries for impurities and ibandronate were in the range of 99.0-103.1% and the method can be successfully applied for the routine analysis of ibandronate sodium drug substance.

A stability-indicating liquid chromatographic method for Lomustine.

A simple, inexpensive and rapid liquid chromatography (LC) method has been developed for the quantitative determination of Lomustine, an chemotherapy drug. Degradation studies were performed on the bulk drug by heating to 60 °C, exposure to UV light at an energy of 200 Wh/m(2)and to visible light at an illumination of not less than 1.2 million lux hours, acid (0.1N hydrochloric acid), base (0.1N sodium hydroxide) aqueous hydrolysis and oxidation with 6.0% (v/v) hydrogen peroxide. Good resolution between the peaks corresponding to impurities produced during synthesis, degradation products and the analyte was achieved on a Symmetry C 8 LC column using a mobile phase consisting of a mixture of aqueous potassium dihydrogen phosphate and acetonitrile. The degradation samples were assayed against the reference standard of Lomustine and the mass balance in each case was close to 99.9%. Validation of the method was carried out as per International Conference on Harmonization (ICH) requirements.

Simultaneous Determination of Cobalt(II) and Nickel(II) by Fourth-Order Derivative Spectrophotometric Method Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone.

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in themixture are simultaneously determined without solving the simultaneous equations bymeasuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059-3.299 mug mL(-1) and 0.058-3.285 mug mL(-1) respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample.