Spectrophotometric estimation of risperidone in tablets.

A simple, rapid and highly sensitive spectrophotometric method is developed for the determination of risperidone in tablet formulation. The method is based on the oxidation of drug using potassium permanganate in alkaline medium and excess potassium permanganate oxidizes 1,10-phenanthroline Fe(II). The measurement of decrease in absorbance of 1,10-phenanthroline Fe (II) was done at 415 nm. The beer's law is obeyed in the concentration range of 5.0 to 40.0 µg/ml and molar absorptivity is found to be 7.3932 × 10(4) l/mol/cm. The proposed method is well suited for the pharmaceutical formulations.

Redox spectrophotometric method involving electrolytically generated manganese(III) sulphate with diphenylamine for the determination of ascorbic acid present in the samples of various fruits, commercial juices and sprouted food grains.

A spectrophotometric method was developed for ascorbic acid present in various fruits, commercial fruit juices and sprouted food grains. The method involves the oxidation of ascorbic acid with excess manganese(III) following reduction of unreacted manganese(III) with diphenylamine or barium diphenylamine sulphonate forming a product λ(max) 570 nm the system 1 or 540 nm the system 2 and decrease in the colour intensity is proportional to the concentration of vitamin C with quantification range 0.3-3.0 µg ml(-1). The molar absorptivity and Sandell's sensitivity values of the system 1 and the system 2 were 1.829 × 10(4) and 1.813 × 10(4)mol(-1)cm(-1) and 0.0096 and 0.0097 µg cm(-2) respectively. The stoichiometry was 4:1 between manganese(III) and diphenylamine. The ascorbic acid contents of the same samples were determined separately following the procedures of the developed method as well as the reference method and the results were comparable.

New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg.

The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with λ(max) 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine λ(max) 570 the system 3/barium diphenylamine sulphonate λ(max) 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 µg ml(-1)/0.14-1.40 µg ml(-1).

Spectrophotometric estimation of azithromycin in tablets.

The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 µg/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated.

Iron(III) oxidized nucleophilic coupling of catechol with o-tolidine/p-toluidine followed by 1,10-phenanthroline as new and sensitivity improved spectrophotometric methods for iron present in chemicals, pharmaceutical, edible green leaves, nuts and lake water samples.

A nucleophile formed from iron(III) oxidized catechol in 0.1M hydrochloric acid couple with o-tolidine, system 1/p-toluidine, system 2 to produce dye product, λ max 520 nm. The system 1/2 obeys Beer's law in the range 0.08-8.0 µg ml(-1) with molar absorptivity, Sandell sensitivity and regression coefficient values, 4.225 × 10(3)/3.140 × 10(3) l mol(-1) cm(-1), 0.0132/0.0178 µg cm(-2) and 0.9987/0.9981. Iron(II) formed from iron(III) in system 1/2 reacts with 1,10-phenanthroline, λ max 510 nm, will constitute sensitivity improved iron determinations with values 0.08-1.6 µg ml(-1), 2.4136 × 10(4)/2.2511 × 10(4) l mol(-1) cm(-1), 0.0023/0.0025 µg cm(-2) and 0.9980/0.9997 corresponding to range, molar absorptivity, Sandell sensitivity and regression coefficient. The results of the systems for iron present in chemicals, pharmaceutical, edible green leaves, nuts and lake water samples are satisfactory since they are comparable with the results of iron determined separately from 1,10-phenanthroline method.

A simple spectrophotometric method for the determination of phosphate in soil, detergents, water, bone and food samples through the formation of phosphomolybdate complex followed by its reduction with thiourea.

A simple spectrophotometric method is developed here for the determination of phosphate present in the samples of soil, detergents, water, bone and food based on the formation of phosphomolybdate complex with the added molybdate followed by the reduction of the complex with thiourea in aqueous sulfuric acid medium. The system obeys Beer's law at 840 nm in the phosphate concentration range, 0.5-10.0 µg/ml. Molar absorptivity, correlation coefficient and Sandell's sensitivity values are found to be 1.712 mol(-1) cm(-1), 0.9769 and 0.0555 µg cm(-2) respectively. For a comparison of the results determined from the developed method, phosphate present in the same set of samples is determined separately following an official method. The results of the developed method are agreeing well with those of the official phosphomolybdate method.

A simple and rapid spectrophotometric method for the determination of nitrite by its decolorizing effect on peroxovanadate complex.

A rapid, simple, and most economical spectrophotometric method was proposed for the determination of nitrite in various water samples, soil samples, and roots of leguminous plants. The method is based on decolorizing effect of nitrite on complex formed between hydrogen peroxide and vanadate in acidic medium. The decolorization of that complex by nitrite was exploited to monitor the reaction spectrophotometrically at 470 nm. The method was optimized for effect of concentrations of ammonium metavanadate, hydrogen peroxide, various acids, concentrations of sulphuric acid, order of reagents addition and color stability. The color of the complex was found to be stable for about 2 days, and the stability constant of the complex was also calculated by modified Job's method. The linearity range of the calibration graph was over 6.67-66.7 microg ml(-1) of nitrite with molar absorptivity, 0.276 x 10(3) mol(-1) l cm(-1) and Sandell's sensitivity, 0.1667 microg cm(-2). The method was applied successfully for the determination of nitrite in soil samples, various wastewater samples and roots of leguminous plants.

Degradation of carboxin (Vitavax) and oxycarboxin (Plantvax) by Pseudomonas aeruginosa isolated from soil.

Pseudomonas aeruginosa capable of utilizing carboxin and oxycarboxin as sole sources of carbon and nitrogen was isolated from red sandy loam soil perfused with the solutions of these fungicides. The bacterium hydrolyzed oxycarboxin via the intermediate compound 2-(vinylsulphonyl) acetanilide liberating 2- (2-hydroxyethylsulphonyl) acetic acid and aminophenol, whereas carboxin was first oxidized to its sulphoxide and then to its sulphone before hydrolysis. Further hydrolysis of aminophenol by the organism resulted in the accumulation of ammonium which was partly oxidized to nitrite. Nitrite accumulated in the medium without further oxidation to nitrate.