P. Raveendra Reddy

Direct and Derivative Spectrophotometric Determination of Copper(II) with 5-Bromosalicylaldehyde Thiosemicarbazone

A rapid and sensitive spectrophotometric method is developed for the determination of Copper (II) in aqueous DMF medium. The metal ion forms a light greenish yellow coloured complex with 5-bromo salicylaldehyde thiosemicar- bazone (5-BSAT) in acidic medium. The complex shows absorption maximum at 390nm. Beers law is obeyed in the range 0.31 - 6.35 � gml -1 of Copper (II). The molar absorptivity (� ) and Sandells sensitivity are found to be 1.08 X 10 4 l mole -1 cm -1 and 0.062 � gcm -2 respectively. A method for the determination of copper by third derivative spectrophotome- try is also proposed. The methods have been employed successfully for the determination of copper in grape leaves and aluminum based alloy samples.

Simple and Simultaneous Method for Determination of Palladium(II) and Ruthenium(III) using Second-Order-Derivative Spectrophotometry

Abstract A simple, sensitive, and selective second-order-derivative spectrophotometric method has been developed for the simultaneous determination of palladium(II) and ruthenium(III) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent (HMBATSC) reacts with Pd(II) and Ru(III) at pH 3.0, forming soluble yellowish green and dark brown species, respectively. Palladium and ruthenium present in the mixture were simultaneously determined without solving the simultaneous equations by measuring the second derivative amplitudes at 445 nm and 385 nm, respectively. Further, the Beers law was obeyed in the range 0.21–12.78 µg mL−1 and 0.25–13.42 µg mL−1 for Pd(II) and Ru(III), respectively. A large number of foreign ions did not interfere in the present method. The proposed method was successfully applied for the determination of palladium in hydrogenation catalysts and ruthenium in water samples.

Development of a Rapid and Sensitive HPLC Assay Method for Lenalidomide Capsules and Its Related Substances

A chromatographic method was established for the determination of lenalidomide and related substances in 10 mg and 5 mg capsules using Sunfire C-18(250×4.6 mm ID, 5 μm) HPCL column with 85:15 v/v ratio of mobile phases A (mixture of phosphoric acid buffer and 1-octane sulphonic acid sodium salt) and B(55: 45 v/v ratio of methanol and acetonitrile) at 40°C and 210 nm wave length. The degradation studies were performed using 0.1N HCl, 0.1 N NaOH, 1% v/v hydrogen peroxide, humidity, UV at 254 nm, Sun light, and heat to 60°C. No significant degradation of lenalidomide was observed. However, the slight degradation was observed in presence of NaOH. The developed HPLC method gave the peaks purity angle was less their threshold angle, indicating it to be suitable for stability studies. It was validated with respect to linearity, accuracy, precision, ruggedness, and robustness.

First Order Derivative Spectrophotometric Determination of Vanadium(V) and Iron(III) Individually and Simultaneously

A novel, sensitive and highly selective first derivative spectrophotometric method is proposed for the determination of vanadium(V) and iron(III) metal ions separately and simultaneously in a mixture. 2-Hydroxy-1-naphthaldehyde benzoylhydrazone (OHNABH) reacts with vanadium(V) and iron(III) in sodium acetate–acetic acid buffer medium (pH 5.0) forming yellow and yellowish brown colored soluble complexes, respectively. The first derivative curves of these colored solutions show maximum derivative amplitudes at 465 nm (V(V)) and 540 nm (Fe(III)) obeying Beers law in the range 0.12–2.50 μg ml–1 and 0.14–4.20 μg ml–1, respectively. Large number of foreign ions do not interfere in the present method. A very simple and accurate simultaneous first derivative method is also reported for the determination of V(V) and Fe(III) in mixtures without solving simultaneous equations. The method is applied for the analysis of various natural samples, food and biological materials.

DIRECT AND SECOND DERIVATIVE SPECTROPHOTOMETRIC DETERMINATION OF MOLYBDENUM (VI) IN FOOD STUFFS AND IN ALLOY STEELS USING 2- HYDROXY-3-METHOXY BENZALDEHYDE THIOSEMICARBAZONE (HMBATSC)

A rapid, simple, sensitive and selective spectrophotometric method is developed for the determination of molybdenum (VI) in aqueous dimethyl formamide (DMF). Molybdenum (VI) forms a yellow coloured complex with 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone in the pH range 1.0-6.0. The complex shows maximum absorbance at 375nm and in the pH range 1.0-2.0. However, at this wave length, the reagent shows considerable absorbance. At 385nm, the complex shows large absorbance while the reagent blank shows negligible absorbance. Hence, analytical studies are carried out at 385nm and at pH 1.5 against reagent blank. Beers law is obeyed in the range 0.24-4.32 µg ml-1. The molar absorptivity and Sandells sensitivity forthe coloured solution are found to be 2.3 x 10-4 1 mol-1 cm-1 and 0.0042 µg cm-2 respectively. The interference effect of various diverse ions has been studied. The complex shows 1:1 [Mo (VI): HMBATSC] stoichiometry with a stability constant 2.35 x 106. The standard deviation of the method in the determination of 2.396 µg ml-1 of Mo(VI) is calculated as ± 0.0012. A second order derivative spectroscopic method is developed for the determination of molybdenum(VI), which is more sensitive than the zero order method.. The developed method has been employed for the determination of molybdenum (VI) in food stuffs and in alloy steels. The results are in excellent agreement with the certified values

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 Beers law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299 μg mL−1 and 0.058–3.285 μg 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.

Erratum to: Direct and derivative spectrophotometric determination of thorium with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone

A simple and sensitive spectrophotometric method is developed for the determination of throium in aqueous medium. The metal ion forms yellow coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2.0–8.0. The complex shows an absorption maximum at 390 nm. The absorbance of the complex is maximum at pH 5.5 Beers law is obeyed in the range 0.30–7.00 μg/ml of thorium(IV). The molar absorptivity and the Sandells sensitivity of the method are 2.20· 104 l·mol−1·cm−1 and 0.0106 μg/cm−2, respectively. The interference of various ions was studied. The composition of the complex is 1:1 {Th(IV) : 2,4-DHBINH}. The first derivative spectrum of the complex shows a zero cross at 391.2 nm and maximum amplitude at 415 nm. Thus a sensitive derivative spectrophotometric method for the determination of Th(IV) is proposed.

A Rapid and Simple Spectrophotometric Determination of Traces of Chromium (VI) in Waste Water Samples and in Soil samples by using 2-Hydroxy, 3-Methoxy Benzaldehyde Thiosemicarbazone (HMBATSC)

A rapid and simple Spectrophotmetric method has been developed for the determination of microgram amount of Chromium (VI) in aqueous dimethyl formamide (DMF). Chromium (VI) forms a yellowish green coloured M:L complex with 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone in the acidic buffer medium (pH=6.0) at room temperature. The complex shows maximum absorption at 385nm. Beers law is obeyed in the range 0.260 to 2.60 

Synthesis and in silico studies of pyrrolidine sulfonamide based dipeptides as β-gluscosidase inhibitors

A series of novel pyrrolidine sulfonamide derivatives were designed, synthesized and screened in silico for their β-gluscosidase inhibitory activity. The results showed that the pyrrolidine derivatives exhibited moderate inhibitory activity against human β-gluscosidases inhibitors. The structure-activity relationships were also briefly discussed. The studies indicated that compounds of Series B with imidazole sulfonyl group were the most potent inhibitors compared to the other compounds under investigation.

Spectrophotometric Determination of Gold(III) Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone as a Chromophoric Reagent

A chromophoric reagent, 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC), was employed for the sensitive spectrophotometric determination of gold(III). The gold(III) ion forms a blue-coloured complex with HMBATSC in an aqueous dimethyl formamide at pH 6.0. The gold complex shows the absorption maximum at 385 nm, and Beers law was obeyed in the range 0.49–8.37 μg mL−1. The molar absorptivity and Sandells sensitivity were found to be 1.28×104 L mol−1 cm−1 and 0.015 μg cm−2, respectively. The complex shows 1 : 1 [Au(III) : HMBATSC] stoichiometry with a stability constant of 1.32×106. The interference effect of various diverse ions has been studied. In addition to zero-order, first- and second-order derivative spectrophotometric methods were also developed for the determination of gold(III) in microgram amounts which were more sensitive than the zero-order method. The developed method has been used for the determination of gold(III) in environmental water samples and certified reference materials. The results were in excellent agreement with the certified values.