Dr. Rameswara Rao Modalavalasa - Academia.edu (original) (raw)

Research Articles - Published Papers by Dr. Rameswara Rao Modalavalasa

A novel simple, user friendly and stability representing high performance liquid chromatographic ... more A novel simple, user friendly and stability representing high performance liquid chromatographic method for estimation of dapagliflozin in API and pharmaceutical forms was developed and validated. A Phenomenex Gemini-NX C18 Column (250 mm length, 4.6 mm diameter, 5 μm particle size) with a mobile phase containing of Methanol: Sodium 1-octanesulphonate in the proportion of 70:30 v/v was utilized for the chromatographic elution study. An injection volume of 20 μl with a flow rate of 1.0 ml/min was chosen for this investigation and the created technique was validated with various parameters like: Linearity, Limit of Detection (LOD), Limit of Quantification (LOQ), precision, accuracy, robustness and ruggedness. Dapagliflozin was eluted at 5.5 ± 0.5 min at wavelength 203 nm. The anticipated technique is linear in the range of 10-50 µg/ml and correlation co-effective (r2) got as 0.9994. The theoretical plates and peak tailing was discovered as 4229 and 1.03 respectively. The percentage accuracy in terms of recovery was accomplished in acceptable range of 98-102. The recently proposed, validated technique is distinct and reproducible for the normal investigation of dapagliflozin in bulk form. Proposed method stability was established by forced degradation studies of drug. In this examination the product was degraded under states of acidic hydrolysis and alkaline hydrolysis, oxidation, photolytic and thermal stress in light of the proposals of International Conference on Hormonization (ICH) Q2R1 Guidelines.

Vanadium (V) forms a yellow coloured water soluble complex with 3-methoxysalcilaldehyde isonicoti... more Vanadium (V) forms a yellow coloured water soluble complex with 3-methoxysalcilaldehyde isonicotinoylhydrazone (MSIH) reagent in acidic buffer pH 4.75 with ëmax at 346 nm. The Molar absorpitivity and Sandell's sensitivity are 8.1 x 10 4 L Mole-1 cm-1 and 0.00629 µg / cm 2 respectively. The Beer's law validity range is 0.051 to 0.51 µg / mL. Vanadium (V) forms (M: L) 1:2 complex with MSIH and stability constant of the complex is 7.7 x 10 15. The developed Second derivative Spectrophotomrtic method was employed for the determination of Vanadium (V) in alloy samples. The effect of various diverse ions also studied.

A new simple stability indicating and user friendly RP-Liquid Chromatographic method was develope... more A new simple stability indicating and user friendly RP-Liquid Chromatographic method was developed for the accurate and precise determination of Valganciclovir using Phenomenex Gemini-NX C18 Column (250 mm Length × 4.6 mm diameter × 5 μm particle size) and variable wavelength (UV) detector. The mobile phase used for the study was sodium Citrate buffer:Methanol in a ratio of 40:60 v/v with a flow rate of 1.0 ml/min. Valganciclovir was detected at wavelength 254 nm and eluted at 2.18 ± 0.5 min. The developed method is linear over 10-80 µg/ml concentration range and correlation coefficient (r 2) obtained as 0.9996. The tailing factor and plate count was found 1.32 and 3649 respectively. The proposed method was proven as robust after its extensive validation, which involves various parameters such as Precision, Linearity, Accuracy, Ruggedness, Robustness, Limit of Detection (LOD), Limit of Quantification (LOQ) and specificity. The developed and validated method is definite and reproducible, can be used for routine analysis of Valganciclovir in bulk form.

A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for ... more A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for the accurate determination of Valacyclovir using GracesmartRP18, C18 Column (250 mm × 4.6 mm, 5 μm particle size). The mobile phase used for the determination was Methanol: Citric Acid buffer in a ratio of 60: 40 v/v at a flow rate of 1.0 mL per min. Valacyclovir was eluted at 2.2 ± 0.1 min and detected at 254 nm. The method is linear over the concentration range of 10-50 µg/mL with correlation coefficient r 2 = 0.999. The plate count and tailing factor was found 3847 and 1.24 respectively. The developed method was proved to be robust after extensively validated with different parameters such as Linearity, Precision, Accuracy, Robustness, Ruggedness, Limit of Detection (LOD), Limit of Quantification (LOQ) and specificity. The validated method is definite, meticulous and reproducible and can be used for routine analysis of Valacyclovir in bulk form.

A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for ... more A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for the accurate determination of Canagliflozin using Phenomenex Gemini-NX C18 Column (250×4.6 mm, 5 μm particle size). The mobile phase used for the determination was Acetonitrile: 1-octanesulphonic acid in a ratio of 70:30 v/v at a flow rate of 1 mL per min. Canagliflozin was eluted at 3.4 ± 0.5 min and detected at 245 nm. The method is linear over the concentration range of 10-100 µg/mL with correlation coefficient r = 0.9997. The plate count and tailing factor was found 5398 and 1.05 respectively. The developed method was extensively validated with different parameters such as Linearity, Precision, Accuracy, Robustness, Ruggedness, Limit of Detection (LOD) and Limit of Quantification (LOQ) and proved to be robust. The validated method is definite, meticulous and reproducible and can be used for routine analysis of Canagliflozin in bulk form. KEY WORDS: Canagliflozin, C18 Column, Acetonitrile: 1-octanesulphonic acid (70:30%), UV detector 245 nm.

Methanol and acetone extracts from leaf and root of Cardiospermum halicacabum Linn were investiga... more Methanol and acetone extracts from leaf and root of Cardiospermum halicacabum Linn were investigated for in-vitro anti-bacterial property by agar disc diffusion method. The crude extracts in acetone and methanol of Cardio-spermum halicacabum Linn root exhibited good anti-microbial activity against the Salmonella typhi and Proteusm irabilis. Leaf extract in methanol exhibited good anti-microbial activity against the Proteusm irabilis. Leaf extract in acetone exhibited moderate inhibition activity against the Staphylococcus aureus.

A simple and derivative spectrophotometric method has been developed for the determination of pal... more A simple and derivative spectrophotometric method has been developed for the determination of palladium (II) using cinnamaldehyde isonicotinoyl hydrazone (CINH) reagent in aqueous medium. Palladium (II) forms a yellow colored water soluble complex with the CINH reagent in acidic buffer range of pH 3.0-6.0. Beer's law obeyed in the range 0.106 to 2.128 μg mL-1 of Pd (II) λ max at 412 nm. The molar absorptivity and Sandell's sensitivity of colored species are 1.03 x 10 4 L.mol-1 cm-1 and 0.0054µg cm-2 respectively. Palladium (II) forms (M: L) 1:1 complex and stability constant of the complex is 9.3 x 10 4. The developed derivative spectrophotometric methods were employed for the determination of palladium (II) in alloy samples and hydrogenation catalyst samples.

A rapid and nondestructive method for the determination of trace level moisture content in Ethyla... more A rapid and nondestructive method for the determination of trace level moisture content in Ethylacetate using Fourier transform near infrared (FT-NIR) Spectroscopy was developed and validated. Partial least squares regression (PLSR) was applied to develop a calibration model. The method is linear, precise, robust and accurate in the range of 0.02% to 3.5% of moisture content. The square of correlation coefficient and Root Mean square error of cross validation (RMSECV) is obtained as 99.9 and 0.01 respectively. The developed method was employed for the determination of moisture content in recovered and fresh Ethylacetate samples.

Journal of Applicable Chemistry, 201 3 , 2 ( 6 ): 1489 - 1498, Oct 29, 2013

Therapeutic eminence of the hydrazide - hydrazone derivatives has been well recognized, in additi... more Therapeutic eminence of the hydrazide - hydrazone derivatives has been well recognized, in addition, hydrazide - hydrazones were reported to bring forth anticancer, anti- HIV properties and hence they have gained an imperative place in medicinal chemistry. Encouraged by these observations and in continuatio
n of our research on novel hydrazone derivatives derived from 2,5-
Difluorobenzoic acid, we intended to synthesize a series of new hydrazide derivatives with the aim of attaining promising
antimicrobial compounds to improve actual antimicrobial treatments

Chem. Met. Alloys 5 (2012)

A sensitive spectrophotometric method has been developed for the determination of ruthenium(III) ... more A sensitive spectrophotometric method has been developed for the determination of ruthenium(III) using 3,5 dimethoxy 4 hydroxybenzaldehyde isonicotinoylhydrazone (DMHBIH) in presence of neutral micellar medium of Triton X 100. The metal ion forms a brownish yellow colored water soluble complex with the DMHBIH reagent in acidic buffer pH 4.25. Spectral data shows the formation of an 1:1 (M:L) complex with a stability constant 1.82 × 106. Beer’s law is obeyed over a concentration range of 0.202 to 4.043 μg/mL of Ru(III) at 390 nm. The molar absorptivity and Sandell’s sensitivity are calculated to be 1.7 × 104 L.mol 1.cm 1 and 0.006 μg.cm 2 Ru(III) respectively. The developed derivative spectrophotometric method was employed for the determination of Ru(III) in synthetic alloy samples and real water samples. The effect of various diverse ions has also been studied.

A simple and sensitive spectrophotometric method has been developed for the determination of pall... more A simple and sensitive spectrophotometric method has been developed for the determination of palladium(II) using newly synthesized 3-methoxysalcilaldehyde-4-hydroxybenzoylhydrazone (MSHBH) reagent in a micellar medium of CTAB (acidic surfactant). Palladium(II) forms an orange yellow colored water soluble complex with the MSHBH reagent in acidic buffer medium pH 4.5. Beer’s law obeyed in the range 0.2876 to 4.2568 μg/mL of Pd(II) λmax at 412 nm. The molar absorptivity and Sandell’s sensitivity of colored species are 1.03 x104 L.mol-1.cm-1 and 0.0103 µg.cm-2 respectively. Palladium(II) forms (M: L) 1:1 complex and stability constant of the complex is 9.32x104. The developed first and second order derivative spectrophotometric methods were employed for the determination of palladium(II) in alloy samples and hydrogenation catalyst samples.

"ABSTRACT A simple and sensitive spectrophotometric method has been developed for determinatio... more "ABSTRACT

A simple and sensitive spectrophotometric method has been developed for determination of thorium (IV) using newly synthesized 3-methoxysalcilaldehyde-4-hydroxybenzoylhydrazone (MSHBH) reagent in a micellar medium of Triton X -100 (neutral surfactant). Thorium (IV) forms a yellow coloured water soluble complex with the reagent in acidic buffer medium pH 4.25. Beer’s law obeyed in the range 0.232 to 4.641 μg/ml of Th (IV) λmax at 394 nm. The molar absorptivity and Sandell’s sensitivity of coloured species are 2.0 x 104 l.mol-1.cm-1 and 0.012 μg/cm2 respectively. Thorium (IV) forms (M: L) 1:1 complex and stability constant of the complex is 1.95 x 105. The developed derivative spectrophotometric method was employed for the determination of thorium (IV) in monazite sand. "

Archives of Applied …, Jan 1, 2011

Conference Presentations by Dr. Rameswara Rao Modalavalasa

A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for ... more A simple reverse phase liquid chromatographic method with ultraviolet detector was developed for the accurate determination of Canagliflozin using Phenomenex Gemini-NX C18 Column (250×4.6 mm, 5 μm particle size). The mobile phase used for the determination was Acetonitrile: 1-octanesulphonic acid in a ratio of 70:30 v/v at a flow rate of 1 mL per min. Canagliflozin was eluted at 3.4 ± 0.5 min and detected at 245 nm. The method is linear over the concentration range of 10-100 µg/mL with correlation coefficient r = 0.9997. The plate count and tailing factor was found 5398 and 1.05 respectively. The developed method was extensively validated with different parameters such as Linearity, Precision, Accuracy, Robustness, Ruggedness, Limit of Detection (LOD) and Limit of Quantification (LOQ) and proved to be robust. The validated method is definite, meticulous and reproducible and can be used for routine analysis of Canagliflozin in bulk form. KEY WORDS: Canagliflozin, C18 Column, Acetonitrile: 1-octanesulphonic acid (70:30%), UV detector 245 nm.

Journal of Applicable Chemistry, 201 3 , 2 ( 6 ): 1489 - 1498, Oct 29, 2013

Chem. Met. Alloys 5 (2012)

"ABSTRACT A simple and sensitive spectrophotometric method has been developed for determinatio... more "ABSTRACT

Archives of Applied …, Jan 1, 2011

ABSTRACT Organic compounds containing different functional groups have been used as chromogenic ... more ABSTRACT
Organic compounds containing different functional groups have been used as chromogenic reagents in the trace metal analysis. Survey of literature reveals that, the hydrazones are potential analytical reagents for the spectrophotometric determination of metal ions. In view of the above the author interested to synthesize new hydrazones viz. 3-methoxysalcilaldehyde-4-hydroxybenzoylhydrazone (MSHBH), 3,5-dimethoxy-4-hydroxybenzaldehydeisonicotinoyl hydrazone (DMHBIH), 2-hydroxy-3-methoxy benzaldehyde isonicotinoylhydrazone (HMBIH). The structure of the above ligands was confirmed by IR, NMR, mass and UV-Visible spectral data.
Spectrophotometry, a widely employed analytical technique is more popular because of the common availability of instrumentation and simple procedures as well as speed, precision and accuracy resulting in extensive literature being published every year.
All the above reagents forms water soluble complexes with palladium(II), thorium(IV), molybdenum(VI), ruthenium(III) and uranium(VI). The systematic study of the above metal ions was carried out and incorporated in this thesis.
The thesis consists of nine chapters; Chapter-1 describes the introduction, review of past work, objectives and importance of the present investigations.
Chapter -2 describes preparation of solutions, purification of solvents, solutions of various ions, a brief description of instruments employed in the present study and general experimental procedures of the investigation.
Chapter-3 contains synthesis and characterization of new organic reagents.
Chapter -4 deals with direct, first and second order derivative spectrophotometric determination of palladium(II), thorium(IV) and molybdenum(VI) using MSHBH reagent in presence of surfactant.
Chapter-5 describes the direct and derivative spectrophotometric determination of platinum group metals such as ruthenium(III) and palladium(II) using DMHBIH reagent in presence of Triton X-100.
Chapter-6 deals with direct, first and second order derivative spectrophotometric determination of uranium(VI) (radioactive element) using HMBIH reagent.
Chapter-7 describes the simultaneous determination of copper(II), nickel(II) and copper(II), cobalt(II) using MSHBH reagent in presence of micellar medium.
Chapter-8, 9 deals with the summary and conclusions of the present investigations.

Chemistry of Metals and Alloys, 2011

A simple and sensitive spectrophotometric method has been developed for the determination of gold... more A simple and sensitive spectrophotometric method has been developed for the determination of gold(III) using the newly synthesized reagent 3,5-dimethoxy-4-hydroxybenzaldehyde isonicotinoyl hydrazone (DMHBIH) in a neutral surfactant of Triton X-100 (5 %) (micellar medium). Gold(III) forms an orange coloured water soluble complex with the reagent in acidic medium pH 4.0. The molar absorptivity and Sandell's sensitivity of the coloured species are 1.14×10 5 l mol-1 cm-1 and 0.004587 µg/cm 2 , respectively. Beer's law is obeyed in the range 0.197-1.97 µg/ml of Au(III) at λ λ λ λ max at 386 nm. The developed derivative spectrophotometric method was satisfactorily applied for the determination of gold(III) in synthetic mixtures, certified reference materials, water samples and pharmaceutical samples.

Analytica Chimica Acta, 1990

Abstract A modified method for the determination of sulphonamides, based on the Bratton-Marshall ... more Abstract A modified method for the determination of sulphonamides, based on the Bratton-Marshall reaction with derivative spectrophotometry, is proposed. Diverse sulphonamides are determined with excellent precision by using first- to fourth-order derivative spectra. The method was applied for the determination of sulphonamides in urine, honey and pharmaceutical formulations without pretreatment of the samples.

A simple and sensitive spectrophotometric method has been developed for the determination of pall... more A simple and sensitive spectrophotometric method has been developed for the determination of palladium(II) using newly synthesized 3-methoxysalcilaldehyde-4-hydroxybenzoylhydrazone (MSHBH) reagent in a micellar medium of CTAB (acidic surfactant). Palladium(II) forms an orange yellow colored water soluble complex with the MSHBH reagent in acidic buffer medium pH 4.5. Beerâs law obeyed in the range 0.2876 to 4.2568 I¼g/mL of Pd(II) I»max at 412 nm. The molar absorptivity and Sandellâs sensitivity of colored species are 1.03 x104 L.mol-1.cm-1 and 0.0103 I¼g.cm-2 respectively. Palladium(II) forms (M: L) 1:1 complex and stability constant of the complex is 9.32x104. The developed first and second order derivative spectrophotometric methods were employed for the determination of palladium(II) in alloy samples and hydrogenation catalyst samples.

International Journal of Research in Pharmaceutical Sciences, 2016

Methanol and acetone extracts from leaf and root of Cardiospermum halicacabum Linn were investiga... more Methanol and acetone extracts from leaf and root of Cardiospermum halicacabum Linn were investigated for in-vitro anti-bacterial property by agar disc diffusion method. The crude extracts in acetone and methanol of Cardiospermum halicacabum Linn root exhibited good anti-microbial activity against the Salmonella typhi and Proteusm irabilis. Leaf extract in methanol exhibited good anti-microbial activity against the Proteusm irabilis. Leaf extract in acetone exhibited moderate inhibition activity against the Staphylococcus aureus. Keywords: Anti-microbial activities, Cardiospermum halicacabum Linn, acetone, methanol.

Chemistry of Metals and Alloys, 2012

A sensitive spectrophotometric method has been developed for the determination of ruthenium(III) ... more A sensitive spectrophotometric method has been developed for the determination of ruthenium(III) using 3,5-dimethoxy-4-hydroxybenzaldehyde isonicotinoylhydrazone (DMHBIH) in presence of neutral miceller medium of Triton X-100. The metal ion forms a brownish yellow coloured water soluble complex with the DMHBIH reagent in acidic buffer pH 4.25. Spectral data shows the formation of an 1:1 (M:L) complex with a stability constant 1.82 × 10 6. Beer's law is obeyed over a concentration range of 0.202 to 4.043 µg/mL of Ru(III) at 390 nm. The molar absorptivity and Sandell's sensitivity are calculated to be 1.7 × 10 4 L.mol-1 .cm-1 and 0.006 µg.cm-2 Ru(III) respectively. The developed derivative spectrophotometric method was employed for the determination of Ru(III) in synthetic alloy samples and real water samples. The effect of various diverse ions has also been studied. Derivative spectrophotometry / Ruthenium(III) / 3,5-dimethoxy-4-hydroxybenzaldehyde isonicotinoylhydrazone (DMHBIH) / Synthetic alloy samples / Real water samples

A new simple stability indicating and user friendly RP-Liquid Chromatographic method was develope... more A new simple stability indicating and user friendly RP-Liquid Chromatographic method was developed for the accurate and precise determination of Valganciclovir using Phenomenex Gemini-NX C18 Column (250 mm Length × 4.6 mm diameter × 5 μm particle size) and variable wavelength (UV) detector. The mobile phase used for the study was sodium Citrate buffer:Methanol in a ratio of 40:60 v/v with a flow rate of 1.0 ml/min. Valganciclovir was detected at wavelength 254 nm and eluted at 2.18 ± 0.5 min. The developed method is linear over 10-80 μg/ml concentration range and correlation co-efficient (r2) obtained as 0.9996. The tailing factor and plate count was found 1.32 and 3649 respectively. The proposed method was proven as robust after its extensive validation, which involves various parameters such as Precision, Linearity, Accuracy, Ruggedness, Robustness, Limit of Detection (LOD), Limit of Quantification (LOQ) and specificity. The developed and validated method is definite and reproduci...