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combustion occurs constituting a measure of an inorganic content [ 3 ]. In the case of composites filled with 1.5 and 5 mass% the thermal degradation temperature increases in comparison with pure PE. The most significant increase in decomposition temperatures

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Poly (chloromethyl- p -styrene) (chlorometylated PS): compound 7 Thermal degradation of chloromethylated PS ( 7 ), used as reference, occurs in two stages, which is in accordance to other data published by Zhao et al. [ 21 ]. These authors

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degradation) and light (photo degradation) was studied on solid state. In case of thermal degradation, the drug powder contained in sealed glass ampoule was heated in an oven at 60 °C/80 °C/100 °C/200 °C for a period of 8 days. Control sample was maintained in

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as pyrolysis. Thermal degradation of agricultural biomasses The TG and DTG curves of sunflower shell, eucalyptus, wheat straw and peanut shell biomasses samples at a heating rate of 10 °C/min are

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Summary

A stability-indicating LC assay method was developed and validated for the quantitative determination of doripenem and biapenem in pharmaceutical dosage forms in the presence of degradation products formed during forced degradation studies. An isocratic RP-HPLC method was developed with a C-18 (250 mm × 4.6 mm, 5 μm) column and 12 mM ammonium acetate-acetonitrile (96:4 υ/υ) as mobile phase. The flow rate of the mobile phase was 1.0 mL min−1 for doripenem and biapenem. The determination was carried out at the wavelength of 295 nm. The carbapenems were subjected to stress conditions of degradation in aqueous solutions including hydrolysis, oxidation, photolysis, and thermal degradation. The developed method was validated with respect to linearity, accuracy, precision, selectivity, and robustness.

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A new, sensitive, stability-indicating, and cost and time-effective isocratic reversed-phase UHPLC method has been developed for quantitative analysis of felbamate, an antiepileptic drug, both in the bulk drug and in pharmaceutical dosage forms. Chromatographic separation of felbamate and its two impurities was achieved on a C18 column with a simple buffer-methanol mobile phase; the run time was 8 min. Quantification was achieved by ultraviolet detection. Resolution between the impurities was >2.0. Response was a linear function of concentration over the range 0.1–3.0 μg mL−1, correlation coefficient >0.999, for felbamate and the impurities. The method is capable of detecting the two impurities at levels of 0.002% (0.02 μg mL−1) of the test concentration of 1.0 mg mL−1 (1 μL injection). The same sensitivity was achieved for all the degradation products formed during stress studies in which the drug was subjected to hydrolysis, oxidation, photolysis, and thermal degradation. Substantial degradation occurred under acidic and basic conditions. The stressed test solutions were assayed against felbamate working standard and the mass balance in each case was close to 100%, indicating the method is stability-indicating. The method was validated for linearity, accuracy, precision, and robustness in accordance with ICH Guidelines.

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A novel stability-indicating reversed-phase (RP) HPLC method has been developed and validated for quantitative analysis of eplerenone in the bulk drug and in a pharmaceutical dosage form. Use of a 250 mm × 4.6 mm, 5-μm particle, C18 column with 55:45 (v/v) 50 mM ammonium acetate buffer (pH 7)-acetonitrile as isocratic mobile phase enabled separation of the drug from its degradation products. UV detection was performed at 240 nm. The method was validated for linearity, accuracy (recovery), precision, specificity, and robustness. The linearity of the method was excellent over the range 10–100 μg mL−1 (correlation coefficient 0.999). The limits of detection and quantification were 0.019 and 0.053 μg mL−1, respectively. Recovery of eplerenone from the pharmaceutical dosage form ranged from 100.97 to 101.25%. Eplerenone was subjected to stress conditions (hydrolysis (acid, base), oxidation, photolysis, and thermal degradation) and the stressed samples were analysed by use of the method. Degradation was observed in acid, base, and 30% H2O2. The drug was stable under the other stress conditions investigated. The degradation products were well resolved from main peak. The forced degradation studies prove the stability indicating power of the method.

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A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method for analysis of rupatadine fumarate, both as the bulk drug and in a tablet formulation, has been developed and validated. Aluminium foil TLC plates precoated with silica gel 60F254 were used as stationary phase and toluene-methanol-triethylamine 4:1:0.2 (v/v) as mobile phase. A compact band (R F 0.61 ± 0.02) was obtained for rupatadine fumarate. Densitometric analysis was performed in absorbance mode at 264 nm. Linear regression analysis revealed a good linear relationship (r 2 = 0.9992 ± 0.0001) between peak area and concentration in the range 400–1400 ng band−1. The mean values ± SD of the slope and intercept were 2.5471 ± 0.005 and 1055.2 ± 4.20, respectively. The method was validated for precision, recovery, and robustness. The limits of detection and quantitation were 66.63 and 201.91 ng band−1, respectively. Rupatadine fumarate was subjected to acid and alkaline hydrolysis, oxidation, and photochemical and thermal degradation and underwent degradation under all these conditions. Statistical analysis proved the method enables repeatable, selective, and accurate analysis of the drug. It can be used for identification and quantitative analysis of rupatadine fumarate in the bulk drug and in tablet formulations.

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A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic method for analysis of repaglinide both in a bulk and in pharmaceutical formulation has been developed and validated. The method employed high-performance thin-layer chromatography (HPTLC) aluminum plates precoated with silica gel 60 RP-18 F254 as the stationary phase. The solvent system consisted of chloroform-methanol-ammonia (4.5:0.8:0.05, v/v). The system was found to give compact spot for repaglinide (R F value of 0.55 ± 0.03). Densitometric analysis of repaglinide was carried out in the absorbance mode at 288 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r 2 = 0.998 ± 0.0015 with respect to peak area in the concentration range 600–1600 ng per spot. The mean value ± SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78, with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 22.64 and 68.84 ng per spot, respectively. Repaglinide was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions. This indicates that the drug is susceptible to acid and base. The degraded product was well resolved from the pure drug with significantly different R F value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of investigated drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of repaglinide in bulk drug and pharmaceutical formulation.

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A simple, selective, precise, and stability-indicating high-performance thinlayer chromatography (HPTLC) method for the analysis of ciprofibrate both in bulk drug and pharmaceutical formulation has been developed and validated. The method employed HPTLC aluminum plates precoated with silica gel 60 RP-18 F254 as the stationary phase. The solvent system consisted of methanol-water-triethylamine (2.8:2.2:0.2 υ/υ). The system was found to give compact spot for ciprofibrate (R F value of 0.55 ± 0.02). Densitometric analysis of ciprofibrate was carried out in the absorbance mode at 232 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r 2 = 0.998 ± 0.0015 with respect to peak area in the concentration range 600–1600 ng per spot. The mean values ± SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78, respectively, with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 17.84 and 54.08 ng per spot, respectively. Ciprofibrate was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions. This indicates that the drug is susceptible to acid and base. The degraded product was well resolved from the pure drug with significantly different R F value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of investigated drug. The proposed developed HPTLC method can be applied for the identification and quantitative determination of ciprofibrate in bulk drug and pharmaceutical formulation.

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