An HPTLC method was developed and validated for simultaneous determination of stevioside (STE) and rebaudioside-A (REB-A) in Stevia rebaudiana leaves. The HPTLC separation was performed on precoated silica gel 60F254 HPTLC plates with the mobile phase ethyl acetate-ethanol-acetone-water (15 + 3 + 6 + 6, v/v/v/v). The densitometric quantification of steviol glycosides was carried out at Amax 580 nm in the reflection-absorption mode after spraying with anisaldehyde-sulfuric acid reagent. Rf values were 0.34 and 0.28 for STE and REB-A, respectively. The content of STE and REB-A in leaf extract was found to be 6.94 and 6.35%, respectively. The method was validated in terms of precision, accuracy, specificity, and robustness. The method can be useful for routine analysis of the sweeteners.
A sensitive and reproducible HPLC method has been developed for quantitative analysis of telmisartan. The drug was separated from its degradation products on a C 18 column at ambient temperature with methanol-water 80:20 (v/v), pH 4.0 (adjusted by addition of orthophosphoric acid), as mobile phase at a flow rate of 1.0 mL min −1 . Under these conditions the retention time of telmisartan was 4.85 ± 0.05 min. Quantification on the basis of peak area was achieved by UV detection at 225 nm; calibration plots were linear in the concentration range 10-60 μg mL −1 . When the method was applied to a pharmaceutical formulation there was no chromatographic interference from tablet excipients. The method was validated for precision, robustness, recovery, and limits of detection and quantification. The drug was subjected to acidic and alkaline hydrolysis, and oxidising, dry heat, wet heat, and photodegrading conditions. Because the method could effectively separate the drug from its degradation products, it can be regarded as stability indicating.
A simple, specific, accurate and stability-indicating reversed phase high performance liquid chromatographic method was developed for the simultaneous determination of mephenesin and diclofenac diethylamine, using a Spheri-5-RP-18 column and a mobile phase composed of methanol: water (70:30, v/v), pH 3.0 adjusted with o-phosphoric acid. The retention times of mephenesin and diclofenac diethylamine were found to be 3.9 min and 14.5 min, respectively. Linearity was established for mephenesin and diclofenac diethylamine in the range of 50-300 μg/ml and 10-60 μg/ml, respectively. The percentage recoveries of mephenesin and diclofenac diethylamine were found to be in the range of 99.06-100.60% and 98.95-99.98%, respectively. Both the drugs were subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, photolytic and UV degradation. The degradation studies indicated, mephenesin to be susceptible to neutral hydrolysis, while diclofenac diethylamine showed degradation in acid, H2O2, photolytic and in presence of UV radiation. The degradation products of diclofenac diethylamine in acidic and photolytic conditions were well resolved from the pure drug with significant differences in their retention time values. This method can be successfully employed for simultaneous quantitative analysis of mephenesin and diclofenac diethylamine in bulk drugs and formulations.
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