Development and validation of zero and first-order derivative area under curve spectrophotometric methods for the determination of entacapone in bulk material and in tablets.

AIM: The aim of this work is to establish two simple, economical, and rapid spectrophotometric methods for the quantification of entacapone in bulk material and in tablets. Further, this study is designed to validate the developed methods as per ICH guidelines. MATERIALS AND METHODS: In Methods I and II, a stock standard solution was prepared by dissolving 10 mg of entacapone in 100 mL of 10% v/v acetonitrile to obtain a concentration of 100 µg/mL. After suitable dilution, 10 µg/mL of entacapone was prepared and scanned in the UV-visible range 500-200 nm; entacapone showed a maximum absorbance at 384.40 nm. In Method I, area under curve (AUC) of the zero-order spectrum was recorded between 348.00 and 410.20 nm. While, in Method II, zero-order spectra were derivatized into first-order, and the AUC was recorded between 386.40 and 460.20 nm. For a linearity study, series of dilutions were prepared from stock solutions. RESULTS: In Method I, and II, entacapone followed linearity in the concentration range of 2-12 µg/mL and 5-30 µg/mL with (r(2)>0.999). The amounts of entacapone estimated by both these methods were found to be 99.24 ± 0.054 and 98.68 ± 1.04, respectively. CONCLUSION: The developed methods are simple, precise, rugged, robust, and economical. Both these methods can be used for routine analysis of entacapone from its tablet formulation.

Quantitative determination of levofloxacin hemihydrate in bulk and tablets by UV-spectrophotometry and first order derivative methods.

Two simple, rapid, accurate and economical 'UV Spectrophotometry' and 'First Order Derivative' methods have been developed for determination of levofloxacin hemihydrate in bulk and tablets. In (10% v/v) acetonitrile, the lambdamax of the drug was found to be 288 nm. The same spectrum was derivatised into first order derivative, using UV probe software of instrument (Shimadzu-2450), at Deltalambda=4. The amplitude of the trough was recorded at 297 nm. In both the proposed methods, levofloxacin hemihydrate follows linearity in the concentration range 2-12 microg/ml with a correlation coefficient of 0.9999. Assay results were in good agreement with label claim. The methods were validated statistically and by recovery studies. The relative standard deviation were found to be less than 2% with excellent precision and accuracy.

Validated HPTLC method for simultaneous estimation of levofloxacin hemihydrate and ornidazole in pharmaceutical dosage form.

A simple, rapid, and accurate high-performance thin-layer chromatography (HPTLC) method is described for the simultaneous determination of levofloxacin hemihydrate and ornidazole in tablet dosage form. The method is based on the HPTLC separation of the two drugs followed by densitometric measurements of their spots at 298 nm. The separation is carried out on Merck TLC aluminium sheets of silica gel 60 F254 using n-butanol-methanol-ammonia (5:1:1.5, v/v/v) as mobile phase. The linearity is found to be in the range of 50-250 and 100-500 ng/spot for levofloxacin hemihydrate and ornidazole, respectively. The method is successively applied to pharmaceutical formulation because no chromatographic interferences from the tablet excipients are found. The suitability of this HPTLC method for the quantitative determination of the compounds is proved by validation in accordance with the requirements laid down by International Conference on Harmonization (ICH) guidelines.