STABILITY INDICATING ASSAY AND KINETIC STUDY FOR NORFLOXACIN USING TLC-DENSITOMETRIC METHOD

Abstract

A new, simple, and stability indicating thin layer chromatographic (TLC) method has been developed for estimation of norfloxacin. Study was performed on precoated silica gel F₂₅₄ TLC plate using environmentally safe mobile phase consisting of n-butanol:methanol:ammonia (33%) (8:1:3.5 v/v). A Camag TLC Scanner 3 set at 282 nm was used for direct determination of the chromatograms in the reflectance/absorbance mode. Method was validated according to ICH guidelines. Determination coefficient of the calibration curve was 0.9962 in the range 6–150 ng/band with limit of detection and limit of quantification of 1.01 ng/band and 3.06 ng/band, respectively. Statistical comparison of the results with those of the official HPLC method showed good agreement between the official and the proposed methods with respect to accuracy and precision. Norfloxacin was subjected to forced degradation at 150°C with 2 M HCl or 2 M NaOH, and the degradation rate in both cases was studied. The calculated first order rate constant for the degradation were determined at 0.056 and 0.023 hour⁻¹ and the t_1/2 were 12.28 and 30.09 hr for acid and base degradation, respectively. The method has the potential to determine norfloxacin in different dosage forms and in quality control laboratories.

Keywords:

• densitometry
• kinetic study
• method validation
• norfloxacin
• stability indicating assay
• standard addition method

ACKNOWLEDGMENT

The authors are very grateful to the staff of the Pharmaceutical Services Center, Faculty of Pharmacy, Assuit University for providing the laboratories facilities and for their helpfulness. The authors are indebted to the Egyptian International Pharmaceutical Industries Co., E.I.P.I.CO. for providing the gift of authentic norfloxacin.

Notes

^a Tailed spot.

^a (n = 3).

^a Avearge of six determinations.

^a Average of three determinations.

^b Following the general assay procedure conditions.

^a Average of three determinations.

^a Average of three determinations.

^b Ref. [2] Theoretical value for t and F at 95% confidence limit, t = 2.776 and F = 19.

*Authentic drug added (30, 60, and 90 ng or 100, 200, and 300% of the claimed sample amount).