Development and Validation of a Stability-Indicating HPTLC Method for the Analysis of Gentamicin Sulphate in Pharmaceutical Ointments

This study developed and validated a stability-indicating high-performance thin-layer chromatography (HPTLC) method for the identification and quantification of gentamicin sulphate in an ointment formulation using silica gel 60 F254 HPTLC plates as the stationary phase and methanol: chloroform: ammonia solution (25%) (1:1:1, v/v/v) as the mobile phase. An ideal solvent ratio, chloroform: methanol (9:1, v/v), was used to dissolve the ointment sample before analysis. According to the guidelines of the International Council for Harmonisation (ICH), the HPTLC method was validated, demonstrating specificity by separating all three bands of gentamicin sulphate without interference from ointment excipients and/or degradation products resulting from photolytic, photolytic and oxidative, oxidative, acidic, and alkaline stress conditions. The findings of the study also revealed that the method has high levels of linearity within the range of 50–300 ng/band (R2 ≥ 0.99), with detection and quantification limits of 7.10 ng, and 21.53 ng, respectively. Additionally, the method does not require any sample pre-treatment, such as extraction from the ointment base, making it simple and convenient for the quality control of gentamicin ointments.