Stability-indicating TLC—image analysis method for determination of andrographolide in bulk drug and Andrographis paniculata formulations

Abstract

A simple and rapid thin-layer chromatographic (TLC)–image analysis method was developed for stability-indicating studies and determination of andrographolide in bulk drug and in Andrographis paniculata formulations. Good chromatographic separation of andrographolide and the degradation products under various stress conditions was achieved on a silica gel G60 F254 TLC plate with the use of two mobile phases, dichloromethane—toluene—ethanol (6:3:1, v/v/v) and toluene—ethyl acetate—formic acid (5:3.5:1.5, v/v/v) and p-anisaldehyde as visualization reagent. Image analysis of the scanned TLC plate was performed by Sorbfil TLC Videodensitometer, UN-SCAN-IT, JustTLC, and ImageJ software to measure the quantity of the dark bluecolored band of andrographolide on a TLC plate. The TLC—image analysis method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, and robustness and was also applied for determination of the amount of andrographolide in A. paniculata formulations and the content of andrographolide remained in the samples under forced degradations. The analytical results determined by the TLC—image analysis method, TLC—densitometry, and high-performance liquid chromatography (HPLC) methods were compared and found to be not significantly different.