TLC- smartphone for ofloxacin and dexamethasone determination in pharmaceutical formulation and rabbit aqueous humor

Preserving the environment and reducing the harmful effects of chemicals on it, is a primary goal of the research, nowadays. One of the major challenges for research is assessing the efficiency and quality of the proposed method in terms of environmental and human safety, as well as their overall cost. Thin layer chromatography (TLC)-Smartphone is a simple, cost-effective, and rapid method for the detection and quantification of analytes. This work describes the development of a green, white, sensitive and easy TLC method that employs a smartphone charge-coupled device (CCD) camera for image acquisition that provides data regarding the identity and quantity of ofloxacin (OFL) and dexamethasone (DEXA) in their mixture. A mixture of OFL and DEXA was separated on a silica gel 60 F₂₅₄ plate using a mobile phase of n-butanol: acetic acid: water (6:2:2, by volume). Visualization of the separated spots was achieved using the "Universal Stain" iodine vapor (I₂) and potassium permanganate (KMnO₄), resulting in colored spots on the TLC plate. The R_f values of ofloxacin (0.25) and dexamethasone (0.8) were determined from the recorded images, enabling the identification of the drugs. It was possible to construct a linear calibration model and relate optical density with concentration per band. A linear calibration model was constructed to correlate optical density with concentration per band. A smartphone application was developed to calculate the spot intensity, which was then used to quantify ofloxacin and dexamethasone in their mixture. The TLC-Smartphone method produced linear calibration curves between the color intensity of each spot and the corresponding concentrations. For iodine vapor visualization, the linearity range was 10-50 μg/band for ofloxacin and 40-120 μg/band for dexamethasone. For KMnO₄ visualization, the linearity was in the range of 10-50 μg/band for both drugs. The proposed method was validated following ICH guidelines, and was successfully applied for the estimation of ofloxacin and dexamethasone in their eye drop pharmaceutical form and rabbit aqueous humor.