Solid-Phase Fluorimetric Determination of Some Nonsteroidal Anti-Inflammatory Drugs in Medicines with the Aid of a Smartphone

A fast and simple method for determining the active ingredients of non-steroidal anti-inflammatory drugs (NSAIDs) meloxicam and tolfenamic, mefenamic, and niflumic acids using digital colorimetry of solid-state fluorescence was developed. The fluorescence of europium and terbium sensitized by the NSAIDs on cellulose paper and in a thin layer of silica gel was studied. Spots of NSAID solutions applied to the matrix exhibited green fluorescence for tolfenamic, mefenamic, and niflumic acids and red fluorescence for meloxicam upon exposure to UV light (365 nm). The fluorescence intensity on the matrix surface was measured using a smartphone. The colorimetric parameters in the RGB system were used as the analytical signal ( A r ). The limits of detection and quantitation were 1 – 5 and 3 – 17 μg/mL, respectively, for all considered analytes. The range of determined concentrations was 3 – 500 μg/mL. The proposed method was tested on medicinal products. The relative standard deviation of the analytical results was ≤0.08.