A green method for determination of ethanol in homeopathic medicines using thermal infrared enthalpimetry

In this work, a simple and fast method is proposed for the determination of ethanol in homeopathic medicines using thermal infrared enthalpimetry (TIE). Samples containing alcohol in a wide concentration range (from 5% to 95% v/v) were used. Purified water or absolute ethanol was added directly into homeopathic medicine and increase of temperature was monitored using an infrared camera. Total volume, stirring speed and dispensing rate of solutions were the most significant parameters studied for method optimization. A response surface methodology (RSM) was used for optimization of the experimental conditions. The method was validated in the following parameters: selectivity, linearity, linear range, precision (repeatability and intermediate precision), limit of detection and quantification, accuracy and robustness. Linear range was obtained from 4% to 55% (ethanol, v/v). The proposed method showed accuracy in agreement with the conventional one. The proposed method it was demonstrated a good alternative for determination of ethanol in homeopathic medicines, presenting low cost, fast analysis and agreement with the principles of green analytical chemistry.