Towards green analysis of curcumin from tea, honey and spices: Extraction by deep eutectic solvent assisted emulsification liquid-liquid microextraction method based on response surface design

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A fast, cheap and green analytical method was developed for the determination and extraction of curcumin in tea, honey, and spices using deep eutectic solvent-assisted emulsification liquid–liquid micro-extraction (DES-ELLME) coupled to UV-VIS spectrophotometry. Quantitative extraction of curcumin from the sample was obtained by the DES, which was prepared by mixing choline chloride and maltose in a 1:3 molar ratio. Response surface design was used for the optimisation of significant experimental parameters including sample pH, amount of extraction solvent, amount of emulsifier solvent and vortex time. The optimum conditions obtained were pH 4.25, 762.5 μL of DES, 107.5 mL of tetrahydrofuran and 3.4 min vortex time, while keeping centrifugation speed fixed at 4000 rpm, 5 min. Under the extraction conditions obtained, analytical features such as calibration equation, limit of detection, enrichment factor, and linearity were Abs = 6.5 × 10−4 [Curcumin, ng mL−1]-1.2 × 10−5, 0.1 ng mL−1, 114 and 0.4–120 ng mL−1, respectively. Moreover, the repeatability and reproducibility of the DES-ELLME method, expressed as relative standard deviation (RSDs%), varied in the ranges of 1.4–3.0% and 2.0–4.3%, respectively. Finally, the proposed method was successfully applied to the extraction and determination of curcumin from prepared samples. The relative mean recovery ranged from 92.3% to 104.4%.