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.

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%.

Development of a chemometric-assisted deep eutectic solvent-based microextraction procedure for extraction of caffeine in foods and beverages.

In this research article, a novel and green deep eutectic solvent-based microextraction (DES-ME) procedure based on chemometric-assisted (CA) optimization was developed for the extraction of caffeine in foods and beverages prior to its spectrophotometric determination. Ultrasound was used to accelerate the extraction of caffeine. Deep eutectic solvents (DES), prepared in an ultrasonic bath at 20-60 min for 60-80°C, were used as extraction solvents. The important experimental variables (pH, DES amount, temperature, sonication time and metal concentration) were modelled and optimized using response surface methodology (RSM) based on central composite design (CCD). Under the optimum conditions, the proposed method allowed the determination of caffeine with limits of detection (LOD, 3sblank/m) and quantification (LOQ, 3sblank/m) of 7.5 and 25.0 µg L-1, respectively. For 40 µg L-1 and 100 µg L-1 of caffeine (n = 5), relative standard deviations (RSDs%) and recoveries% were 1.2-1.6% and 96.7-98.2%, respectively. Validation studies (accuracy, precision, trueness, reliability and selectivity) of the method were performed before the analysis of real samples. The results showed that the combination of the CCD with the DES-ME can be considered as a new perspective for the extraction and determination of caffeine in foods and beverages.