Development of continuously operated aqueous two-phase microextraction process using natural deep eutectic solvents

Abstract In this work, fast continuously operated microextraction of polyphenolic compounds using ATPSs formed form NADESs and potassium hydrogen phosphate was developed. The effects of the NADES mass, extraction time, extraction temperature, salt concentration and gallic acid concentration on the extraction efficiency have been investigated in batch experiments. Furthermore, a 2D model considering convection in the flow direction and diffusion in two directions at steady-state conditions was developed and the developed extraction method was verified using two realistic samples (aqueous extracts of lemon balm and mint). Using a continuous microextractor, an extraction efficiency of approximately 94% was achieved for a residence time of τ = 3.65 s, which is a significant improvement compared to the batch process where an extraction efficiency of 88% was achieved for a residence time of t = 15 min. Also, the proposed 2D mathematical model described the extraction in a continuously operated micro extractor with high accuracy.