Synthesis Of Deep Eutectic Solvent And Its Application In Food And Medicine Analysis

Bioactive compounds that are beneficial to human health,such as phenols,alkaloids,terpenes,polysaccharides,lipids,etc.Its have caused extensive researches.These active substances usually require long-term extraction with organic solvents.Deep eutectic solvent(DES)has become a green alternative solvent because its low volatility,high stability,good solubility,and tailor-made properties.DES is widely used in solid-liquid extraction and liquid-liquid extraction,with simplicity and efficiency.High,green,safe and gentle characteristics.In this thesis,four sample preparation methods of solid-liquid microextraction and liquid-liquid microextraction based on DES have been developed and combined with HPLC,which were applied to detect the tanshinone in Salvia Miltiorrhiza and the phenolic acids in beverages.The thesis is divided into five chapters as follows:Chapter 1: A brief overview of DES and their properties.liquid-solid extraction and dispersion liquid-liquid microextraction were summarized.Finally,the topic background and contents of this research were presented.Chapter 2: In this experiment,the hydrophobic DES formed by thymol and heptanoic acid was used to extract lipophilic tanshinone from Salvia Miltiorrhiza by microwave-assisted method.The DES has extremely low viscosity,not only has good wettability to Danshen powder,but also has good thermal stability in the microwave process.Some parameters,such as the type of extractant,the ratio of extractant,microwave time,microwave power,and the ratio of solid to liquid were carefully investigated.Under the optimal conditions,the limit of detection for the established method was in the range of 0.061-0.083 μg/m L and the extraction rate is 0.18-2.47 mg/g.Therefore,this method has a good extraction effect and stability for the lipophilic tanshinone in Salvia miltiorrhiza.The proposed method had been applied to the determination of tanshinone in Salvia Miltiorrhiza.Chapter 3: In this experiment,the medium and low viscosity hydrophobic DES formed by tetrabutylammonium bromide and octanoic acid is used as the extractant,and the hydrophilic DES formed by tetrabutylammonium bromide and ethylene glycol is used as the dispersant,Sodium chloride,which enhances the extraction effect,is used as a salting-out agent,which can be fully mixed and extracted under the assisted of vortex.Some parameters,such as DES type,DES ratio,DES volume,dispersant type,dispersant ratio,dispersant volume,sodium chloride concentration,p H value,vortex time and sample volume were carefully investigated.Under the optimal conditions,the limit of detection for the established method was in the range of 5.36-8.57 μg/m L and the spiked recoveries were from 83.6-119.4%.It proves that the method is suitable for the determination of phenolic acid in beer.Chapter 4: A method for the determination of phenolic acid by vortex assisted dispersion liquid-liquid microextraction combined with HPLC-UV with hydrophobic DES formed by choline chloride and p-chlorophenol as the extractant is established.The DES easily forms a turbid liquid with water,and p-chlorophenol has a benzene ring structure,and phenolic acid can be extracted from water samples based on π-π interaction.Some parameters,such as the ratio of the extractant,the amount of the extractant,the p H value,and the vortex time were carefully investigated.Under the optimal conditions,the limit of detection for the established method was in the range of 9.87-14.36 ng/m L and the spiked recoveries were from 81.2-119.8%.It was successfully applied to the determination of phenolic acid in beverages.Chapter 5: In this experiment,hexanol is used as the extractant,and the hydrophilic DES formed by tetrabutylammonium bromide and ethylene glycol is used as the dispersant.With the assisted of vortex,the role of the extractant in the dispersant is established.Disperse into smaller droplets for more efficient extraction.Compared with polar organic solvents,DES as a dispersant has a better extraction effect.Some parameters,such as the type of DES type,DES ratio,DES volume,the type of dispersant,the ratio of dispersant,the p H value,and the vortex time were carefully investigated.Under the optimal conditions,the limit of detection for the established method was in the range of 2.54-3.41 μg/m L and the spiked recoveries were from 82.0-116.3%.The proposed method had been applied to the analysis of phenolic acid in tea.Chapter 6: The four experiments of the paper are briefly summarized,concise further the innovations of this paper,and predicting the development direction of solid-liquid extraction and dispersive liquid-liquid microextraction.