The Application Of Ionic Liquids Extraction Systems In Food Analysis And Separation

Ionic liquids as a group of unique green solvents have become the focus of researchers.In this paper,ionic liquids were used in different extraction systems for the analysis and seperation of different food samples.The main contents include:（1）Determination of trace chlorophenols in red wine by combining ionic liquid aqueous two-phase extraction as the pretreatment method with HPLCA method of aqueous two-phase system based on hydrophilic ionic liquid[C₄MIM]BF₄ and inorganic salt（NH₄）₂SO₄ for determination of six chlorophenols in red wine was established.The extration efficiency and enrichment factor are influenced by the types and concentrations of salts and ionic liquids,as well as pH value,and these parameters were investigated for optimizing the extraction condition of chlorophenols.Under the optimal conditions,the liner ranges of six chlorophenols were 20-200μg/L,the correlation coefficient（R²）reached 0.999 and the limits of detection had a range of3.68-12.16μg/L.This method was applied to the analysis of the six chlorophenols in real red wines with the spiked recoveries from 87.73%to 103.44%and the relative standard deviation（RSD）from 0.33%to 6.35%.10.9μg/L of 2,4-DCP was detected in one of the red wine samples.This method is simple,convenient,and has high enrichment factor,good repeatability,low sample dosage for chlorophenols.It can be used for the extraction and enrichment of chlorophenols in red wine without any other pretreatment.（2）Countercurrent chromatography separation of lysozyme from egg white by ionic liquid adjusted traditional aqueous two-phase systemA method for separating lysozyme from egg white was established by using ionic liquids as the modifier of the traditional PEG1000-potassium phosphate system.The effect of different ionic liquids and different amount adding into 16%PEG1000-12.5%potassium phosphate system on the distribution behavior of three kinds of egg white proteins were examined,3%[C₄MIM]Cl-16%PEG1000-12.5%potassium phosphate system was selected for countercurrent chromatography separation of egg white.Compared with the system without ionic liquid,the partition coefficient of lysozyme and albumin were reversed,and this was confirmed in countercurrent chromatography separation with lysozyme eluted early than albumin.This system can obtain more pure lysozyme fractions,and the CCC separation effeciency of egg white lysozyme can be improved to certain extent.（3）Extraction and separation of lysozyme from egg white by a novel ionic liquid[C₄MIM]₃CB modified by Cibacron Blue F-3GAA novel ionic liquid[C₄MIM]₃CB was firstly synthesized by modification of[C₄MIM]Cl with Cibacron Blue F-3GA.An extraction method of lysozyme from egg white was established by employing the high specificity between[C₄MIM]₃CB and lysozyme.Through the forward extraction and back extraction under optimal condition,lysozyme can be separated from albumin and conalbumin completely and actual egg white sample was analyzed.250mg egg white powder dissolved in 5mL water was mixed with5m L 8mg/mL[C₄MIM]₃CB in[C₄MIM]PF₆ under shaking for 15min,lysozyme can be extracted selectively into the ionic liquid phase with the other proteins left in the original aqueous phase;through the following back-extraction by 1.5mol/L（pH 7.0）KCl solution,lysozyme can be turned back into aqueous phase.After desalination,concentration and final freeze drying,12.3mg lysozyme with 97.56%purity and 35000U/mg activity can be obtained,purifying factor was 37.39.This method is of high selectivity,and the operation is simple and rapid,which provides a new and more efficient way for the extraction and separation of the egg white lysozyme.