Synthesis Of Ionic Liquid Of Imidazolium And Its Application In The Analytical Chemistry

Ionic liquids(ILs) are known as room temperature molten salt,which are composed of cations and anions.ILs have been widely used due to their unique chemical and physical properties,such as highly conductivity,good solubility,wide electrochemical widow,good thermal and chemical stability.Ionic liquids can be used as electrolyte,reaction media and catalysts.As a new kind of substance,the basic properties and electrochemical behaviors of ionic liquids are lack of systematic studies, which have limited their applications,especially in pharmaceutical analysis.In this paper,1-buty1-3-methylimidazolium tetrafluoroborate([bmim]BF₄) and 1-buty1-3-methlyimidazolium hexafluorophosphate([bmim]PF₆) ionic liquids were synthesized by the conventional heating method.The electrochemical behaviors of ascorbic acid(AA),quercetin(QUE),and rutin(Rt) in the ionic liquids mentioned above were studied by several electrochemical methods.This work was helpful to broaden the electrochemical theory of ionic liquids,which could be used to evaluate their "green" performance.The main contents of this paper are as follows:1.Imidazole ionic liquid[bmim]BF₄ and[bmim]PF₆ were synthesized from N-methylimidazole by the conventional heating method.Their structures were characterized by IR and NMR.The density and viscosity of[bmim]BF₄-DMSO mixed solution were measured.Meanwhile,the viscosity activation parameter was calculated, and the interaction between solute and solvent was discussed.2.Through cyclic voltammetry,the electrochemical behavior of ascorbic acid was studied on glassy carbon electrode modified by hydrophobic ionic liquid[bmim]PF₆. The effects on its electrochemical behavior,including amount of modification agent, accumulation time and pH value,were investigated.3.An ionic liquid modified carbon paste electrode(IL/CPE) was fabricated with hydrophobe ionic liquid[bmim]PF₆ and liquid paraffin,which took place of pure liquid paraffin as a modifier.The electrochemical behavior of Quercetin(QUE) at the modified electrode was investigated by cyclic voltammetry(CV) and differential pulse voltammetry(DPV).And the parameters of electrode reaction were determined. Moreover,the reaction mechanisms about QUE were discussed.Furthermore,the samples containing QUE were determined by differential pulse voltammetry.4.Using hydrophilic ionic liquid[bmim]BF₄ as a medium,the redox characteristic of rutin(Rt) was investigated in the[bmim]BF₄ by cyclic voltammetry and linear sweep voltammery.The standard rate constant k_s and temperature coefficient of the peak current at 297-323K were calculated in the[bmim]BF₄,and the reaction mechanism of Rt was discussed.In addition,the effects of water and ethanol on the electrochemical behavior of Rt were investigated systematically.More importantly,the linear range and detection limit of Rt were investigated in the ionic liquid[bmim]BF₄-H₂O system.