Study On Some Local Anesthetics Analysis By Capillary Electrophoresis With Electrochemiluminescence

The effective separation and sensitive determination of several amine-containing local anesthetics are of theory and practicality importance for the pharmacokinetics and clinic study. In this thesis, approach for improving the repeatability of capillary electrophoresis was investigated,the mechanism of the electrochemiluminescence was discussed, and the new methods were developed for the determination of lidocaine and for simultitanos determination of tetracaine and procaine by capillary electrophoresis-electrochemiluminescence detection (CE-ECL).The proposed methods have the advantages of facility, sensitivity and accuracy, and have been used for the analysis of lidocaine in urine, tetracaine and procaine in blood.The main content of this article is as follows:1 A common disadvantage of CE methods is the poor repeatability,including migration time,peak intensity,peak area, which makes the identification of drugs unreliable.We reviewed several factors that may influenced the datas in the capillary electrophoresis with electrochemiluminescence detection. Experiments indicated that certain methods, such as proper pretreatment, capillary and electrode cleaning between continual analysis, fresh electrochemiluminescence reagent and running buffer,the use of interstandard were helpful to achieve a better repeatability. In addition, relevant migration time and electrochemilumine scence intensity could be considered in the process of data analysis to obtain a better precision.2 A rapid, simple and sensitive method was developed for the determination of lidocaine by capillary electrophoresis with electrochemiluminescence detection,which was based on the phenomenon that in PBS medium, lidocaine enhanced the ECL intensity of tris (2,2'-bipyridyl) ruthenium (Ⅱ). Analyte was injected to separation capillary of 40 cm length (25μmi.d.)by electrokinetic injection for 10 s at 10 kV. Under the optimized conditions: ECL detection at 1.25 V,10 mmol/L pH 8.0 phosphate as running buffer, separation voltage at 15 kV,5 mmol/L Ru(bpy)32+with 70 mmol/L pH 8.5 phosphate in the detection cell, the linear range from 1.5 to 740μmol/L for lidocaine and detection limit of 0.1μmol/L was achieved (S/N=3).The RSD of ECL intensity and the migration time for five continuous injections of 3.7 u mol/L were 4.0% and 0.7%, respectively. This method was successfully applied to lidocaine assay in urine samples.3 Tetracaine and procaine, commonly used as local anesthetics, can interdict the conduction of nerve fibre, having narcotism. Based on their sensitizing action to electrochemiluminescence of tris(2,2'bipyridyl)ruthemium(Ⅱ)on platinum electrode, A novel method was developed for the effective separation and simultanous determination of tetracaine and procaine by capillary electrophoresis combined with electrochemiluminescence detection. The mechanism of the electrochemiluminescence was discused. The experiment conditions, such as the pH and concentration of buffer, separation voltage, applied potential,injection voltage,injection time were considered in detail.Under optimized conditions, the proposed method displayed linear ranges from 6.6 to 265.6μmol/L for tetracaine and 0.7 to 219.0μmol/L for procaine.The limits of detection were 1.9μmol/L and 0.2μmol/L,respectively. For practical application, a simple extract step with ethyl acetate was performed to eliminate the protain and the influence of ionic strength in plasma.The recoveries of tetracaine and procaine at different levels were between 91.7 to 95.4%.