| Capillary electrophoresis (CE) is a highly efficient means of separation, which is performed in capillary tube and driven by electric field. It brings a profound revolution following the GC and HPLC. CE has been proven to be one of the most powerful tools due to the advantages of high resolution, rapid analysis, small sample consumption and simple instruments. However, the concentration sensitivity is relatively poor because of the narrow internal diameter of capillary and small injection volumes. The problem has created a demand for a new form of detection. Improving the detection sensitivity in CE is an important research subject.Electrochemiluminescence (ECL) is of growing importance in many areas of analytical interest because it has the advantage of easy to control, good sensitivity, wide linear range, low reagent consumption and high reaction efficiency. CE-ECL, a new method with high selectivity and high sensitivity, is suitable for the analysis of complex biological and pharmaceutical samples.In this work, the studies on the analysis of macrolides by CE coupled with ECL detection have been described. The main investigations are as follows.1. A new approach for the sensitive determination of azithromycin (AZI), acetylspiramycin (ACE), erythromycin (ERY) and josamycin (JOS) was established by CE-ECL. Under the optimal conditions, the four analytes were well separated within 6 min. The limits of detection (LOD, S/N= 3) of AZI, ACE, ERY and JOS were 1.2×10-9, 7.1×10-9,3.9×10-8 and 9.5×10-8 mol/L, respectively. The limits of quantitation (LOQ, S/N=10) of AZI, ACE, ERY and JOS in human urine were 8.2×10-8,2.5×10-7,8.9 10-7 and 1.2×10-6 mol/L, respectively. The recoveries of the four macrolides in human urine and pharmaceutical tablet samples were 85.0-104.0% at different concentration levels. The proposed method was successfully applied to the determination of four macrolides in human urine and pharmaceutical tablet samples.2. A sensitive approach for the simultaneous determination of tilmicosin, erythromycin ethylsuccinate and clindamycin was developed by CE-ECL with ionic liquid(1-butyl-3-methylimidazolium tetrafluoroborate, BMIMBF4) using azithromycin as internal standard. The conditions for the CE separation, ECL detection and the effect of ionic liquid (IL) were systematically investigated. Under the optimal conditions, the four analytes were well separated within 8 min. The limits of detection (S/N= 3) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.4×10-9,2.3×10-8 and 1.3×10-8 mol L-1, respectively. The limits of quantitation (S/N= 10) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.2×10-8,2.9×10-7 and 9.1×10-8 mol L-1 in human urines and 5.5×10-8,3.2×10-7 and 2.1×10-7 mol L-1 in milk samples, respectively. The recoveries of three analytes at different concentration levels in urine, milk and drugs are between 90.0% and 104.7%. The ECL intensity and separation efficiency can be greatly enhanced by utilization of IL as additive in electrophoretic buffer. The use of azithromycin as internal standard improves the precision of the method. The proposed method was successfully applied to the determination of three analytes in human urine, milk and drug samples.3. A sensitive method for the simultaneous determination of enoxacin and ofloxacin has been established using CE-ECL based on the ECL enhancement of tri(2,2-bipyridyl)ruthenium(II). The conditions for sample solvent type, CE separation and ECL detection were investigated systematically. Under the optimal conditions, EN and OF were well separated within 7 min. The signal intensity and resolution can be greatly improved by utilization of a MeCN-water mixture as sample solvent. The limits of detection (S/N= 3) of enoxacin and ofloxacin are 9.0×10-9 and 1.6×10-8 mol/L, respectively. The precisions (RSD%) of intraday and interday are less than 2.1% and 4.0%, respectively. The limits of quantitation (S/N-10) of enoxacin and ofloxacin are 3.2×10-7 and 5.4×10-7 mol/L in human urine samples,4.1×10-7 and 6.9×10-7 mol/L in human serum samples,5.8×10-8 and 1.1×10-7 mol/L in eye drop samples, respectively. The recoveries of enoxacin and ofloxacin at different concentration levels in human urine, serum and eye drop samples are between 94.0% and 106.7%. The proposed method was successfully applied to the determination of the enoxacin and ofloxacin in human urine, serum and eye drop samples and the monitoring of pharmacokinetics of ofloxacin in human body.
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