A sensitive method for simultaneous determination of azithromycin (AZI), acetylspiramycin (ACE), erythromycin (ERY), and josamycin (JOS) was developed by CE coupled with electrochemiluminescence detection with Ru(bpy)(3) (2+). The parameters related to separation and detection were investigated in detail. The four macrolides were well separated and detected within 6 min under the optimized conditions. The LOD (S/N=3) of AZI, ACE, ERY, and JOS were 1.2 x 10(-9), 7.1 x 10(-9), 3.9 x 10(-8) and 9.5 x 10(-8) mol/L, respectively. The LOQ (S/N=10) of AZI, ACE, ERY, and JOS in human urine were 8.2 x 10(-8), 2.5 x 10(-7), 8.9 x 10(-7) and 1.2 x 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.

A novel, rapid and sensitive method was described for the determination of epinephrine (EP) using flow injection analysis coupled with chemiluminescence (CL) detection, which based on EP enhanced the weak CL emission of luminol-KIO(4) system in NaOH solution. Parameters affecting the CL intensity and reproducibility were optimized systematically. Under the optimized experiment conditions, the net CL intensity was proportional to the concentration of EP in the range of 5.0 × 10(-8) to 1.5 × 10(-6)  mol/L with a detection limit of 1.9 × 10(-9)  mol/L. The relative standard deviation (RSD) was found to be 0.7% for 13 replicate determinations of 3.0 × 10(-7)  mol/L EP. The applicability of the proposed method was illustrated in the determination of EP in pharmaceutical preparation. The recoveries of EP at different levels in EP hydrochloride injection were between 95.4 and 104.7%. One assay procedure takes only 27 s, and the sampling rate was calculated about to be 130 samples/h. The possible mechanism of the enhanced CL intensity was studied by examining CL spectra and UV-vis spectra.

A novel and sensitive method for the simultaneous determination of enoxacin and ofloxacin has been established using capillary electrophoresis (CE) coupled with electrochemiluminescence (ECL) detection 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. The analytes were well separated and detected within 7 min. The limits of detection (S/N = 3) of enoxacin and ofloxacin are 9.0 x 10(-9) and 1.6 x 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 x 10(-7) and 5.4 x 10(-7) mol/L in human urine samples and 4.1 x 10(-7) and 6.9 x 10(-7) mol/L in human serum 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.

A sensitive approach for the simultaneous determination of tilmicosin, erythromycin ethylsuccinate and clindamycin was developed by CE coupled with electrochemiluminescence detection with ionic liquid. The parameters for CE, electrochemiluminescence detection and the effect of ionic liquid were investigated systematically. The three analytes were well separated and detected within 8 min. The limits of detection (S/N=3) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.4x10(-9), 2.3x10(-8) and 1.3x10(-8) mol/L, respectively. The precisions (RSD%) of the peak area and the migration time are from 0.8 to 1.5% and from 0.2 to 0.5% within a day and from 1.8 to 2.7% and from 0.6 to 0.8% in 3 days, respectively. The limits of quantitation (S/N=10) of tilmicosin, erythromycin ethylsuccinate and clindamycin are 3.2x10(-8), 2.9x10(-7) and 9.1x10(-8) mol/L in human urines and 5.5x10(-8), 3.2x10(-7) and 2.1x10(-7) mol/L 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 proposed method was successfully applied to the determination of three analytes in human urine, milk and drugs.

The main purpose of this study was to develop an inexpensive, simple, rapid and sensitive chemiluminescence (CL) method for the determination of glutamine (Gln) using a flow-injection (FI) system. Gln was found to strongly inhibit the CL signal of the luminol-H(2)O(2)-CuSO(4) system in Na(2)B(4)O(7) solution. A new FI-CL method was developed for the determination of Gln. Parameters affecting the reproducibility and CL detection were optimized systematically. Under the optimized conditions, the corresponding linear regression equation was established over the range of 5.0 x 10(-7) to 2.5 x 10(-6) mol/L with the detection limit of 1.8 x 10(-8) mol/L. The relative standard deviation was found to be 1.8% for 11 replicate determinations of 1.5 x 10(-6) mol/L Gln. The proposed method has been satisfactorily applied for the determination of Gln in real samples (Marzulene-s granules) with recoveries in the range of 98.7-108.6%. The minimum sampling rate was about 100 samples/h. The possible mechanism of this inhibitory CL was studied by fluorescence spectrophotometer and UV-vis spectrophotometer.