End-column Electrochemiluminescence Research Articles

Determination of Verapamil Hydrochloride and Norverapamil Hydrochloride in Rat Plasma by Capillary Electrophoresis With End-Column Electrochemiluminescence Detection and Their Pharmacokinetics Study.

In this study, we developed a new method for simultaneous determination of verapamil hydrochloride (VerHCl) and its metabolite norverapamil hydrochloride (NorHCl) by using the capillary electrophoresis-electrochemiluminescence. Under optimized experimental conditions, the linear ranges of the VerHCl and NorHCl concentrations were 0.015-10.0 and 0.060-10.0μg/mL, respectively. The linearity relations were determined using the respective regression equations y=581.2x+19.94 and y=339.4x+29.16. The respective limits of detection (S/N=3) were 0.006 and 0.024μg/mL. The proposed method was used to study the pharmacokinetics of both agents in rat plasma. The maximum concentration (Cmax), half-life time (T1/2) and time to peak (Tmax) were 683.21±74.81ng/mL, 0.52±0.21h and 2.49±0.32h for VerHCl and 698.42±71.45ng/mL, 1.14±0.26h and 2.83±0.23h for NorHCl, respectively, following oral administration of 10mg/kg VerHCl.

Determination of Four Residues of Fluoroquinolones with Similar Structure in Fish by Modified QuEChERS Protocol Coupled toCapillary Electrophoresis(CE) with End-Column Electrochemiluminescence (ECL)

Determination of Four Residues of Fluoroquinolones with Similar Structure in Fish by Modified QuEChERS Protocol Coupled toCapillary Electrophoresis(CE) with End-Column Electrochemiluminescence (ECL)

Simultaneous Determination of Tramadol and Diltiazem in Waterbodies by Capillary Electrophoresis with End-Column Electrochemiluminescence Detection

Simultaneous Determination of Tramadol and Diltiazem in Waterbodies by Capillary Electrophoresis with End-Column Electrochemiluminescence Detection

Capillary electrophoresis with end-column electrochemiluminescence for ultrasensitive determination of urapidil hydrochloride in rat plasma and its application to pharmacokinetics study.

A simple, sensitive and selective method for determination of urapidil hydrochloride was developed using capillary electrophoresis with electrochemiluminescence (CE-ECL) technique for the first time. Under the optimized experimental conditions, the ECL intensity was linear with the concentration of urapidil hydrochloride in the range from 0.050 to 50.0ng/mL and the detection limit was 0.014ng/mL (S/N=3). The proposed method was used for studying pharmacokinetics of urapidil hydrochloride in rat plasma and the main pharmacokinetic parameters of the peak concentration (Cmax), half life time (T1/2) and peak concentration time (Tmax) were 240.45±21.15ng/mL, 0.58±0.16h and 1.08±0.13h, respectively. The recoveries of urapidil hydrochloride in the diluted extracts of rat plasma samples ranged from 96.68 to 98.82%. The RSD was lower than 3%.

A Method for the Determination of Atropine in Pharmaceutical Preparation Using CE-ECL

In this paper, a sensitive determination method for atropine based on end-column electrochemiluminescence of tris (2,2’-bipyridyl) ruthenium (II) detection is described. The conditions affecting separation and detection were investigated. Favorable ECL intensity of atropine was achieved in a solution consisting 5 mmol/L Ru (bpy)32+ and 50 mmol/L phosphate at applied voltage of 1.20V. The standard curve was linear between 1 and 20 μmol/L for atropine. The calibration equation and regression coefficients were: y = 128.38x−36.76 and R = 0.998 in terms of peak height response as a function of analyte concentration. A detection limit of 5×10−8 mol/L (S/N= 3) was achieved. The proposed method was applied satisfactorily to the determination of atropine in three pharmaceutical preparations.

Determination of Tramadol in Human Serum by Capillary Electrophoresis with the End-Column Electrochemiluminescence Detection

A capillary electrophoresis (CE) coupled with end-column electrochemiluminescence (ECL) detection method for the analysis of tramadol (TMD) has been investigated. ECL detection was working electrode biased at 1.2 V in a 20mmol·L-1 sodium phosphate buffer (pH = 8.0) containing 5 mmol·L-1 Ru (where bpy = 2,2’-bipyridyl). Linear correlation (r ≥ 0.997) between ECL intensity and drug concentration was obtained in the range 3 × 10-4 - 6 × 10-6 mol·L-1. The limits of detection (LODs) for tramadol in water was 3.012 × 10-8 mol·L-1(S/N = 3). The relative standard deviation values on peak size (10-5 mol·L-1 level) and migration time for the tramadol were 4.58% and 1.39% (n = 10), respectively. Applicability of the CE-ECL method to the analysis of human serum spiked with tramadol was examined

Determination of imipramine and trimipramine by capillary electrophoresis with electrochemiluminescence detection

The tricyclic antidepressants (TCA) imipramine (Imi) and trimipramine (Tri) were successfully analyzed by capillary electrophoresis (CE) coupling with Tris(2,2-bipyridyl) ruthenium(II)-based (Ru(bpy)32+) end-column electrochemiluminescence (ECL) detection. The addition of β-CD to the running buffer was found to enable baseline separation of the two analytes and the addition of acetonitrile (ACN) as an organic additive to improve the repeatability and sensitivity of the CE method. Under the optimized separation and detection conditions (50mM PBS (pH=7.0) and 2mM Ru(bpy)32+ in the ECL detection cell, 20mM Tris (pH=2.0), 0.2mM β-CD and 20% ACN (v/v) as running buffer), wide linear ranges of 0.1–5μM and 0.1–5μM were achieved, with the correlation coefficients of 0.9990 (n=8) and 0.9980 (n=8) for Imi and Tri, respectively. Detection limits 5nM and 1nM (S/N=3) were obtained for Imi and Tri, respectively. The method was also successfully applied for the determination of Imi in pharmaceutical dosage form.

Capillary Electrophoresis Determination of Berberine in Pharmaceuticals with End‐Column Electrochemiluminescence Detection

AbstractCapillary electrophoresis with end‐column electrochemiluminescence (ECL) detection was applied to the determination of berberine, which causes an enhancement of the ECL of tris(2,2‐bipyridyl)ruthenium(II). The assay is accomplished within 4 min with an injection volume of 3.3 nL. The linear analytical range is from 2.0 × 10−8 to 1.0 × 10−6 g mL−1 with a detection limit of 5 × 10−9 g mL−1. The relative standard deviations of the ECL signal and the migration time are 4.4% and 2.7% for 5.0 × 10−7 g mL−1 berberine solution (n = 7). The method was applied to the determination of berberine in tablets and in rhizoma coptidis.

Detection of clindamycin by capillary electrophoresis with an end-column electrochemiluminescence of tris(2,2′-bypyridine)ruthenium(II)

Coupled capillary electrophoresis (CE) with end-column electrogenerated chemiluminescence (ECL) was adopted for the quantitative detection of clindamycin. Clindamycin enhanced ECL intensity of tris(2,2′-bypyridine)ruthenium(II) (Ru(bpy) 3 2+) as a coreactant. Under the optimized conditions, the ECL intensity was linear with the concentration of clindamycin over the range from 5.0 × 10 −7 to 1.0 × 10 −4 M with a detection limit of 1.4 × 10 −7 M. The proposed CE–ECL was successfully applied for the detection of clindamycin in pharmaceutical and clinic samples. The interaction of clindamycin with hemoglobin was also investigated. The binding constant of clindamycin with hemoglobin was estimated to be 3.6 × 10 3 M −1.

Determination of erythromycin in rat plasma with capillary electrophoresis–electrochemiluminescence detection of tris(2,2′-bipyridyl) ruthenium(II)

A fast and sensitive approach for determination of erythromycin in rat plasma was described. The method used capillary electrophoresis coupled with end-column electrochemiluminescence (ECL) detection of Ru(bpy) 3 2+. The separation column used had an inner diameter of 75 μm. The running buffer was 15 mmol/L sodium phosphate (pH = 7.5). The solution in the detection cell was 50 mmol/L sodium phosphate (pH = 8.0) and 5 mmol/L Ru(bpy) 3 2+. ECL intensity varied linearly with erythromycin concentration from 1.0 ng/mL to 10 μg/mL. The detection limit (S/N = 3) was 0.35 ng/mL. The relative standard deviations, of ECL intensity and migration time for eight consecutive injections of 1.0 μg/mL erythromycin ( n = 8), were 1.3% and 1.8%, respectively. The method was successfully applied to erythromycin determination in rat plasma. The recovery ranged from 92.5 to 97.5%.

Capillary electrophoresis with end-column electrochemiluminescence for the analysis of chloroquine phosphate and the study on its interaction with human serum albumin

This paper describes a novel and sensitive method for the estimation of chloroquine phosphate (CQ) using capillary electrophoresis with end-column electrochemiluminescence (ECL) detection. Under the optimized condition, linear calibration curve was obtained for the system over two orders of magnitude with a detection limit of 3 × 10 −7 M (S/N = 3). The relative standard deviations of the ECL intensity and the migration time were 1.4% and 0.05%, respectively ( n = 6, 5 × 10 −5 M CQ). Successful separation of chloroquine phosphate, difenidol hydrochloride and clomifene citrate was obtained at pH 7.0. Using the proposed electrochemiluminescence system, a simple method was proposed to study the interaction between chloroquine phosphate and human serum albumin (HSA), and the number of binding sites and binding constant were estimated to be 32.6 and 7.7 × 10 3 M −1, respectively.

Determination of norfloxacin in human urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach that can be used to detect norfloxacin in human urine using capillary electrophoresis with end-column electrochemiluminescence (ECL) detection of Ru(bpy)(3)(2+) is described. The separation column was a 75-microm i.d. capillary. The running buffer was 15 mmol L(-1) sodium phosphate (pH 8.2). The solution in the detection cell was 50 mmol L(-1) sodium phosphate (pH 8.0) and 5 mmol L(-1) Ru(bpy)(3)(2+). The ECL intensity varied linearly with norfloxacin concentration from 0.05 to 10 micromol L(-1). The detection limit (S/N=3) was 0.0048 micromol L(-1), and the relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 micromol L(-1) norfloxacin (n=11) were 2.6% and 0.8%, respectively. The method was successfully applied to the determination of norfloxacin spiked in human urine without sample pretreatment. The recoveries were 92.7-97.9%.

Determination of benzhexol hydrochloride by capillary zone electrophoresis with an end-column electrochemiluminescence detection

A capillary zone electrophoresis with end-column electrochemiluminescence (ECL) detector was described for the determination of benzhexol hydrochloride. The detection was based on the tris(2,2′-bypyridine)ruthenium(II) [Ru(bpy) 3 2+] ECL reaction with the analyte. Electrophoresis was performed using a 25 μm i.d. uncoated capillary. 10 mM sodium phosphate buffer (pH=8.0) was used as the running buffer. The solution in the detection cell was 80 mM sodium phosphate (pH=8.0) and 5 mM Ru(bpy) 3 2+. A linear calibration curve of three-orders of magnitude was obtained (with a correlation coefficient of >0.999) from 1.0×10 −8 to 1.0×10 −5 M and the limit of detection was 6.7×10 −9 M ( S/ N=3). This just provides an easy and sensitive method to determine the active ingredient in pharmaceutical formulations.

New technique for capillary electrophoresis directly coupled with end-column electrochemiluminescence detection.

A new end-column electrochemiluminescence (ECL) detection technique coupling to capillary electrophoresis (CE) is characterized. A 300 microm diameter Pt working electrode was used to directly couple with a 75 microm inner diameter separation capillary without an electric field decoupler. The hydrodynamic cyclic voltammogram (CV) of Ru(bpy) 3 2+ showed that electrophoretic current did not affect the ECL reaction. The presence of high-voltage (HV) field only resulted in the shift of the ECL detection potential. The distance of capillary to electrode was an important parameter for optimizing detection performance as it determined the characteristics of mass transport toward the electrode and the actual concentration of Ru(bpy) 3 2+ in the detection region. The optimum distance of capillary to electrode was decided by the inner diameter of the capillary, too. For a 75 microm capillary, the working electrode should be placed away from the capillary outlet at a distance within the range of 220-260 microm. The effects of pH value of ECL solution and molecular structure of analytes on peak height and theoretical plate numbers were discussed. Using the 75 microm capillary, under the optimum conditions, the method provided a linear range for tripropylamine (TPA) between 1 x 10(-10) and 1 x 10(-5) mol/L with correlation coefficient of 0.998. The detection limit (signal-to-noise ratio S/N = 3) was 5.0 x 10(-11) mol/L. The relative standard deviation in peak height for eight consecutive injections was 5.6%. By this new technique lidocaine spiked in a urine sample was determined. The method exhibited the linear range for lidocaine from 5.0 x 10(-8) to 1.0 x 10(-5) mol/L with correlation efficient of 0.998. The limit of detection (S/N = 3) was 2.0 x 10(-8) mol/L.