Capillary Electrophoresis With Electrochemical Detection Research Articles

Study on Capillary Electrophoresis–Amperometric Detection Profiles from Propolis and its Medicinal Preparations

Propolis is a resinous substance collected by honeybees from leaf buds and cracks in the bark of various plants, the pharmacologically active components in the propolis are flavonoids and phenolic acids and their esters. A simultaneous determination of flavonoids and phenolic acids from propolis and its medicinal preparations by capillary electrophoresis with electrochemical detection (CE-ED) was reported. Under the optimum conditions, the analytes could be separated in a 100 mmol/l borate buffer (pH=8.7) within 25 min. The response was linear over three orders of magnitude with detection limit (S/N=3) ranging from 1×10-7 g/ml to 5×10-7 g/ml for the analytes. This method has been used for the determination of flavonoids and phenolic acids from propolis and its medicinal preparations, and the assay result was satisfactory.

Determination of β-agonists in pig feed, pig urine and pig liver using capillary electrophoresis with electrochemical detection

The fast separation capability of a capillary electrophoresis with electrochemical detection (CE-ED) system was demonstrated by determining five beta-agonists including clenbuterol, metoprolol, ractopamine, isoxsuprine and salbutamol in several real samples. Factors influencing the separation and detection were examined and optimized. Under the optimum conditions, the five beta-agonists could be well separated within 15min at a separation voltage of 14kV in a 100mmoL H(3)BO(3)-Na(2)B(4)O(7) running buffer (pH 9.0). This method was successfully used in the analysis of clenbuterol, metoprolol, ractopamine, isoxsuprine and salbutamol in pig feed, pig urine and pig liver, providing a useful method for monitoring the illegal use of beta-agonists from growth promotion in food-producing animals.

Determination of phenols in Fructus Lycii by capillary electrophoresis with electrochemical detection

A high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been developed for the determination of bioactive phenols in Fructus Lycii samples. Under the optimum conditions, the seven analytes could be well separated within 24 min in a 80 mM borax running buffer. Good linear relationship was established between peak current and concentration of analytes over three orders of magnitude with detection limits (S/N = 3) ranging from 3.5 × 10−8 to 6.0 × 10−8 g/mL for all analytes. The proposed method has been successfully applied for the study on the efficiency of electrochemically active ingredients in polar extracts of Fructus Lycii after a relatively simple pretreatment.

Determination of Bioactive Components in Polygonum perfoliatum L. by Capillary Electrophoresis with Electrochemical Detection

AbstractThe major bioactive components in a Chinese herb named Polygonum perfoliatum L. including ferulic acid, vanillic acid, quercetin, caffeic acid and protocatechuic acid were simultaneously determined by capillary electrophoresis with electrochemical detection (CE‐ED) in this paper. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the five analytes could be separated within 17 min at a separation voltage of 18 kV in 10 mmol· L−1 phosphate buffer (pH 9.2). A 300 µm diameter carbon disk electrode generated good responses at +0.95 V (vs. SCE) to the five analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 7.1×10−8 to 9.3×10−8 g·mL−1 for the analytes. This proposed method could be successfully applied to the analysis of the real samples with relatively simple extraction procedures and satisfactory results.

Quality Analysis of Herbal Medicine Products Prepared from Herba Sarcandrae by Capillary Electrophoresis with Electrochemical Detection

Abstract A capillary electrophoresis with electrochemical detection(CE-ED) method was developed for the quality analysis of herbal medicine products prepared from the same herb of Herba Sarcandrae: Fufang Caoshanhu tablets, Qingrexiaoyanning capsules, and Xuekang oral liquids. Under the optimal analysis conditions, the low detection limit[1.0x10−7 mol/L(S/N=3)] and the wide linear range(1.0x10−7—1.0x10−4 mol/L) were obtained for quality standard compound of isofraxidin. The precisions of the peak current and the migration time(as RSDs) for the real sample analysis were 2.0%—2.6%, and 1.2%—1.8% for isofraxidin, respectively. The contents of isofraxidin detected were 15.77 μg/tablet, 0.48 mg/capsule, 1.2 mg/ampoule(Jiangxi), and 0.44 mg/ampoule(Dalian) for Fufang Caoshanhu tablets, Qingrexiaoyanning capsules, and Xuekang oral liquids from different manufacturers, respectively. Quality estimate was conducted by comparing the contents of isofraxidin in the herbal medicine products with the demanded values of Chinese pharmacopeia. In addition, based on their own unique CE-ED profiles(namely, CE-ED electropherograms) the Xuekang oral liquids from the different manufacturers could be easily identified.

Determination of Active Ingredients of Origanum Vulgare L. and Its Medicinal Preparations by Capillary Electrophoresis with Electrochemical Detection

A method based on capillary electrophoresis with electrochemical detection (CE‐ED) has been developed for the first time for the separation and determination of isovanillic acid, vanillic acid, quercetin, rosmarinic acid, caffeic acid, and protocatechuic acid in Origanum vulgare L. and its medicinal preparations. The effects of working electrode potential, pH level, concentration of running buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmol L−1 borate buffer (pH 8.7) within 21 min. A 300‐µm diameter carbon disk electrode has a good response at +0.95 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 4×10−8 g mL−1 to 2×10−7 g mL−1 for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results.

Determination of isoflavones in red clover by capillary electrophoresis with electrochemical detection

Capillary electrophoresis with electrochemical detection (CE-ED) was employed to analyze isoflavones in red clover ( Trifolium pratense). The effects of potential of working electrode, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Operated in a wall-jet configuration, a 300 μm diameter carbon-disk electrode was used as the working electrode, which exhibits a good response at + 0.85 V (versus saturated calomel electrode) for the analytes. The analytes could be separated in a 50 mmol/l borate buffer (pH 9.5) within 25 min. The response was linear over three orders of magnitude with detection limit (S/N = 3) ranging from 2 × 10 − 5 mg/ml to 5 × 10 − 5 mg/ml for the analytes. This method has been used for the determination of daidzein, genistein and biochanin A in red clover with satisfactory results.

Determination of Pharmacologically Active Ingredients in Sweet Potato (Ipomoea batatas L.) by Capillary Electrophoresis with Electrochemical Detection

Sweet potato (Ipomoea batatas L.), in which vitamin C, chlorogenic acid, caffeic acid, quercetin, and rutin are abundant, is one of the functional food products aimed at introducing human dietary ingredients that aid specific body functions in addition to being nutritious. A method based on capillary electrophoresis with electrochemical detection (CE-ED) to qualitatively and quantitatively determine the pharmacologically active ingredients in sweet potato has been developed by our group. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential, and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well-separated within 20 min at the separation voltage of 18 kV in a 60 mmol L(-1) Borax running buffer (pH 9.0). A good linear relationship was established between peak current and concentration of analytes over 2 orders of magnitude with detection limits (S/N = 3) ranging from 7.14 x 10(-7) to 2.88 x 10(-7) g mL(-1) for all target ingredients. The satisfactory results show that this method is very successful and effective for the analysis of real samples.

Quantitative and qualitative analysis of flavonoid markers in Frucus aurantii of different geographical origin by capillary electrophoresis with electrochemical detection

A capillary electrophoresis with electrochemical detection (CE-ED) method was developed for the simultaneous determination of four major flavonoid markers (synephrine, naringin, hesperidin and naringenin) in Frucus aurantii of different geographical origin. Operated in a wall-jet configuration, a 300 microm diameter carbon disc electrode was used as the working electrode, which exhibits a good response at +0.85 V (versus saturated calomel electrode) for the analytes. Under the optimum conditions, the analytes were baseline separated within 20 min in a 80 mmol/L borax buffer (pH 8.45). The intra-day relative standard deviations (R.S.D.) and inter-day R.S.D.s were based on the analysis of the standard solution on the same day and on the following 6 consecutive days. The intra-day R.S.D.s ranged from 0.8% (naringin) to 3.6% (hesperidin). The inter-day R.S.D.s ranged from 1.2% (hesperidin) to 4.6% (naringenin). Calibration curves were linear in ranges between 0.05 and 1000 microg/mL for the markers. Limits of detection ranged from a low of 1 x 10(-8)g/mL (hesperidin) to a high of 5 x 10(-7)g/mL (naringin). The method was successfully used in the analysis of F. aurantii of different geographical origin with relatively simple extraction procedures, and the assay results were satisfactory.

Electrochemical Detection of Methimazole by Capillary Electrophoresis at a Carbon Fiber Microdisk Electrode

We developed a sensitive, simple and low cost method to determine methimazole based on capillary electrophoresis with electrochemical detection (CE-EC) at a carbon fiber microdisk electrode (CFE). We investigated the effects of detection potential, the concentration and pH value of the phosphate buffer, and injection time as well as separation voltage on the detection of methimazole. Under the optimized conditions: the detection potential at 1.30 V, 10 mmol/ L phosphate buffer (pH 7.0), injection time 30 s at a height of 20 centimeter and separation voltage at 15 kV, the linear range was obtained from 1.0 � 10 � 7 to 2.0 � 10 � 4 mol/L, covering 3 orders of magnitude with a correlation coefficient of 0.9995. The LOD (S/N ¼ 3) obtained was 5.0 � 10 � 8 mol/L. The RSD of migration time and peak current for 2.0 � 10 � 4 mol/L methimazole was 1.04% and 1.54% (n ¼ 10), respectively. The method was also used to analyze methimazole tablets and human urine sample.

Determination of 8-oxoguanine and 8-hydroxy-2'-deoxyguanosine in the rat cerebral cortex using microdialysis sampling and capillary electrophoresis with electrochemical detection.

A rapid and sensitive method to determine 8-oxoguanine (8oxoG) and 8-hydroxydeoxyguanosine (8OHdG), biomarkers for oxidative DNA damage, in cerebral cortex microdialysate samples using capillary electrophoresis (CE) with electrochemical detection (CEEC) was developed. Samples were concentrated on-column using pH-mediated stacking for anions. On-column anodic detection was performed with a carbon fiber working electrode and laser-etched decoupler. The method is linear over the expected extracellular concentration range for 8oxoG and 8-OHdG during induced ischemia-reperfusion, with R.S.D. values <or=5% and limit of detection of 0.5 nM for both analytes. Basal concentrations of 8oxoG in rat cerebral cortex microdialysate were determined to be 3.2+/-0.6 nM. Actual 8oxoG concentration in the brain was estimated to be 5.5+/-1.3 nM based on in vivo delivery probe calibration. 8OHdG was not detected under basal conditions in the rat cerebral cortex extracellular fluid (ECF). These results were confirmed by LC with tandem mass spectrometry.

Determination of uric acid and p-aminohippuric acid in human saliva and urine using capillary electrophoresis with electrochemical detection : Potential application in fast diagnosis of renal disease

The monitoring of uric acid (UA) and p-aminohippuric acid (PAH) levels in biological samples is routinely carried out in clinical laboratories as an indication of renal disease. With the aim of investigation of the correlation between the trace amounts of UA and PAH in human saliva or urine and renal diseases, we carried out the determination of UA and PAH in human saliva and urine by using capillary electrophoresis with electrochemical detection (CE-ED) in this work. Under the optimum conditions, UA, PAH and three coexisting analytes could be well separated within 21 min at the separation voltage of 14 kV in 80 mmol/L borax running buffer (pH 9.2). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits ( S/ N = 3) ranged from 5.01 × 10 −7 to 2.00 × 10 −6 mol/L for all analytes. The result shows that this proposed method could be successfully applied for the study on the correlation between the levels of UA and PAH in human saliva and urine and renal diseases, and provide an alternative and convenient method for the fast diagnosis of renal disease.

Determination of urinary 8-hydroxy-2′-deoxyguanosine by two approaches—capillary electrophoresis and GC/MS: An assay for in vivo oxidative DNA damage in cancer patients

8-Hydroxy-2'-deoxyguanosine (8OHdG) has been considered as an excellent marker of oxidative DNA damage associated with age-related diseases such as cancer. In this paper, two sensitive methods-capillary electrophoresis with electrochemical detection (CE-ECD) and gas chromatography/mass spectrometry (GC/MS) were developed for urinary 8OHdG analysis. The R.S.D. of the spiked recovery of the two methods for determining urinary 8OHdG was 4.03% and 8.25%, respectively, and the results from the two methods have a good consistency (r=0.999, P<0.01). The developed CE-ECD method was applied to investigate the urinary 8OHdG levels in different cancer patients and follow up the response of therapy. It was found that the excretion levels of urinary 8OHdG in cancer patients were significantly higher than those in healthy persons (35.26+/-27.96 nM versus 13.51+/-5.08 nM, P<0.05), and cancer patients receiving surgical therapy and chemotherapy showed a significant decrease in urinary 8OHdG.

Determination of Phenolic Compounds in the Hull and Flour of Buckwheat (Fagopyrum esculentum Moench) by Capillary Electrophoresis with Electrochemical Detection

A simple, reliable and reproducible method, based on capillary electrophoresis with electrochemical detection (CE‐ED), for the determination of phenolic compounds of buckwheat (Fagopyrum esculentum Moench) hulls and flour was reported. The mainly phenolic components consist of (−)‐epicatechin, rutin, hyperoside, and quercetin. Operated in a wall‐jet configuration, a 300 µm diameter carbon disk electrode was used as the working electrode, which exhibits good response at +0.90 V (versus SCE) for all relevant analytes. The potential effects of working electrode, pH and concentration of buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the analytes can be separated in a 50 mmol/L borate buffer (pH = 8.7) within 16 min. The response was linear over three orders of magnitude with detection limit (S/N = 3) ranging from 2 × 10−7 g/mL to 5 × 10−7 g/mL for all analytes. This method has been used for the determination of phenolic compounds in buchwheat (Fagopyrum esculentum Moench) hulls and flour, and the assay result was satisfactory.

Determination and Differentiation of Flos Chrysanthemum Based on Characteristic Electrochemical Profiles by Capillary Electrophoresis with Electrochemical Detection

A high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been developed for the analysis of bioactive ingredients in Flos Chrysanthemum in this work. The effects of several factors such as the acidity and concentration of running buffer, the separation voltage, the applied potential, and the injection time were investigated. Under the optimum conditions, the eight analytes could be well separated within 20 min at the separation voltage of 14 kV in a 50 mmol/L Borax running buffer (pH 9.2). A 300 microm diameter carbon disk electrode has a good response at a potential of +950 mV (vs SCE) for all analytes. Good linear relationship was established over 3 orders of magnitude with detection limits (S/N = 3) that ranged from 1.9 x 10(-7) to 3.0 x 10(-8) g/mL. This proposed method has been successfully applied for the determination and differentiation of six kinds of popular Flos Chrysanthemum samples based on their characteristic electrochemical profiles, and the results are satisfactory.

Simultaneous determination of phytoestrogens in different medicinal parts of Sophora japonica L. by capillary electrophoresis with electrochemical detection

A high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been developed for the determination of phytoestrogens from the pericarps and seeds of Sophora japonica L. in this work. Genistin, genistein, rutin, kaempferol and quercetin are important bioactive constituents in these plants. The effects of several factors such as the acidity and concentration of running buffer, the separation voltage, the applied potential and the injection time on the CE-ED procedure were investigated. Under the optimum conditions, the five analytes could be well separated within 18 min in a 75 cm length capillary (i.d. 25 microm) at the separation voltage of 16 kV in a 50 mmol L(-1) borax running buffer (pH 9.0). A 300 microm diameter carbon disk electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at the potential of +950 mV (vs SCE). Detection limits (S/N = 3) ranged from 1.1 x 10(-7) to 2.8 x 10(-7) g mL(-1) for all fi ve analytes. This method was successfully used to analyse dried Flos sophorae immaturus, pericarps and seeds of dried Fructus sophorae after a relatively simple extraction procedure, and the assay results were satisfactory.

Determination of uric acid in human saliva by capillary electrophoresis with electrochemical detection: potential application in fast diagnosis of gout

The clinical manifestations of gout result from the formation and deposition of uric acid (UA) crystals. The monitoring of UA level in less invasive biological samples such as saliva is suggested for diagnosis and therapy of gout, hyperuricemia and the Lesch-Nyhan syndrome. In order to investigate the correlation between trace amounts of UA in human saliva and urine and explore the potential application in fast diagnosis of gout, capillary electrophoresis with electrochemical detection (CE-ED) was applied for the determination of UA in human saliva and urine in this work. Under the optimum conditions, UA and three coexisting analytes could be well separated within 14 min at the separation voltage of 14 kV in 80 mmol L(-1) borax running buffer (pH 7.8). A good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N = 3) ranging from 1.09 x 10(-7) to 5.0 x 10(-7) mol L(-1) for all analytes. This proposed method has been successfully applied for study of the correlation between the UA content of human saliva and urine, providing an alternative and convenient method for rapid diagnosis of gout.

Determination and Comparison of Phytoestrogens in Both Crude and Parched Flos Sophorae Immaturus by Capillary Electrophoresis with Electrochemical Detection

A method using high-performance capillary electrophoresis with electrochemical detection (CE-ED) has been developed for content comparison of phytoestrogens in both crude and parched Flos sophorae immaturus. Genistin, genistein, rutin, kaempferol and quercetin are important active constituents in this plant. The effects of several factors, such as acidity and concentration of running buffer, separation voltage, applied potential and injection time, were investigated to find the optimum conditions. Detection limits (S/N=3) ranged from 1.1 × 10−7 to 2.8 × 10−7 g mL−1 for all five analytes. This method was successfully used to analyse both crude and parched Flos sophorae immaturus after a relatively simple extraction procedure, and the assay results were satisfactory.

Determination of polyphenols in apple juice and cider by capillary electrophoresis with electrochemical detection

A simultaneous determination of phloridzin, (−)-epicatechin, chlorogenic acid and myricetin in apple juices and ciders by capillary electrophoresis with electrochemical detection (CE-ED) was reported. Effects of several important factors such as the pH and concentration of running buffer, separation voltage, injection time and detection potential were investigated to acquire the optimum conditions. Under the optimum conditions, the analytes could be separated within 20 min in a 75 cm length capillary at a separation voltage of 18 kV in a 50 mmol/l borate buffer (pH 8.7). A 300 μm diameter carbon disk electrode generates good response at +0.90 V (vs. SCE) for all analytes. The relationship between peak currents and analyte concentrations was linear over about three orders of magnitude with detection limits ( S/ N = 3) ranging from 1 × 10 −7 to 5 × 10 −7 g/ml for all analytes. This proposed method demonstrated long-term stability and reproducibility with relative standard deviations of less than 4% for both migration time and peak current ( n = 7). It has been successively used for the determination of the analytes in apple juices and ciders, and the assay result was satisfactory.

Determination of Bioactive Flavonoids in Rhododendron Dauricum L. by Capillary Electrophoresis with Electrochemical Detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed for the determination of bioactive flavonoids in the traditional Chinese herbal medicine, Rhododendron dauricum L. The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be separated in a 70 mmol L−1 borate buffer (pH=9.2) within 20 min. A 300 μm diameter carbon disk electrode has a good response at + 0.90 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N = 3) ranging from 2 × 10−8 g mL−1 to 2 × 10−7 g m−1 for the analytes. The method has been successfully applied for the analysis of real sample, with satisfactory results.