Determination of baicalin, chlorogenic acid and caffeic acid in traditional chinese medicinal preparations by capillary zone electrophoresis

Summary A capillary zone electrophoresis (CZE) method was developed for the simultaneous assay of three bioactive components—baicalin, chlorogenic acid and caffeic acid—in seven traditional Chinese medicinal preparations. The analytes were separated successfully within 3.5 min using 10 mM borate buffer (pH8.6). Regression equations revealed linear relationships (correlation coefficients 0.9942–0.9996) between the peak area and concentration of the three analytes. The relative standard deviations of the migration times and the peak areas of the three constituents were 1.12–2.68% and 1.62–5.73%, respectively. Recovery of the three constituents ranged from 89 to 107%. The extraction efficiencies of different extraction solutions are also discussed. The contents of the three components in seven different Chinese medicinal preparations containing Honeysuckle flower and/orScutellariae radix were determined by the CZE method with satisfactory results.     

Determination of rutin and forsythin in fruit ofForsythia suspensa(Thunb.) Vahl by capillary electrophoresis-electrochemical detection

Summary Capillary electrophoresis-amperometric detection is evaluated for simultaneous determination of rutin and forsythin. The cyclic voltammogram, hydrodynamic voltammogram, effect of pH, buffer concentration and SDS, and percent organic modifier on separation and detection were studied. Conditions were optimized as follows: 1.2 V detection potential; separation at 12 kV; 5 s at 15 kV for sample injection time and sample injection voltage; mobile phase 20 mM boric acid buffer; pH 8.4, containing 40 mM SDS and 10% (v/v) acetontrile. The method gave low detection limit as 0.001 mg mL⁻¹ and 0.0005 mg mL⁻¹ (S/N=3), wide linear range 0.005–0.5 mg mL⁻¹ for rutin and forsythin, respectively. The relative standard deviations of peak current and migration time for 8 consecutive injections of the standard solution containing 0.1 mg mL⁻¹ each compound were 4.78%, 3.63% and 6.40%, 2.95% for rutin and forsythin, respectively. In addition, levels of the two compounds in traditional Chinese herbal drugs were easily determined.     

Determination of azelaic and sorbic acid in pharmaceduticals by capillary electrophoresis

Summary Capillary electrophoresis with indirect UV detection at 254 nm was applied to simultaneous determination of ∼20% of azelaic acid and ∼0.1% of sorbic acid in AKNOREN cream. The acids were separated in fused silica capillary (45 cm × 50 μm) at 30 kV. Optimised back-ground electrolyte was 30 mM benzoate buffer (pH∼6, adjusted with TRIS) containing 7 mM β-cyclodextrin and 5% of methanol; internal standard was 2-hydroxysobutyric acid (HIBA). Rectilinear calibration ranges were 0.4–4 mg mL⁻¹ for azelaic acid and 2–20 μg mL⁻¹ for sorbic acid and the recoveries were 97.2–100.5%. A single analysis took <15 min.     

Determination of rhein, baicalin and berberine in traditional Chinese medicinal preparations by capillary electrophoresis with two-marker technique

A CZE method for the identification and determination of three bioactive components, rhein, baicalin and berberine, was developed, with 10 mM borate at pH 9.20 as background electrolyte and direct UV detection at 254 nm. The two-marker (glycyrrhizin acid and cefalexin) technique was used to improve the repeatability of analysis. When the migration indices were used, the repeatability was greatly enhanced compared with migration times. The apparent dissociation contents of rhein and baicalin were also obtained. This method has been successfully applied to the simultaneous analysis of the three components with the recoveries from 96.7% to 104.6%.     

毛细管电泳法分离测定芦丁、槲皮素和连翘苷

用毛细管电泳紫外检测法同时测定了芦丁、槲皮素和连翘苷，研究了各种条件的影响，得到了优化的实验条件，在20mmol/L的Na2B4O7(H3B03调节至pH8．40)-30mmol/L十二烷基硫酸钠-10％乙腈(1 9)的缓冲溶液中，分离电压为12kV时，芦丁、槲皮素和连翘苷在10min内得到了良好的分离，检测波长为254nm，芦丁、槲皮素和连翘苷分别在0．01-1．0mg/mL，0．01-1．0mg／mL和0．05-1．0mg/mL质量浓度范围内与电泳峰高呈现良好线性关系，检测下限分别为0．005mg/mL，0．005mg/mL和0．01mg／mL，应用于实际样品的测定。     

Determination of muscimol and ibotenic acid in mushrooms of Amanitaceae by capillary electrophoresis

In this study, the CZE method for rapid quantitative and qualitative determination of ibotenic acid and muscimol in Amanita mushrooms naturally grown in Poland was developed. The investigations included the species of A. muscaria, A. pantherina, and A. citrina, collected in southern region of Poland. The studied hallucinogenic compounds were effectively extracted with a mixture of methanol and 1 mM sodium phosphate buffer at pH 3 (1:1 v/v) using ultrasound‐assisted procedure. The obtained extracts were separated and determined by CZE utilizing a 25 mM sodium phosphate running buffer adjusted to pH 3 with 5% content of acetonitrile v/v. The calibration curves for both analytes were linear in the range of 2.5–7000 μg/mL. The intraday and interday variations of quantitative data were 1.0 and 2.5% RSD, respectively. The recovery values of analyzed compounds were over 87%. The identities of ibotenic acid and muscimol were confirmed by UV spectra, migration time, and measurements after addition of external standard.     

胶束扫集毛细管电泳分离测定绿原酸和咖啡酸

采用胶束扫集毛细管电泳分离测定双黄连口服液中的绿原酸和咖啡酸.试验条件为:重力进样时间40 s;以20 mmol/L NaH_2PO_4,100 mmol/L 十二烷基磺酸钠(SDS)为电泳缓冲液(含体积分数15%甲醇,pH 2.20),分离电压-20 kV,检测波长214 nm,讨论了pH、SDS浓度、样品溶剂等对分离效果的影响.在优化条件下,绿原酸和咖啡酸的检出限分别达到1.02和0.168 μg/mL,线性范围分别为5.86～51.5 μg/mL和1.27～14.5 μg/mL.     

Fast determination of chlorogenic acid in tobacco residues using microwave-assisted extraction and capillary zone electrophoresis technique

In this work, for the first time, capillary zone electrophoresis (CZE) technique combined with microwave-assisted extraction (MAE) was developed for the fast quantification of chlorogenic acid (CA) in tobacco residues. CA in tobacco residue samples were extracted by MAE technique, and then analyzed by CZE. As a new sample preparation method for tobacco residues, the MAE procedure is optimized, validated and compared with conventional methods including ultrasonic extraction (USE) and reflux extraction (RE). It is found that MAE gives the best result due to the highest extraction efficiency within shortest extraction time (only 4.0 min). Here, CA is determined by CZE based on the calibration curve of its authentic standard. The method linearity, detection limit, precision and recovery are studied. The results show that the combined MAE and CZE method has a linearity (R² 0.991, 0.003-0.5 mg ml⁻¹), a limit of detection (0.003 mg ml⁻¹), a limit of quantification (0.01 mg ml⁻¹), good precision (R.S.D. = 4.28%) and a finer recovery (89.0%). The proposed method was successfully applied to the analysis of CA in tobacco residue samples. The experiment results have demonstrated that the CZE combined with MAE is a convenient, fast, economical and reliable method for the determination of CA in tobacco residues.     

Simultaneous separation of nitrate, nitrite and ammonium by capillary electrophoresis

Summary A capillary electrophoretic method for the simultaneous separation of nitrate, nitrite and ammonium has been developed. Direct (NO₃ ⁻, NO₂ ⁻) and indirect (NH₄ ⁺) UV detection at 214 nm in conjunction with electromigration sampling from both ends of the capillary was used. Two electrolyte systems based on imidazole-sulfate (pH 3.8) and copper(II)-ethylenediamine-chloride (pH 8.0) were investigated. Optimisation of the experimental parameters such as electrolyte concentration, pH, nature of the counter-ion, was studied. The method permits excellent separation of three nitrogen species in only 4 min. The analytical performance of both electrolyte systems is compared in terms of migration time and peak area repeatability and detectability. Alkaline electrolyte shows a better overall analytical performance.     

Determination of active components in Chinese medicinal preparations by capillary electrophoresis

The determination of paeoniforin, paeonol, and censenoside Rg₁ in traditional Chinese medicinal preparations, Tze Po San Pien pills and Liuwen Dihuang pills has been investigated by micellar electrokinetic capillary electrophoresis with borate buffer (20 mM), sodium dodecylsulfate (30 mM) and acetonitrile (20%) as background electrolytes (pH 9.30), 20 kV applied voltage and 203 nm UV detection. The effects of SDS concentration, borate, buffer pH, and organic modifier on electrophoretic behavior and separation are discussed. Regression equations revealed linear relationships between the peak-area of each component and the content with the correlation coefficients from 0.9982 to 0.9999. In addition, the levels of the active compounds in two kinds of traditional Chinese medicinal preparations were easily determined with the recoveries from 93.1% to 108.2%.      

Determination of organic acid drug counter-ions by capillary electrophoresis

Summary A capillary electrophoresis method is described for the novel application of quantifying levels of the simple organic acid counter-ions of a variety of basic drugs. These counter-ions are organic acids such as succinic and maleic. The method uses indirect UV detection and an electroosmotic flow modifier. Acceptable precision and detector linearity were obtained using internal standards. Method validation was completed and acceptable data was generated. The method is now in routine use for this type of testing.     

毛细管区带电泳法测定消毒剂中三氯新

建立了消毒剂中三氯新的毛细管电泳分析方法。探讨了缓冲介质和电泳参数对三氯新测定的影响。以15mmol/LNa2HPO4(pH6.0)-乙腈(V(Na2HPO4)∶V(乙腈)=50∶50)为电泳缓冲液,三氯新在12kV电压下电泳,于254nm检测波长处测定,6min可以完成分析。本方法的检出限为0.04mg/L,线性范围0.04～2.00mg/mL(r=0.997),加标回收率在90.9%～108.2%范围内,测定值的相对标准偏差分别为峰高7.7%,迁移时间5.5%。将本法与高效液相色谱法进行比较,样品测定结果的相对误差小于10%。将所建立的方法已用于消毒剂样品中三氯新的测定。     

非水体系毛细管电泳-紫外检测法测定苯甲酸和苯甲醛

建立了用非水相体系高效毛细管电泳-紫外检测法同时测定苯甲酸和苯甲醛的新方法，考察了运行电压、非水相介质和电解质等因素的影响，在25℃下，以V（乙腈）：V（碳酸丙烯酯）=1：1的混合液为溶剂，缓冲体系中含15mmol／L十六烷基三甲基溴化铵体积分数1％乙酸，重力进样30S，运行电压20kV，毛细管总长45cm有效长度30cm，φ75μm，检测波长285nm。苯甲酸线性范围为5～40μg／mL，线性方程为：Y=13．473ρ＋13．336，相关系数r=0．9985，检出限为0．92μg／mL，RSD为3．8％。苯甲醛的线性范围75～1125μg／mL线性方程为：Y=5．2449ρ＋564．01，相关系数r=0．9997，检出限为15．60μg／mL，RSD为3．5％。已用于经空气氧化后的苯甲醛中苯甲酸和苯甲醛的测定。     

毛细管电泳同时分离测定阿魏酸、异阿魏酸的研究

建立了同时分离测定阿魏酸、异阿魏酸的毛细管电泳(CZE)新方法。以20 mmol/L硼砂为背景电解质,体积分数15%异丙醇为有机改性剂,分离电压为20 kV,在219 nm波长下紫外检测。对硼砂浓度、有机溶剂体积分数、分离电压等因素对分离的影响做了系统的研究,最后确立了阿魏酸、异阿魏酸的最佳分离条件。阿魏酸、异阿魏酸分别在2.40~24.0μg/mL、1.80~18.0μg/mL范围内线性关系良好(r=0.9995和r=0.9991),回收率分别为96.61%~101.9%,98.80%~101.8%。方法已用于升麻中阿魏酸、异阿魏酸的测定。     

Determination of barbituric acid and 2-thiobarbituric acid with end-column electrochemical detection by capillary electrophoresis

Capillary electrophoresis (CE) with end-column electrochemical detection (EC) of barbituric acid (BA) and 2-thiobarbituric acid (TA) has been described. Under optimum condition, BA and TA were separated satisfactorily, and a response of high sensitivity and stability was obtained at a detection potential of 1.25 V versus Ag/AgCl. Optimized end-column detection provides detection limit as low as 0.5 and 0.1 μM for BA and TA, respectively. The calibration graph was linear over three orders of magnitude. The relative standard deviations (n=10) of peak currents and migration times obtained for both BA and TA were 3.4, 3.7, and 1.7, 1.2%, respectively. The proposed method has been applied to analyze water sample with satisfactory results.     

Separation of hyaluronic acid by ultrahigh-voltage capillary gel electrophoresis

Hyaluronic acid was separated using 95 kV applied potential in a polyacrylamide gel-filled capillary. The results of this separation were compared to those obtained using a capillary electrophoresis instrument operated at a more conventional potential of 15 kV. For lower-molecular-weight oligomers, the separation efficiency was found to improve by about tenfold, and the resolution by about threefold. However, the improvement in resolution declined as the polymer molecular weight increased.     

Analysis of Sarcandra glabra and its medicinal preparations by capillary electrophoresis

A simple, rapid, selective and reproducible capillary electrophoresis (CE) method was firstly developed for the identification and determination of isofraxidin and fumaric acid in a traditional Chinese herb Sarcandra glabra and its medicinal preparations. The buffer solution used in this method was 7.5 mM NaH₂PO₄ and 7.5 mM borax solution adjusted to pH 8.60. The linear calibration range was 1.25-800 μg ml⁻¹ (r=0.9997) for isofraxidin and 10-800 μg ml⁻¹ (r=0.9992) for fumaric acid, respectively. Under the optimum conditions, the relative standard deviation (R.S.D.) values of the migration time and the peak area were 0.47, 3.45% for isofraxidin and 0.83, 3.24% for fumaric acid, respectively. The recoveries ranged between 95.4-103.8% for isofraxidin and 97.1-104.7% for fumaric acid, respectively. The contents of isofraxidin and fumaric acid in Sarcandra glabra and two kinds of Sarcandra glabra-containing Chinese medicinal preparations were successfully determined within 8 min.     

Determination of chlorogenic acid and rutin in cigarettes by an improved capillary electrophoresis indirect chemiluminescence system

An improved capillary electrophoresis indirect chemiluminescence system was employed for the determination of chlorogenic acid and rutin in cigarette samples. After being separated by capillary electrophoresis, the analyte zones were determined by indirect chemiluminescence of luminol-potassium hexacyanoferrate. In this system, luminol was added into running buffer solution and introduced at the head of separation capillary, and potassium hexacyanoferrate was introduced at the end of the capillary. A high potential buffer reservoir was constructed from a running buffer cell and an electrode buffer one, which were jointed with a frit, in order to avoid luminol electrolysis in high potential reservoir and the excursion of chemiluminescence baseline. A low potential flow reservoir was used to prevent electrode buffer solution from the contamination of chemiluminescence waste. Therefore, the proposed capillary electrophoresis-chemiluminescence system can avoid the electrolysis of chemiluminescence reagent, retain the stability of chemiluminescence baseline and prolong the working time of running and electrode buffer solutions. In addition, the matrix of cigarette sample solutions has also an inhibitory effect on the chemiluminescence intensity in the indirect detection, whereas the influence was not observed in the separation of standard solutions. After the correction of matrix inhibition and the calibration with standard addition method, chlorogenic acid and rutin were determined in four cigarette samples by the improved capillary electrophoresis-chemiluminescence system.