A simple capillary electrophoresis with electrochemical detection method for determination of the hydrolysis rate constant of chlorogenic acid

A method based on the kinetics stability study on hydrolysis of chlorogenic acid by capillary zone electrophoresis with electrochemical detection (CE-ED) has been developed in this paper. Both cyclic and hydrodynamic voltammograms of chlorogenic acid and its hydrolysis product caffeic acid have been investigated. The conditions for separation of chlorogenic acid and caffeic acid, such as the buffer pH and concentration, the separation voltage, and the injection time have been optimized. Under the optimum CE running conditions, the effects of reaction temperature and pH values of the hydrolysis solutions on the hydrolysis rate constants were further studied. The hydrolysis rate constants of chlorogenic acid were obtained from the concentration change of hydrolysis during the process of hydrolysis. Based on the fact, a simple and economical method for the determination of the hydrolysis rate constant and activation energy of hydrolysis reaction has been developed.     

Development of a capillary electrophoresis method for the enantioselective estimation of primaquine in pharmaceutical formulations

A capillary electrophoresis (CE) method has been developed that allows the separation and estimation of primaquine enantiomers using hydroxypropyl-gamma-cyclodextrin (HP-gamma -CD) as a chiral selector. The influence of chemical and instrumental parameters on the separation, such as type and concentration of CD, buffer concentration, buffer pH, applied voltage, capillary temperature, and injection time, were investigated. Good separation of the racemic mixture of primaquine was achieved using a fused-silica capillary (52.5 cm effective length x 50 microm id) and a background electrolyte composed of tris-phosphate buffer solution (50 mM, pH 2.5) containing 15 mM HP-gamma-CD as a chiral selector. The recommended applied voltage, capillary temperature, and injection time were 15 kV, 25 degrees C, and 6 s, respectively. Within-day and interday reproducibility of peak area and migration time gave relative standard deviation values ranging from 1.05-3.30%. Good recoveries (range of 96.8-104.9%) were obtained from the determination of placebos that were spiked with 0.25-1.00 mg/L primaquine. The proposed CE method was successfully applied to the assay of primaquine diphosphate in pharmaceutical formulations (tablets).     

肝糖选择剂-毛细管电泳手性拆分盐酸度洛西汀对映体及分离机制

以肝糖为毛细管电泳手性选择剂,对盐酸度洛西汀对映体的分离进行研究,建立了拆分方法.考察了手性选择剂浓度、运行缓冲液的离子强度、pH值及分离电压对手性分离的影响.在3.0% (m/V)肝糖、50 mmol/L Tris-H3PO4(pH 3.0)的运行缓冲液中,分离电压25 kV时,盐酸度洛西汀两对映体分离度达1.84.对分离机制进行了初步探讨.     

Application of ionic liquid as additive in determination of three β‐agonists by capillary electrophoresis with amperometric detection

CE coupled with amperometric detection method was developed using ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMImBF₄) as additive for the simultaneous detection of clenbuterol (CLB), terbutaline (TER), and ractopamine (RAC) in feed. The effects of detection potential, concentration of EMImBF₄, pH, and concentration of the running buffer, separation voltage as well as injection time on the separation and detection of these three β‐agonists were investigated in detail. Under the optimum conditions: the detection potential at 1.05 V, 50 mmol/L Tris‐HAc at pH 8.0 with 0.6% (v/v) EMImBF₄, electrokinetic injection 6 s at 16 kV and separation voltage at 16 kV, a baseline separation for these three analytes could be achieved within 11 min. Introduction of EMImBF₄ into the running buffer resulted in significant improvement in separation selectivity and enhancement in peak currents for those β‐agonists, especially for TER and RAC, which could not be separated in the running buffer without additive. The method exhibited wide linear range with LOD (S/N = 3) of 2, 1, and 2 nmol/L for CLB, TER, and RAC, respectively. The precision was determined in both intraday (n = 5) and interday (n = 3) assays, and the RSDs for both migration time and peak current were less than 6%. The proposed method was also applied to analyze β‐agonists in feed sample.     

Determination of metolcarb in food by capillary electrophoresis immunoassay with a laser-induced fluorescence detector

A capillary electrophoresis immunoassay (CEIA) was developed for the determination of trace metolcarb (MTMC) in food. The method was based on the competitive reactions between fluorescently labeled MTMC tracer and free MTMC with a limited amount of anti-MTMC antibody and the separation and determination by CE with LIF detector. A fluorescent reagent, FITC was labeled on MTMC to construct an immunofluorescent probe. CEIA experimental parameters such as the pH value and concentration of the running buffer and separation voltage as well as incubation time were systematically investigated. Under the optimized conditions, fluorescently labeled antigen and antibody bound could be well separated within 3 min using Na?B?O?/NaH?PO? buffer (20:10 mmol/L, pH 9.0) for background electrolyte, 20 kV for the separation voltage, and 20°C for the column temperature. The linear range of the method was 0.25-50.0 μg/L with LOD 0.07 μg/L. The RSD for relative migration time and relative fluorescence intensity ratio were 2.90% (intraday) and 4.73% (intraday), respectively. The proposed method has been applied to determine the residue of MTMC in food samples with the satisfactory recovery.     

Fast Determination of Clenbuterol and Salbutamol in Feed and Meat Products Based on Miniaturized Capillary Electrophoresis with Amperometric Detection

The fast separation capability of a novel miniaturized capillary electrophoresis with an amperometric detection (μCE‐AD) system was demonstrated by determining clenbuterol and salbutamol in real samples. The effects of several factors such as the acidity and concentration of the running buffer, the separation voltage, the applied potential and the injection time on CE‐AD were examined and optimized. Under the optimum conditions, the two β‐agonists could be baseline separated within 60 s at a separation voltage of 2 kV in a 90 mmol/L H₃BO₃‐Na₂B₄O₇ running buffer (pH 7.4), which was not interfered by ascorbic acid and uric acid. Highly linear response was obtained for above compounds over three orders of magnitude with detection limits ranging from 1.20×10^?7 to 6.50×10^?8 mol/L (S/N=3). This method was successfully used in the analysis of feed and meat products with relatively simple extraction procedures.     

基于细菌纤维素的毛细管电泳法同时测定果蔬中3种苯并咪唑类杀菌剂

建立了高效毛细管电泳同时测定果蔬中3种常见的苯并咪唑类杀菌剂(甲基硫菌灵、多菌灵和苯菌灵)的分析方法。以细菌纤维素(BC)为电泳缓冲液添加剂来提高毛细管电泳的分离能力。系统考察了检测波长、缓冲液离子强度、缓冲液pH、分离电压及BC添加量对3种苯并咪唑类杀菌剂分离效果的影响。最终的优化条件:H3BO3/Na2B4O7缓冲液(4 mmol/L,pH 9.0);BC添加质量分数0.3%;运行电压15 kV;分离柱温25℃;检测波长275 nm。3种苯并咪唑类杀菌剂在8 min之内可实现基线分离及准确定量。结果显示:3种苯并咪唑类杀菌剂在各自线性范围内线性关系良好,相关系数(r2)≥0.997;检出限为5.0~10.0μg/L;保留时间及峰面积的日间相对标准偏差(n=5)分别为0.82%~1.0%和2.4%~2.9%。该法用于葡萄、番茄及黄瓜中3种苯并咪唑类杀菌剂的测定,加标回收率为93.5%~103.0%,RSD≤8.0%。该法可作为果蔬中甲基硫菌灵、多菌灵和苯菌灵同时检测的有效手段。     

高效毛细管电泳安培法测定肉苁蓉中松果菊苷的含量

采用毛细管电泳安培法建立了肉苁蓉中松果菊苷含量的检测方法,探讨了缓冲溶液种类、工作电位、分离电压、进样时间等对分离和检测的影响.在15 mmol/L硼砂缓冲溶液(pH 9.5),25 kV电压,0.6 V工作电位的条件下,松果菊苷的质量浓度在0.5～50.0 mg/L范围内与峰面积呈良好线性,相关系数为0.9994,检...     

毛细管电泳-电致化学发光法测定兔血浆中的羟考酮

基于稀土Eu(Ⅲ)掺杂的类普鲁士蓝膜修饰的铂电极为工作电极,建立了测定羟考酮的毛细管电泳-电致化学发光分析方法。考察了检测电位、运行缓冲溶液的酸度及浓度、分离电压、进样条件等对电泳分离效果及检测灵敏度的影响。在最佳的实验条件下,羟考酮可在4 min内得到分离,其ECL强度值与羟考酮的质量浓度在7.0×10-2～7.0μg/mL和7.0～70.0μg/mL范围内呈良好的线性关系,检出限为4.2×10-2μg/mL(3σ),峰高和迁移时间的相对偏差分别为3.6%和0.48%(n=6)。方法用于兔血浆中羟考酮含量的检测,加标回收率在99.7%～101.0%之间。     

Capillary electrophoresis combining three-step multiplex polymerase chain reactions for diagnosing α-thalassemia

Capillary electrophoresis (CE) is the most useful tool for DNA separation because of its high resolution. In this study, different kinds of polymers were used to evaluate the separation efficiency by analyzing a 200-bp DNA ladder. Under optimized CE conditions, the CE separation was performed by DB-17 capillary. The running buffer was a 1× TBE buffer containing 0.6% w/v poly(ethylene oxide) (PEO) (Mw: 8,000,000) and 1?μM YO-PRO-1; applied voltage was -10?kV (detector at anode side) and the separation temperature was 25°C. Under these optimal conditions, 15 DNA fragments with sizes ranging from 0.2 to 3.0?kb were resolved within 11.5?min and the RSD of migration time were less than 0.55% (n=3). This method, combined with three-step multiplex PCR, was applied to detect five α-thalassemia deletions, including -α(3.7) , -α(4.2) , - -(SEA) , - -(FIL) and - -(THAI) . A total of 21 patients diagnosed with α-thalassemia were analyzed using this developed method and all results agreed with those already obtained by gel electrophoresis.     

Rapid and sensitive analysis of three polyphenols in tobacco by CE using homemade C(4) D with a mini detection cell

A rapid, sensitive, and practical CE with C(4) D detection was developed for the analysis of three polyphenols (rutin, scopoletin, and chlorogenic acid) in tobacco samples. The constructed mini detection cell (12 mm × 10 mm × 10 mm) of C(4) D featured with small inner cell volume (～2 nL), smaller noise (<0.9 mV), repeatability, high strength and durableness. Three polyphenols were ultrasonically extracted with methanol-water (70:30, v/v) solution following SPE cleanup. The CE method was optimized with the running buffer of 150 mmol L(-1) 2-amino-2-methyl-1-propanol (pH 11.2), and the applied separation voltage of +20 kV over a capillary of 50 μm id × 375 μm od × 50 cm (38 cm to the C(4) D window, 41.5 cm to the UV detector window), which gave a baseline separation of three polyphenols within ca. 6 min. The method provided the limits of quantification (S/N = 10) at about 0.08-0.15 μg g(-1) for three polyphenols, whereas the overall recoveries ranged from 82% to 88%. The proposed method has been successfully applied to measure three polyphenols in the actual tobacco samples, and their contents were calculated and evaluated.     

Determination of active constituents in Lonicera confusa DC. by capillary electrophoresis with amperometric detection

A method based on capillary electrophoresis with amperometric detection has been developed for the determination of luteolin, chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeic acid in the dried flower buds, leaves and stems (three medicinal parts) of Lonicera confusa DC., respectively. The effects of several important factors such as detection potential, the concentration of the running buffer, separation voltage and injection time were investigated to acquire the optimum conditions. The detection electrode was a 300 microm diameter carbon disc electrode at a working potential of + 0.90 V (vs saturated calomel electrode). The four analytes can be well separated within 10 min in a 40 cm-long fused silica capillary at a separation voltage of 12 kV in a 50 mM borate-25 mM phosphate buffer (pH 8.0). The relationship between peak current and analyte concentration was linear over about 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.35 to 0.52 microM for all analytes. The proposed method has been successfully applied to the monitoring of bioactive constituents in the real plant samples with satisfactory assay results.     

Synthesis and application of clindamycin succinate as a novel chiral selector for capillary electrophoresis

A novel chiral selector, clindamycin succinate, was synthesized and first used as a chiral selector in capillary electrophoresis (CE). The chiral resolution ability of this kind of clindamycin derivation was studied by CE using some racemic drugs as model analytes. From the experimental results, it was found that both resolution and selectivity of the selector were dependent on the following parameters: concentration of chiral selectors, pH of the running buffer, temperature of the capillary column, applied voltage and organic modifier used. The results show that the chiral selector possesses high resolution toward some racemic drugs, including ofloxacin, chlorphenamine, tryptophan, propranolol, sotalol and metoprolol. Excellent chiral resolution of these tested drugs was achieved under the optimal conditions of 50 mM clindamycin succinate, 10% MeOH v/v, 50 mM Tris buffer, pH 4.0, at 22 kV and 20 °C within 25 min.     

Separation and determination of isoflavones in red clover by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography (MECC) method has been developed for the determination of the four isoflavones, i.e. biochanin A, formononetin, genstein and daidzein in red clover (Trifolium Pratense L.). The effect of running buffer pH and concentration were investigated. An electrolyte composed of 30 mm borate, 20 mm sodium dodecyl sulfate (SDS) and 4 mg/mL HP-beta-CD containing 5% (v/v) ethanol at pH 10.1 provides a satisfactory separation for all the analytes. The applied voltage was 25 kV, and the capillary temperature was kept constant at 25 degrees C with a UV detection at 254 nm. The relative standard deviations (RSD) of the migration time and peak area were less than 1.73 and 3.94% (intra-day), and 2.29 and 4.38% (inter-day), respectively, under the optimized separation conditions. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The contents of the four compounds in red clover were successfully determined with satisfactory repeatability and recovery.     

Capillary electrophoresis of anthraquinones from Cassia siamea

The separation and determination of two anthraquinones, emodin and chrysophanol, and two bianthraquinones, cassiamin A and cassiamin B, were achieved by capillary electrophoresis (CE). The running electrolyte used in this method was 0.05 M hydroxypropyl-gamma-cyclodextrin in 0.1 M borate buffer (pH 9) containing 10% acetonitrile, with an applied voltage of 20 kV. Application of this technique in the determination of the main bianthraquinones, cassiamin A and cassiamin B, of Cassia siamea is demonstrated in this paper.     

毛细管区带电泳法分析绿茶中的痕量成份

采用毛细管电泳/安培检测法(CE/AD)同时分离测定了绿茶中的芦丁、没食子酸、槲皮素、绿原酸等生物活性成分的含量, 考察了运行缓冲液酸度、浓度、分离电压、氧化电位和进样时间等实验参数对分离、检测的影响。在最优化条件下, 以300 μm碳圆盘电极为检测电极, 检测电位为+ 950 mV (vs. SCE) , 60 mmol/L硼酸盐运行缓冲液(pH 8.7)中, 上述各组分在20 min内可实现基线分离。各组分浓度与峰电流在3个数量级范围内呈良好线性, 检出限(S/N=3)在1.0×10^-7到1.0×10^-4g^.mL^-1范围,四种标样7次平行进样的相对标准偏差(RSD)小于3.0 %。该方法已成功地应用于绿茶中生物活性成分的测定, 结果令人满意。     

Gold nanomaterials based pseudostationary phases in capillary electrophoresis: A brand‐new attempt at chondroitin sulfate isomers separation

In this work, a CE method with bare gold nanorods (GNRs) based pseudostationary phase was developed and applied for the separation of chondroitin sulfate (CS) isomers, CS, and dermatan sulfate (DS). The separation efficiency was investigated by varying the experimental parameters such as concentration and pH of the BGE, separation voltage, internal diameter of capillary, different size, and morphology of gold nanomaterials. Results showed that different size and morphology of gold nanomaterials had different effects on the separation of CS and DS. The best separation of CS and DS was achieved in the BGE composed of aqueous 150 mmol/L (mM) ethylenediamine + 20 mM sodium dihydrogen phosphate + 30% v/v GNRs, pH 4.5, at the separation voltage of ?10 kV. Capillary was 59.2 cm in length (effective length 49 cm), 50 μm id capillary thermostated at 25°C. CE with bare GNRs used as pseudostationary phase was shown to be a suitable technique for the separation of CS and DS mixtures with wider peaks. RSD of migration time and peak area of CS and DS were 0.13, 0.14 and 0.86, 1.07%, respectively.     

毛细管电泳-激光诱导荧光用于中药制剂中氨基酸成分的分析

建立了一种用于测定中药制剂中氨基酸成分的毛细管电泳-荧光检测方法. 用含有α-环糊精(α-CD)的硼砂缓冲溶液为背景电解质, 经异硫氰酸荧光素(FITC)衍生的5种氨基酸在50 min内可以得到很好的分离和测定. 考查了各个分离参数对分离的影响, 得到的优化条件为: 含45 mmol/L的α-环糊精的80 mmol/L硼砂缓冲溶液(pH值9.2)作为背景电解质, 分离电压20 kV; 柱温22 ℃. 衍生试剂FITC与单个氨基酸的化学计量比为4∶1时, 能够获得稳定荧光强度的氨基酸衍生物. 在优化条件下, 各氨基酸成分在73.5～2900 nmol/L 的浓度范围内呈良好的线性关系(相关系数r2为0.9906～0.9998). 保留时间和峰面积的相对标准偏差分别为0.8%～3.0%和0.7%～5.7%, 检测限(3倍信噪比)为3.5～35 nmol/L. 该方法准确可靠, 可用于质量控制为目的的中药制剂中氨基酸成分的定量测定.     

Capillary electrophoresis coupled with in‐column fiber‐optic laser‐induced fluorescence detection for the rapid separation of neodymium

In this study, in‐column fiber‐optic (ICFO) laser‐induced fluorescence (LIF) detection technique is coupled with capillary electrophoresis (CE) for the rapid separation of neodymium for the first time. The effects of buffer concentration, buffer pH, and separation voltage on the CE behaviors, including electrophoretic efficiency and detection sensitivity, are investigated in detail. Under the optimal condition determined in this study (15 mM borate buffer, pH 10.50, separation voltage 24 kV), neodymium could be separated effectively from the neighboring lanthanides (praseodymium and samarium) within several minutes, and the limit of detection for neodymium is estimated to be at the ppt level. The ICFO‐LIF‐CE system assembled in this study exhibits unique performance characteristics such as low cost and flexibility. Meanwhile, the separation efficiency and detection sensitivity of the assembled CE system are comparable to or somewhat better than those obtained in the previous traditional CE systems, indicating the potential of the assembled CE system for practical applications in the fields of spent nuclear fuel analysis, nuclear waste disposal/treatment, and nuclear forensics.