毛细管电泳法测定甘草中的甘草素和异甘草素

采用高效毛细管电泳分离并测定了甘草草药和复方甘草合剂中的甘草素和异甘草素的含量。研究了实验参数对分离、检测的影响,得到了优化的实验条件。在50mmol／L硼砂缓冲溶液(pH＝9.0)中,甘草素和异甘草素在7min内得到良好的分离。甘草素和异甘草素分别在1.0×10-4～5.0×10-7g／mL、5.0×10-4～1.0×10-6g／mL范围内与电泳峰高呈良好的线性关系,检出限分别为5.0×10-8和2.0×10-7g／mL,已成功地应用于实际样品的测定。     

多壁碳纳米管对甘草中3种有效成分的选择性吸附

考察了多壁碳纳米管(MWNTs)对3种甘草有效成分异甘草苷、甘草苷和甘草酸的吸附性能。 分别用紫外分光光度法和HPLC法测定了吸附前后溶液中异甘草苷、甘草苷、甘草酸的含量,考察了静态吸附实验时间、料液起始浓度、溶液体积和pH值对各成分吸附的影响。 结果显示,MWNTs对甘草中3种主要有效成分的吸附量明显不同,对异甘草苷的吸附远大于甘草苷和甘草酸,并且不存在竞争吸附,具有明显的选择性吸附特点。     

胶束毛细管电动色谱法在线富集联用技术灵敏检测乳制品和饲料样品中的三聚氰胺

建立了胶束毛细管电泳(MEKC)在线富集技术灵敏检测三聚氰胺的方法,采用场放大进样(FASS)联用胶束扫集(Sweep)测定多种样品中的三聚氰胺.试样用乙腈反复提取3次,在优化实验条件下,三聚氰胺的检测灵敏度提高了约1000倍,检出限由原来的2 mg/L降到1.8 μg/L(S/N=3).本方法用于配方奶粉和动物饲料中...     

固相萃取/液相色谱-质谱/质谱法测定山银花中5种主要黄酮苷元的含量

该文通过含有盐酸的乙醇溶液回流水解并提取,HLB固相萃取柱净化,液相色谱-质谱/质谱法检测,建立了山银花中槲皮素、木犀草素、山萘酚、芹菜素和黄芩素5种黄酮苷元含量的测定方法。实验以芦丁、木犀草苷、紫云英苷、野漆树苷和黄芩苷5种黄酮苷为代表开展研究,山银花样品经50%的乙醇溶液(含10%浓盐酸)回流2 h水解黄酮苷,同时对黄酮苷元进行提取,HLB固相萃取柱净化,采用Mightysil RP-18色谱柱分离,液相色谱-质谱/质谱法检测(电喷雾离子源、多反应监测模式、负离子扫描),外标法定量测定水解后的5种黄酮苷元含量。方法的定量下限(S/N=10)为0.005 g/kg(槲皮素),0.01 g/kg(木犀草素和芹菜素)和0.05 g/kg(山萘酚和黄芩素)。在0~1.0 g/kg范围内,5种黄酮苷元的线性相关系数均大于0.995;在山银花样品中对待测物进行3种加标水平的回收实验(加标水平相当于水解后槲皮素和木犀草素含量为:0.10、0.20、0.40 g/kg,山萘酚、芹菜素和黄芩素含量为:0.05、0.10、0.20 g/kg),方法的平均回收率70.4%~104%;相对标准偏差为4.0%~12%。该方法实现了山银花中多种主要黄酮苷元含量的同时测定,且对研究山银花药效及与黄酮类化合物的关系具有重要意义。     

甘草苷在玻碳电极上的电化学行为及其测定

在pH 3.00的B-R缓冲溶液中,采用差分脉冲伏安法(DPV)、线性扫描伏安法(LSV)和循环伏安法(CV)研究了甘草苷在玻碳电极上的电化学行为, 建立了测定甘草苷的DPV法。实验结果表明,甘草苷于1.16 V (vs.Ag/AgCl)处产生一个氧化峰,峰电流和甘草苷的浓度在2.00×10-6~3.50×10-5 mol/L范围内呈良好的线性关系,检出限为8.25×10-7 mol/L。该法用于实际样品甘草、胃康灵和逍遥丸中黄酮含量的测定(以甘草苷为对照品),平均回收率分别为97.1%、98.9%和102.0%。此外对电极反应机理作了初步探讨。     

HPLC-DAD-ESI/MS~n-DPPH在线筛选与鉴别丹参和康定鼠尾草中抗氧化活性成分

本研究建立了在线高效液相色谱-质谱-二苯基三硝基苯肼(HPLC-DAD-ESI/MSn-DPPH)快速筛选和鉴别丹参和康定鼠尾草中抗氧化活性成分和含量的方法。经液相色谱、质谱和文献报道综合分析鉴定出丹参和康定鼠尾草中的3种抗氧化活性化合物,分别为咖啡酸、异迷迭香酸苷和迷迭香酸。比较了热回流、超声辅助提取和快速溶剂萃取的提取效果,并对色谱条件进行优化。在优化条件下,这3种化合物均可有效分离,并在1.7~35.3μg/m L范围内线性关系良好,相关系数为0.999 5~0.999 8,检出限为0.05~1.85μg/m L,定量下限为0.18~6.16μg/m L,平均回收率为96.6%~97.2%,相对标准偏差为1.1%~1.3%。运用该方法测定丹参和鼠尾草样品中这3个化合物的含量分别为:咖啡酸0.303,0.254 mg/g;异迷迭香酸苷1.019,1.401 mg/g;迷迭香酸17.279,8.104 mg/g。本方法简便、快速、准确、重现性好,适用于从复杂天然产物中快速筛选与鉴别抗氧化活性成分。     

反相高效液相色谱法分离测定烟草中的多酚类化合物

对植物中9种多酚类化合物的色谱分离条件进行了优化,分别探讨了流动相组成、流动相中醋酸浓度、醋酸溶液与甲醇的比例对保留时间的影响,确定了梯度分离条件,并对9种天然多酚类化合物进行了定量分析。该方法的检测限为13.26~59.29 mg/kg (S/N=3)。在3.0～100.0 mg/L 范围内呈良好的线性关系,相关系数r2为 0.9979~0.9999。9种待测化合物的加标回收率为96.8%~108%,相对标准偏差(RSD)小于3.8% (n=3)。用80%甲醇超声提取烟草样品,并通过优化的色谱条件对其进行分析,测定了实际烟草样品中芸香苷和绿原酸的含量。结果表明,该方法具有一定的实用价值。     

聚焦微波辅助双水相萃取/高效液相色谱法测定农吉利中牡荆素与异牡荆素

以乙醇-硫酸铵双水相体系为萃取溶剂,采用聚焦微波辅助萃取法萃取农吉利中的牡荆素和异牡荆素,HPLC测定,建立了微波辅助双水相萃取(FMAATPE)/HPLC方法测定牡荆素和异牡荆素含量的分析方法。利用单因素试验和正交试验设计方法优化了乙醇质量分数、微波功率、料液比、萃取时间等萃取条件以及色谱分析条件。萃取优化条件为:双水相的组成:35%乙醇-16%硫酸铵,药材颗粒度:80目,料液比:1∶50,微波功率:140 W,萃取时间:20 min。以乙腈-0.5%磷酸(14∶86)为流动相在340 nm检测可较好地分离目标组分。将该方法用于农吉利药材中牡荆素和异牡荆素的萃取测定,可获得满意结果,其回收率为96.9%~103.8%,RSD为1.9%~2.6%。     

在线富集-胶束电动毛细管色谱用于烷基酚类物质的检测

以胶束电动毛细管色谱(Micellar electrokinetic capillary chromatography,MEKC)分离邻仲丁基苯酚(os BP)、双酚A(BPA)、四溴双酚A(TBBPA)、辛基酚(OP)和壬基酚(NP)。采用反向极性堆积模式(Reversed electrode polarity stacking mode,REPSM)建立了在线富集5种烷基酚类物质的简便、有效方法。与常规MEKC方法相比,REPSM方法使5种烷基酚类物质的灵敏度提高了20~285倍。考察了常规MEKC的分离条件,并对影响富集过程的一些因素进行了研究,同时对富集方法的重现性和检出限进行了考察。结果表明,REPSM对5种烷基酚类物质的检出限(S/N=3)为0.027~0.64μmol/L。该方法已成功应用于食品塑料盒中烷基酚类物质的测定,加标回收率为86.0%~103%。     

响应面法优化-微波辅助萃取-高效液相色谱法测定农吉利中牡荆素和异牡荆素

应用响应面法优化了乙醇微波辅助萃取农吉利中牡荆素和异牡荆素的条件,用高效液相色谱法测定提取液中牡荆素和异牡荆素的含量。用单因素试验选取了萃取温度、液料比及萃取时间等3项条件,并在此基础上,用中心组合试验设计,采用三因素三水平数学模型和响应面法分析进行优化,确定了最优提取条件为:①萃取温度152℃;②液料比为44:1;③萃取时间6.6 min。在此条件下牡荆素和异牡荆素的提取率分别为253.3,236.9μg·g^-1,与理论值相近。样品加标回收率分别在97.0%～104%和96.0%～102%之间。     

Simultaneous determination of five flavonoids in licorice using pressurized liquid extraction and capillary electrochromatography coupled with peak suppression diode array detection

Pressurized liquid extraction (PLE) and capillary electrochromatography (CEC) methods were developed for the simultaneous determination of five flavonoids, namely liquiritin, isoliquiritin, ononin, liquiritigenin and isoliquiritigenin, in licorice using baicalein as internal standard (IS). Peak suppression technique was used for the quantification of ononin because of its poor resolution with isoliquiritin. The analysis was performed on a Hypersil C₁₈ capillary (3 μm, 100 μm/25 cm) with a mixture of 10 mM phosphate buffer (pH 3.0)/ACN (65:35, v/v) as mobile phase running at 25 kV and 30 °C. The detection wavelengths were set at 275 nm (without reference wavelength for liquiritin and liquiritigenin), 360 nm (without reference wavelength for isoliquiritin and isoliquiritigenin) and 254 nm (with reference wavelength of 405 nm for ononin). All calibration curves showed good linearity (R² > 0.9993) within the test ranges. The LOD and LOQ were lower than 2.1 and 8.3 μg/mL, respectively. The RSDs of intra- and interday for relative peak areas of five analytes to IS were less than 3.8 and 4.7%, respectively, and the recoveries were 98.2–103.8%. The validated method was successfully applied to the quantitative analysis of five flavonoids in licorice, which is helpful to its quality control.     

Simultaneous quantification of multiple licorice flavonoids in rat plasma

Flavonoids are important naturally occurring polyphenols with antioxidant properties. In this study, we report the development of a liquid chromatography tandem mass spectrometry (LC-MS/MS)-based method capable of simultaneously quantifying multiple active licorice flavonoids (including liquiritin apioside, liquiritin, liquiritigenin, isoliquiritin apioside, isoliquiritin, and isoliquiritigenin) in plasma. Electrospray ionization was used to efficiently generate precursor deprotonated molecules of all the analytes and the [M-H]- ions were used to produce characteristic product ions for MS/MS analysis. We found that inclusion of a very low concentration of HCOONH4 (0.01 per thousand) in the LC mobile phase dramatically improved the detection limit for the tested flavonoids and decreased the interference by matrix effects, which have been referred to as "LC-electrolyte effects." Liquid-liquid extraction with ethyl acetate was effective for isolation of all the analytes and resulted in the lowest matrix effects of several tested sample cleanup methods. This bioanalytical method showed good linearity between 0.32 ng/mL and 1 microg/mL analyte in 50-microL plasma samples. The accuracy and precision at different analyte concentrations varied from 85 to 110% and from 0.8 to 8.8%, respectively. Finally, we demonstrated the applicability of this method in a pilot pharmacokinetic study of rats receiving an oral dose of Xiaochaihu-tang, an important Chinese herbal remedy for chronic hepatitis. The use of a low concentration of HCOONH4 in the LC mobile phase could be used to improve LC-mass spectroscopy- or LC-MS/MS-based methods.     

Determination of liquiritigenin and isoliquiritigenin in Glycyrrhiza uralensis and its medicinal preparations by capillary electrophoresis with electrochemical detection

A simple, reliable, reproducible and sensitive method, based on capillary electrophoresis with electrochemical detection (ED), for the determination of liquiritigenin and isoliquiritigenin in Glycyrrhiza uralensis and its medicinal preparations was described. Operated in a wall-jet configuration, a 300 microm diameter carbon-disk electrode was used as the working electrode, which exhibits good responses at + 1000 mV (versus SCE) for the two analytes. Under the optimum conditions, the analytes were base-line separated within 8 min, and excellent linearity was obtained in the concentration range from 5.0 x 10(-4) to 1.0 x 10(-6) mol/l. The detection limit (S/N = 3) was 4.7 x 10(-7) and 2.9 x 10(-7) mol/l for liquiritigenin and isoliquiritigenin, respectively. This work provides a useful method for the analysis of traditional Chinese medicines.     

On-line concentration by field-enhanced sample injection with reverse migrating micelles in micellar electrokinetic capillary chromatography for the analysis of flavonoids in Epimedium brevicornum Maxim

A simple and sensitive micellar electrokinetic capillary chromatography (MEKC) method was developed for the separation and determination of six flavonoids in Epimedium brevicornum Maxim. Field-enhanced sample injection with reverse migrating micelles (FESI-RMM) was used for on-line concentration of the flavonoids. An electrolyte containing 20 mM H3PO4, 100 mM SDS, 20% acetonitrile and 2% 2-propanol (pH 2.0) was chosen as the electrophoretic buffer. By optimizing the stacking conditions, about 40-360-fold improvement in the detection sensitivity was obtained for the flavonoids.     

Simultaneous quantification of catechin,epicatechin, liquiritin,isoliquiritin, liquiritigenin,isoliquiritigenin, piperine and glycyrrhetinic acid in rat plasma by HPLC‐MS/MS: application to a pharmacokinetic study of Longhu Rendan pills

A sensitive, specific, accurate HPLC‐MS/MS method was developed and validated for the simultaneous quantification of catechin, epicatechin, liquiritin, isoliquiritin, liquiritigenin, isoliquiritigenin, piperine and glycyrrhetinic acid from Longhu Rendan pills in rat plasma. Chromatographic separation was performed with a Hypersil Gold C₁₈ column using a gradient of methanol and 0.01% acetic acid containing 0.2 mm ammonium acetate as mobile phase. The analytes were quantified on a triple quadrupole mass spectrometer, operating in selected reaction monitoring mode and switching the electrospray ion source polarity between positive and negative modes in a single run. The calibration curves of catechin, epicatechin, liquiritin, isoliquiritin, liquiritigenin, isoliquiritigenin, piperine and glycyrrhetinic acid were linear over the concentration ranges of 5–2000, 5–2000, 0.5–200, 0.5–200, 0.25–100, 0.25–100, 0.025–10 and 0.50–200 ng mL^?1, respectively. The intra‐ and inter‐assay precisions and accuracies were <11.6 and 91.9–108.2%, respectively, for all analytes. Matrix effects for all analytes were between 88.2 and 114.2%. Stability testing showed that all analytes were stable in plasma at 24 °C for 3 h, at 4 °C for 24 h, after three freeze–thaw cycles, and at ?80 °C for 15 days. The method was successfully applied to an in vivo study evaluating the pharmacokinetics of multiple nonvolatile compounds following intragastric administration of Longhu Rendan pills to rats. Copyright © 2016 John Wiley & Sons, Ltd.     

Isoliquiritigenin extracted from licorice <Emphasis Type="Italic">Glycyrrhiza uralensis</Emphasis> roots by a facile conversion technique

Isoliquiritigenin (1), one of the major constituents of licorice, is a natural pigment with a simple chalcone structure 4,2',4'-trihydroxychalcone. This study was performed to determine whether liquiritin, isoliquiritin, and liquiritigenin can be converted into isoliquiritigenin using alkaline conversion after acid hydrolysis. An orthogonal L₉ (3)⁴ test design was used in the extraction mode and used for optimization of the extract conditions, and the yield from the conventional procedure and from the optimum procedure to extract 1 was compared. The results demonstrated that the yield of the novel procedure was increased about 27 times compared with the conventional procedure, which indicated that the novel procedure is powerful in separating and purifying isoliquiritigenin.     

One step isolation and purification of liquiritigenin and isoliquiritigenin from Glycyrrhiza uralensis Risch. using high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale has been successfully applied to the separation of bioactive flavonoid compounds, liquiritigenin and isoliquiritigenin in one step from the crude extract of Glycyrrhiza uralensis Risch. The HSCCC was performed using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-acetonitrile-water (2:2:1:0.6:2, v/v). Yields of liquiritigenin (98.9% purity) and isoliquiritigenin (98.3% purity) obtained were 0.52% and 0.32%. Chemical structures of the purified liquiritigenin and isoliquiritigenin were identified by electrospray ionization-MS (ESI-MS) and NMR analysis.     

Concentration and determination of cotinine in serum by cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC), combined with on-line concentration techniques, cation-selective exhaustive injection (CSEI) and sweeping, was developed for the analysis of cotinine, the primary biomarker for exposure to secondhand smoke. Experimental parameters including sample matrix, surfactant concentration, injection length and concentration of high-conductivity buffer, and sample electrokinetic injection time were optimized for electrophoretic enrichment and separation processes. Under the optimal conditions, the detection sensitivity of cotinine was enhanced by about 5000-fold using CSEI-sweeping MEKC compared to normal MEKC. The limit of detection for cotinine was found to be 0.2 ng/mL using ultraviolet absorbance detection. Furthermore, the developed method was successfully applied to the detection of cotinine in mouse serum samples.     

Chemical profiling by LC–MS/MS and HPLC fingerprint combined with chemometrics and simultaneous determination of 16 characteristic ingredients for the quality consistency evaluation of Shaoyao‐Gancao Decoction

In this paper, to evaluate the effect of the region of origin on the quality consistency of Shaoyao‐Gancao Decoction (SGD), the SGD fingerprint was developed for the first time. Chemometric methods including similarity analysis, hierarchical clustering analysis and principal component analysis were employed to study the quality consistency of SGD. Meanwhile, high‐performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight mass spectrometry was applied for comprehensive analysis of SGD and 93 compounds were tentatively characterized. Furthermore, a high‐performance liquid chromatography method with multi‐wavelength switching for simultaneous determination of 16 characteristic ingredients comprising gallic acid, oxypaeniflorin, albiflorin, paeoniflorin, liquiritin apioside, liquiritin, isoliquiritin apioside, galloylpaeoniflorin, 1,2,3,4,6‐penta‐O‐galloyl‐d ‐galactopyranose (PGG), ononin, isoliquiritin, liquiritigenin, benzoylpaeoniflorin, glycyrrhizic acid, isoliquiritigenin and formononetin, was established. All 16 analytes show excellent linearity (R² ≥ 0.9990) with recoveries ranging from 96.58 to 104.61% and limits of detection and quantification of 0.022–0.291 and 0.037–0.635 μg/mL, respectively. Finally, it was successfully applied to determine 15 batches of SGD. The results of our research indicate that different regions of origin have a significant effect on the quality consistency of SGD, and its fingerprint combined with chemometrics and multi‐ingredient determination comprise an efficient and reliable approach for quality consistency evaluation.     

大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法对马来酸氯苯那敏的测定

建立了大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法测定马来酸氯苯那敏片中马来酸氯苯那敏的新方法,并考察了样品中乙腈和NaCl浓度对分离效果的影响.结果表明,以12 mmol/L四硼酸钠-50 mmol/L硼酸- 50 mmol/L十二烷基硫酸钠(SDS)为缓冲液(含10%甲醇,pH9.1),以70%乙腈- 200m...