Separation and determination of seven fluoroquinolones by pressurized capillary electrochromatography

In this paper, pressurized CEC was used for the separation and determination of seven fluoroquinolones (FQs). The effect of different experimental conditions, such as the concentration and pH of the buffer, the organic modifier concentration, the surfactant and ion-paring agents added to the electrolyte, and applied voltage were studied. All the seven FQs were baseline separated using mobile phase containing 27% v/v ACN, 5 mmol/L Na2HPO4 buffer (pH 4.0 adjusted using citric acid), 11 mmol/L SDS, and 0.01% TEA v/v at detection wavelength of 287 nm and at an applied voltage of -10 kV. The calibration curves were linear (r>0.9991) over a concentration range of 1.0-50.0 mg/L for norfloxacin (NFLX); 2.5-50.0 mg/L for fleroxacin (FLX), ciprofloxacin (CPFX), and lomefloxacin (LMX); and 5.0-50.0 mg/L for enoxacin (ENX), ofloxacin (OFLX), and gatifloxacin (GFLX). The detection limits (S/N = 3) for ENX, OFLX, FLX, NFLX, CPFX, LMX, and GFLX were 0.5, 0.8, 0.4, 0.2, 0.4, 0.5, and 1.0 mg/L, respectively. The method is simple, rapid, and reproducible. It was successfully applied to the analysis of fish muscle samples spiked with FQs. Mean recoveries ranged from 81.6 to 97.6%.     

新型亚微米亲水作用色谱的制备及其在加压毛细管电色谱中的应用

采用改良Stöber法合成580 nm亚微米单分散的二氧化硅微球，并以此为基质，通过"巯基-烯"点击化学反应将半胱氨酸成功键合到修饰有乙烯基团的二氧化硅微球表面，合成了一种新型亚微米亲水作用固定相（Cys-VTMS-SiO₂）。采用高压匀浆法制备了新型亚微米亲水色谱填充柱，通过不同乙腈比例、缓冲盐浓度和pH条件下对甲苯、丙烯酰胺和硫脲的分离分析揭示其亲水机理。依托加压毛细管电色谱平台，成功实现了对核苷、酚类、胺类及多肽等亲水性物质的快速有效分离，其有望应用于其他强极性和亲水性化合物的分离分析。     

亲水作用毛细管整体柱的制备及其用于奶制品中三聚氰胺的加压毛细管电色谱分析

以甲基丙烯酸丁酯(BMA)和3-［N,N-二甲基-［2-(2-甲基丙-2-烯酰氧基)乙基］铵］丙烷-1-磺酸内盐(SPE)为单体,制备了新型的亲水作用毛细管整体柱,并通过三聚氰胺在此柱上的保留行为证明其具有亲水性。以加压毛细管电色谱(pCEC)技术为平台,优化了整体柱基于亲水作用分离分析奶制品中三聚氰胺的色谱条件。当流动相中乙腈与10 mmol/L磷酸盐缓冲液的体积比为80:20, pH为3.0,电压为3 kV,检测波长为215 nm时,三聚氰胺能获得很好的分离。方法学考察结果表明,合成的亲水整体柱具有良好的重现性和渗透性,建立的pCEC分析方法的检出限为0.05 mg/L。该方法简单方便,回收率较高,而且流动相中无需添加离子对试剂,适合于奶制品中三聚氰胺的定量测定。     

基于加压毛细管电色谱-激光诱导荧光联用技术研究离子强度对维生素B_2光解反应的影响

基于加压毛细管电色谱-激光诱导荧光检测法建立了分析维生素B2及其荧光性光解产物的方法,并用于研究维生素B2在水溶液和磷酸盐缓冲液中的光解反应速率与离子强度之间的关系。发现在C18毛细管色谱柱,流动相为含0.1%(v/v)三氟乙酸的乙腈水溶液,梯度洗脱,激发波长为488 nm,发射波长为520 nm的条件下,维生素B2及多种荧光性光解产物均得到很好的分离和检测,维生素B2的定量限为5×10-8mol/L。在此基础上研究了维生素B2的光降解反应受光照时间和离子强度等的影响。发现离子强度对维生素B2溶液的光解反应有显著影响,离子强度越大,光解速度越快。并进一步通过动力学计算得到维生素B2在水溶液和磷酸盐缓冲液中光解反应的表观速率常数。该研究为维生素B2的光稳定研究提供了一种高效分离和检测的方法,并为维生素B2的保存及临床使用提供了参考。     

微流蒸发光散射检测器与加压毛细管电色谱联用测定川贝枇杷糖浆中6种有效成分的含量

建立了同时测定川贝枇杷糖浆中6种有效成分(桔梗皂苷D、贝母辛、齐墩果酸、西贝素、贝母甲素和贝母乙素)含量的微流蒸发光散射检测器(μELSD)与加压毛细管电色谱(p CEC)联用检测方法。搭建p CEC-μELSD联用平台,采用C18毛细管色谱柱(EP-150-15-3-C18),流动相为乙腈(A)-10 mmol·L-1甲酸-三乙胺水溶液(p H 11.0)(B),梯度洗脱,柱流速为1.02μL·min-1,施加电压为+10 k V,雾化载气流速为0.4 L·min-1,蒸发温度为40℃。川贝枇杷糖浆中6种有效成分可在10 min内得到分离检测,6种有效成分的线性范围可达4个数量级,检出限均在pg水平,加标回收率为97.9%~103.0%。所建立的p CEC-μELSD联用方法精密度、重复性和稳定性良好,且简便、快速、可靠,可用于川贝枇杷糖浆中6种有效成分的含量测定。     

加压毛细管电色谱法高效分离分析葛根多糖中的单糖

葛根多糖具有抗氧化、抗肿瘤等众多生物活性,对葛根多糖进行单糖组成分析对其活性研究具有重要意义。该研究利用响应面分析法考察了超声辅助提取法中液料比、超声温度、超声时间和超声功率对葛根多糖提取率的交互影响,并拟合数据得到多元二次回归方程。同时建立了柱前衍生加压毛细管电色谱检测糖类的方法,对分离8种中性单糖的色谱条件进行了探索与优化,并将此方法应用于两种葛根实际样品的单糖组成测定。响应面分析结果表明,4个试验因素中,超声温度对两种葛根多糖提取率的影响程度最大,其次为液料比,超声时间和超声功率影响程度较小。结合软件预测分析得到的最佳条件及设备实际情况,确定葛根多糖的最佳提取工艺条件为：超声温度90℃,粉葛多糖液料比20 mL/g,柴葛多糖液料比40 mL/g,超声时间30 min,超声功率180 W。优化后的色谱分离条件为：采用Halo-2.7 μm核壳型C18填料毛细管色谱柱,以乙腈-50 mmol/L pH 4.1的醋酸铵水溶液（18：82,v/v）为流动相,在250 nm波长下检测,施加电压-20 kV。在此条件下可以实现24 min内对葡萄糖等8种中性单糖衍生物的快速分离,相比传统液相色谱方法大大提升了分离检测速度和分离柱效。方法学考察表明此方法具有较好的线性关系和良好的重复性。对实际样品分离鉴定表明,粉葛多糖主要由葡萄糖、甘露糖、鼠李糖和岩藻糖组成,4种单糖物质的量之比为1.00：0.16：0.14：0.07;柴葛多糖主要由葡萄糖和甘露糖组成,2种单糖物质的量之比为1.00：0.70。该研究为单糖化合物快速高效分离检测提供了新方法,并为葛根多糖单糖组成分析提供了参考。     

Two-dimensional strong cation-exchange liquid chromatography/reversed-phase pressurized capillary electrochromatography for separation of complex samples

A 2-D separation platform was constructed using micro strong cation-exchange liquid chromatography (μ-SCXLC) and reversed-phase pressurized capillary electrochromatography (RP-pCEC) for the analysis of complex samples. Samples were fractionated by the first-dimension μ-SCXLC with a linear solvent gradient and then injected into the second-dimension RP-pCEC for further separation. The μ-SCXLC/RP-pCEC 2-D system with three separation mechanisms, namely strong cation-exchange, reversed-phase chromatography and electrophoresis, provided high selectivity, high resolution and high peak capacity compared to one-dimensional chromatographic approaches. Separation effectiveness of this 2-D system was demonstrated by the analysis of different kinds of complex samples, such as traditional Chinese medicine Cortex Phellodendri, bovine serum albumin (BSA) tryptic digest and real serum tryptic digest. A theoretical peak capacity of approximately 1200 was achieved, which proves its promising potential for the separation and analysis of complex samples.     

Separation and determination of six catechins in tea by pressurized capillary electrochromatography

An efficient pressurized capillary electrochromatography (pCEC) method has been successfully developed for the determination of six catechins in tea. The separation was performed on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45?cm, effective length of 20?cm, diameter of 100?μm, ODS packing inside for 3?μm). The mobile phase ratio of organic phase, the concentration of phosphate buffer and sodium heptanesulfonate, separation voltage, and other experimental conditions were investigated and optimized. The mobile phase was 15?mM NaH₂PO₄ and 12?mM sodium heptanesulfonate (pH 3.0)/methanol (64:36) at a flow rate of 0.04?mL/min. Under optimal conditions including applied voltage of ?4?kV and a UV detection wavelength of 230?nm, the six catechins in the tea were well separated. The calibration curves for the analytes had good linearity in the range of 8.02?μg/mL–202.13?μg/mL with a correlation coefficient of 0.9928–0.9997. The limits of detection (LOD) for the six catechins were 4.62?μg/mL–11.63?μg/mL (S/N?=?3). The recoveries of the six catechins were 96.2%–108.4% with a relative standard deviation (RSD) between 0.78% and 4.51%. The method has been used for the determination of six catechins in tea samples with good results.     

亚微米C18键合硅胶固定相加压毛细管电色谱法同时拆分3种手性三唑类农药

采用改良Stöber法制备420 nm亚微米单分散二氧化硅微球,采用C18硅烷化修饰后装填成毛细管色谱柱。采用该色谱柱,在加压毛细管电色谱平台上成功地实现了3对手性三唑类农药烯效唑、烯唑醇和丙环唑的同时拆分和分离。考察了各因素对手性分离效果的影响,优化后的色谱条件为：流动相为乙腈-20 mmol/L磷酸盐缓冲液（pH=6.8）（45：55,v/v）,其中缓冲液中含20 mmol/L羟丙基-γ-环糊精（HP-γ-CD）;泵流速为0.04 mL/min;施加电压-9.4 kV;检测波长220 nm。在上述条件下,烯效唑、烯唑醇和丙环唑3种对映体同时得到拆分和分离,相邻两峰之间的分离度依次为4.20、12.9、4.41、4.09、1.70,分离时间仅为12 min,柱效最高达到310000 plates/m。该研究为手性三唑类农药的同时分离提供了新的分离分析思路。     

1 μm硅胶颗粒固定相的加压电色谱分离性能

制备了1 μm无孔硅胶颗粒。通过电动填充法得到总长度为45 cm(固定相填充长度为20 cm)、内径为100 μm的毛细管色谱柱。以乙腈-水体系作为流动相,详细考察了碱性化合物在该色谱柱上的加压电色谱(pCEC)分离性能,讨论了流动相比例、缓冲液浓度、pH值及操作电压等因素对分离的影响。实验结果表明,裸硅胶柱在乙腈-水体系分离碱性样品中表现出典型的反相色谱分离性能;缓冲液浓度的改变则对分离影响不大。当pH值改变时,碱性化合物的解离程度发生变化,它们与固定相之间的作用力发生变化,使得分离度发生相应的变化。分离柱效随施加电压的增加而增加,在1 kV电压下,裸硅胶柱对邻甲苯胺的柱效为35000理论塔板/m。