Photochemical properties of selected flavonol dyes: Effects on their separation using capillary electrophoresis

Flavonols are naturally occurring dyes that can be extracted from plants. Because of their antioxidant properties, they are thought to have health benefits. In this study, the photochemical degradation properties of selected flavonols were investigated. Dilute solutions of dyes were exposed to light from a broadband visible light source, and the rate of photodegradation was determined by measuring the decrease in fluorescence of the dyes with respect to time. At pH 9.24, the first-order rate constants for 10?µg?mL^?1 solutions of myricetin, quercetin, kaempferol, and morin were 0.468, 0.162, 0.108, and 0.126?s^?1, respectively. Interestingly, the stability of these historical dyes was also found to be greatly affected by pH. Awareness of the photochemical properties and stability of flavonol dyes is very important for capillary electrophoresis (CE) separations. Photodegradation of the flavonol dyes under the alkaline conditions (pH 9.2) used in CE can have a profound effect on the reproducibility of repeated separations. Even a modest decrease in pH (pH 8.5) greatly improved the stability of these dyes and enabled the successful separation of these flavonol dyes with minimal degradation over time.     

SPE及纳米金涂层毛细管电泳检测血浆中土霉素与多西环素

建立了混合型固相萃取及季铵化纤维素负载的纳米金涂层毛细管电泳法快速检测血浆中土霉素和多西环素的方法。采用季铵化纤维素负载的纳米金复合材料(QC-Au NPs)对毛细管内壁进行动态涂层,以抑制管壁对分析物的吸附,并对缓冲液p H值进行优化。结果表明,该涂层能改善峰形和分离度,提高分离效率,其中土霉素的柱效提高了17.9倍。在涂层毛细管中,土霉素和多西环素的吸附被抑制,并在4 min内出峰。在10~200μg/m L范围内,土霉素和多西环素的峰面积与浓度的线性关系良好,相关系数(r)分别为0.997 6和0.995 2。血浆中土霉素和多西环素的加标回收率为88%~107%,相对标准偏差(RSD)为1.4%~7.7%。该方法快速、简便,准确度和精密度高,适用于血浆中土霉素和多西环素的快速检测。     

Nonaqueous capillary electrophoresis of imatinib mesylate and related substances

In the present study, nonaqueous capillary electrophoretic separation of imatinib mesylate (IM) and related substances, N-(5-amino-2-methylphenyl)-4-(3-pyridyl)-2-pyrimidinamine (PYA), N-(4-methyl-3-(4-(pyridin-3-yl)pyrimidin-2-ylamino)phenyl)-4-((piperazin-1-yl)methyl) benzamide (NDI) and 4-chloromethyl-N-(4-methyl-3-((4-(pyridin-3-yl) pyrimidin-2-yl) amino) phenyl) benzamide (CPB) was developed. The influential factors affecting separation, including type and concentration of the electrolyte, applied voltage, and buffer modifier were investigated. Baseline separation of the studied analytes was obtained using a buffer of 50 mM Tris and 50 mM methanesulfonic acid in methanol at a apparent pH (pH*) of 1.65. To enhance the sensitivity, large-volume sample stacking was employed for online concentration. The strongest analytical signal with a suitable separation was achieved when the injection time was 100 s. The linearity ranges of PYA and NDI were 0.100-2.50 μg mL(-1) , and that of CPB was 0.125-2.50 μg mL(-1) , with good coefficients (r(2) > 0.9948). The relative standard deviations of intra- and interday were satisfactory. Under the optimized conditions, seven batches of the synthesized samples were analyzed and CPB was detected in two batches. Owing to its simplicity, effectiveness, and low price, the developed method is promising for quality control of IM.     

Enantioselective analysis of ofloxacin enantiomers by partial-filling capillary electrophoresis with bacteria as chiral selectors

The enantiomeric separation of ofloxacin enantiomers (OFLX) was achieved by using capillary electrophoresis partial-filled with Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) as chiral selectors. Experimental parameters, including the concentration of background electrolyte, applied voltage, length of the filled bacteria plug, and pH of the buffer, were intensively investigated. Baseline separation of OFLX could be achieved within 7 min by using E. coli and P. aeruginosa as chiral selectors under the following conditions: electrophoretic buffer composed of 10 mM phosphate buffer at pH 7.4, applied voltage at 15 kV, and the bacteria (6.0 × 10(8) cells/mL) were injected into the capillary by gravity with injection height of 17.5 cm for 180 s (E. coli), 300 s (P. aeruginosa), and 300 s (S. aureus), respectively. E. coli and P. aeruginosa had better chiral selectivity for OFLX than S. aureus, which was in good agreement with OFLX having better antimicrobial activity on Gram-negative rather than Gram-positive bacteria. A novel method was developed for the enantioselective separation of enantiomers using bacteria as chiral selectors, which provides a new approach for antimicrobials enantioselective analysis, chiral pharmacodynamics, and chiral pharmacokinetics studies.     

Determination of thiols by capillary micellar electrokinetic chromatography with laser induced fluorescence detection using 1,3,5,7‐tetramethyl‐8‐phenyl‐(4‐iodoacetamido) difluoroboradiaza‐s‐indacene as labeling reagent

A sensitive and effective micellar electrokinetic capillary chromatography with laser‐induced fluorescence detection approach was described for the determination of low molecular‐mass thiols using 1,3,5,7‐tetramethyl‐8‐phenyl‐(4‐iodoacetamido) difluoroboradiaza‐s‐indacene as the labeling reagent. After precolumn derivatization, baseline separation of six thiol compounds including cysteine, glutathione, N‐acetylcysteine, homocysteine, 6‐mercaptopurine, and penicillamine were achieved within 18 min. The optimal running buffer was composed of mixtures involving 25 mM sodium dodecyl sulfate, 25% (v/v) acetonitrile and 15 mM sodium phosphate buffer, pH 7.5. The detection limits (S/N = 3) were found as low as 40 pM under argon ion laser‐induced fluorescence detector (λ_ex/λ_em = 488/520 nm), which were much better than the reported approaches. The accuracy and specificity of this assay for real samples were assured by a standard addition method. The proposed method has been applied to the analysis of thiols both in human plasma and plum flower samples with recoveries of 92.0–109.4%.     

Simultaneous analysis of Cu and Pb as ABEDTA complexes in Rhizoma coptidis by capillary electrophoresis coupled with solid phase extraction

A novel capillary electrophoresis method for simultaneous determination of Cu and Pb has been developed in this paper.Cu（Ⅱ） and Pb（Ⅱ） ions were reacted with ABEDTA to form complex to achieve an ideal sensitivity of heavy metal complexes.The digestion solution of Rhizoma coptidis drug sample was purified by neutral Al₂O₃ column chromatography and the chromatographic behavior of metal-L complexes was investigated.The calibration curve was linear in the range of 5-60μg/mL for Cu²⁺ and 5-25μg/mL for Pb²⁺ with the correlation coefficients 0.9970 and 0.9972 for each（n = 5）.The average recoveries were 86.2%for Pb and 90.1%for Cu,while the relative standard deviations were 5.1%and 3.6%respectively.The method was successfully applied to determine Cu and Pb in R.coptidis drug samples.     

毛细管电泳/发光二极管诱导荧光法测定麻黄中麻黄碱与伪麻黄碱含量

基于麻黄碱及伪麻黄碱衍生物的光谱及化学性质,设计并构建了毛细管电泳/发光二极管诱导荧光检测系统.对关键光学元件进行组合选择,以蓝光发光二极管为光源,BP 470和BP 530分别为光源滤光片和荧光滤光片,光电倍增管检测信号,并对电泳分离系统的缓冲溶液、分离电压等参数进行优化;以FITC为衍生试剂,10 mmol/L Na2B4O7+ 16 mmol/L SDS为缓冲溶液,12 kV电压下可实现麻黄中麻黄碱和伪麻黄碱的基线分离.在0.25～10 mg/L范围内,麻黄碱和伪麻黄碱标准溶液的质量浓度与荧光响应的峰高之间呈较好的线性关系,相关系数(r)均大于0.99,其检出限分别为0.38 μg/L和0.29 μg/L,峰高的日内重复性(RSD)分别为2.0％和2.2％,日间重复性(RSD)分别为5.4％和5.1％.将该方法用于中药麻黄中麻黄碱和伪麻黄碱的测定,加标回收率分别为94％和107％.     

非水毛细管电泳法分离3种单磷酸腺苷及其应用研究

采用非水毛细管电泳方法对2’-AMP、3’-AMP和5’-AMP 3种单磷酸腺苷进行分离研究,考察了电泳溶液pH*值、非水介质、缓冲溶液对分离的影响。以含50%乙腈的Tris-H3BO3体系为缓冲溶液,在pH*10.0、压差进样(50 mbar,5 s)、柱温25℃、25 kV恒压下进行分离,在波长260 nm处负极检测,各组分可达到基线分离。在质量浓度为1～100 mg/L范围内,3种单磷酸腺苷的线性关系良好,平均回收率为88%～106%,RSD小于4%。该方法应用于核苷样品的测定,结果满意。     

毛细管区带电泳法分析不同来源血竭中龙血素A和龙血素B

在系统优化了电解质溶液的pH、组成、浓度及仪器条件的基础上,建立了一种测定不同来源血竭中龙血素A和龙血素B的毛细管区带电泳(CZE)方法。采用20 kV的分离电压,25 ℃的毛细管柱温,211 nm的检测波长以及5 s的压力(3447 Pa)进样时间,在20 mmol/L的Na2B4O7缓冲溶液(用NaOH调节pH到9.98,含有10%(v/v,下同)乙腈、5.0%乙二醇和1.0%正丁醇)中,龙血素A和龙血素B在15 min内得到了有效分离与检测。方法的线性范围对于龙血素A和龙血素B分别为1.0～100.0 mg/L和0.5～100.0 mg/L。将该方法用于天然血竭及人工诱导血竭中龙血素A和龙血素B的测定,相对标准偏差在0.6%～3.8%之间,加标回收率在95.1%～105.8%之间。方法具有简单、快速、重现性较好和准确度较高的优点,可以用于血竭样品中龙血素A和龙血素B的测定。     

毛细管区带电泳法测定冬虫夏草及鹿茸制品中核苷和碱基成分

应用毛细管区带电泳法测定分别以冬虫夏草菌丝体粉和鹿茸血为主要原料制品中的多种核苷和碱基成分。对实验条件进行了优化,结果表明,以20mmol/L硼砂-15mmol/Lβ-环糊精为缓冲溶液(pH=9.4),分离电压22kV,检测波长254nm,电动进样为10kV、5s时,在10min内同时分离测定了虫草素、腺嘌呤、鸟嘌呤、尿嘧啶、腺苷、次黄嘌呤、尿苷、鸟苷和肌苷。各组分在0.2～200μg/mL范围内呈线性关系,检出限的范围是0.07～1.67μg/mL。5个批次的冬虫夏草菌丝粉保健品中腺嘌呤、尿嘧啶、腺苷、鸟苷、尿苷5组分的定量结果分别在0.15～0.19mg/g、0.72～0.92mg/g、1.44～1.59mg/g、1.51～2.32mg/g和1.77～2.56mg/g范围内,加标回收率的范围是82.83%～109.21%;2个批次的鹿茸血保健品中次黄嘌呤、尿苷的定量结果在36.55～49.97μg/mL和86.08～108.97μg/mL范围内,加标回收率的范围分别是89.68%～96.79%和99.05%～102.81%。