迁移时间归一化法改善毛细管电泳表征中药大黄的重现性

探讨了迁移时间归一化法改善中药毛细管电泳分析迁移时间重现性的原理,并将其应用于实际样品的分析。迁移时间归一化法认为,在相同的操作电压、缓冲液组成和温度条件下,多次电泳实验中迁移时间产生差别的主要原因是多次电泳实验中电渗流产生了差异。迁移时间归一化法就是通过选择电泳谱图中的一个或两个峰作为标记峰,将各次电泳实验的迁移时间都归一到第一次电泳实验中的迁移时间。比较多次电泳实验中迁移时间(t)的相对标准偏差(RSD)、经单峰归一化处理的迁移时间(t′)的RSD、经双峰归一化处理的迁移时间(t″)的RSD、迁移时间比(t/tistd,istd代表所选择的标记物)的RSD,发现RSD(t″)相似文献   

毛细管电泳指纹图谱应用于叶下珠药材中黄酮的检测

建立了叶下珠药材中黄酮的毛细管电泳指纹图谱。以硼砂和十二烷基磺酸钠(pH9.0)为背景电解质溶液,运行电压15kV,紫外检测波长245nm,流体静压力进样15s(高度12cm),对不同产地叶下珠药材进样检测。按电泳峰共有率fi≥70%为依据,确定10个不同产地叶下珠药材中黄酮的毛细管电泳指纹峰为8个,各产地叶下珠的毛细管电泳指纹图谱与标准毛细管电泳指纹图谱的相似度较好。在制备供试液后不同时间进样测定,各指纹峰的相对迁移时间的相对标准偏差小于5%,相对峰面积的相对标准偏差在3.0%～7.8%之间,结果表明样品在48h内稳定。     

毛细管电泳法快速检测消毒剂中的醋酸氯己定

建立了消毒剂中活性成分醋酸氯己定(又名:醋酸洗必泰)的毛细管电泳快速检测法。采用15 mmol/L磷酸盐-乙腈( 体积比为60∶40)缓冲体系,将醋酸氯己定在50 cm×75 μm i.d.的石英毛细管柱中进行电泳分离,电泳电压为15 kV,检 测波长为254 nm。同时,对毛细管电泳分析醋酸氯己定的条件(如缓冲液的种类、pH值、浓度及电泳电压等)进行了优化 。用该方法对消毒剂样品进行测定,在4 min内可完成分析。醋酸氯己定在质量浓度为0.01～0.10 g/L时线性良好,检测 限为0.004 mg/L,吸光度值的相对标准偏差为3.97%,迁移时间的相对标准偏差为2.99%,样品加标回收率为91.4%～116.6%。将该方法 与高效液相色谱法进行比较,两种方法测定结果的相对误差≤4%。所建立的检测醋酸氯己定含量的毛细管区带电泳法简单 、快速,适用于消毒剂样品的测定。     

高效毛细管电泳 间接紫外吸收检测法测定食品中的氨基酸

研究了鸟氨酸、脯氨酸和谷氨酰胺的高效毛细管电泳 间接紫外吸收检测的特征。以5　mmol/L 对氨基苯磺酸钠 10 mmol/L KH2PO4(pH 11.5)为运行缓冲液,在分离电压12 kV下,于11 min实现了上述3种氨基酸的基线分离,迁移时间和峰高的相对标准偏差分别小于0.72%和2.0%,检测限分别为6.78,8.71,7.86 mg/L。应用该法测定食品中的氨基酸及各氨基酸在样品中的加标回收率,3种氨基酸的加标回收率为96.8%~104%。     

阴离子选择性耗尽进样-胶束扫集毛细管电泳法对痕量醋酸氢化可的松的测定

联用阴离子选择性耗尽进样和胶束扫集两种在线富集技术,建立了胶束毛细管电泳方法测定化妆品中醋酸氢化可的松的方法。讨论了SDS浓度、样品基体、进样电压、进水时间和进样时间对富集和分离的影响。优化的实验条件:以120 mmol/L SDS-20 mmol/L NaH2PO4(pH2.2)-10%(体积分数)甲醇为缓冲体系,分离电压-20 kV,进样电压-20 kV,进样时间80 s,进水时间200 s,测量波长250 nm。在该实验条件下,醋酸氢化可的松的富集倍数比普通毛细管电泳法提高了约173倍。方法的线性范围为0.05~5.0 mg/L,检出限为12.6μg/L。该方法用于化妆品中醋酸氢化可的松含量的测定,回收率为98%~105%,相对标准偏差均小于4.0%(n=4)。     

在线富集-毛细管区带电泳法测定牛奶中三聚氰胺

提出了在线富集毛细管区带电泳法测定牛奶中三聚氰胺的含量。系统地考察了毛细管区带电泳工作条件,选定的试验条件为:①磷酸盐缓冲溶液浓度为20 mmol.L-1;②pH值为3.0;③运行电压为30 kV;④检测波长为208 nm。在优化的试验条件下,三聚氰胺在8 min内达到基线分离,其线性范围为0.83～106.70 mg.L-1,检出限(3S/N)为0.2 mg.L-1。在制备供试液后不同时间进样测定,三聚氰胺迁移时间的相对标准偏差为0.72%,峰面积的相对标准偏差为1.02%,结果表明样品在8 h内稳定。     

连翘的毛细管电泳指纹图谱研究

采用毛细管区带电泳法,以75 mmol/L硼砂溶液(用0.1 mmol/L氢氧化钠溶液调pH 9.7)为背景电解质,运行电压14 kV,检测波长228 nm,重力进样15 s(高度9 cm),建立了连翘药材的毛细管电泳指纹图谱(CEFP)。将10个不同产地的连翘药材进行比较,按各电泳峰共有率fi≥70%作为选择电泳指纹峰的依据,确定连翘的毛细管电泳指纹峰为29个。在方法的精密度和重复性试验中,各指纹峰的相对迁移时间的相对标准偏差(RSD)不大于5%,相对峰面积的RSD约为2%~15%。10个产地的连翘药材的CEFP与其对照CEFP的相似度均不低于0.94。同时,采用指纹图谱信息量指数I和相对信息量指数Ir评价了10个产地连翘药材的质量差异。     

功能食品与饮品中牛磺酸的柱前衍生-高效毛细管电泳法快速测定

建立了功能食品和饮品中牛磺酸的高效毛细管电泳快速分析方法。以邻苯二甲醛(OPA)为衍生剂进行柱前衍生,采用45 mmol/L(pH9.5)的硼砂缓冲溶液为运行缓冲溶液,熔融石英毛细管(50 cm×50μm,有效长度41 cm,未涂层)为分离柱;柱上紫外检测波长:335 nm,分离电压19 kV,电泳温度20℃,重力进样,进样时间10 s。牛磺酸的质量浓度在5.0~100.0 mg/L范围内呈良好线性关系(r0.999),检出限(S/N=3)为1.6 mg/L,迁移时间和峰面积的相对标准偏差(n=7)分别为2.4%和3.8%。用该法测定了功能食品、乳制饮品和饮料等样品中的牛磺酸,相对标准偏差为0.7%~3.7%,加标回收率为93%~111%。     

高效毛细管电泳在兴奋剂检测中的应用进展

对高效毛细管电泳(HPCE)在兴奋剂检测方面的工作进行了评述,讨论了高效毛细管电泳不同分离模式在兴奋剂检测中的应用,并对这一领域的发展趋势进行了展望。     

人血胃泌素的毛细管电泳定量测定

用自制涂渍毛细管柱在HPE-100毛细管电泳仪(Bio-Rad USA)上以区带电泳模式对胃泌素作定量测定。苯甲酸被用作内标。用胃泌素和苯甲酸的峰高比对胃泌素浓度作图,在1～8 mg/L内测得其浓度标准曲线,相关系数达0.9994,截距接近于0,结果优于用峰面积得到的数值。在同种浓度下,5次测量迁移时间的相对标准偏差(RSD)小于0.7%,不同浓度下的24次平行操作的相应值在0.9%～1.1%之间。胃泌素测定的绝对量为0.38pg,即3.6×10~(-15)mol。     

Selectivity of two types of sulfadimidine-imprinted monolithic polymer-based fibers

Molecularly imprinted polymeric monolithic fiber is a new technique of solid-phase microextraction that focuses on selectivity. However, the inner mechanism of increasing the selectivity is not well understood. Here, a new approach to improve the selectivity is shown through controlling the surface of a molecular imprinted polymeric monolithic fiber. Sulfadimidine-imprinted polymeric monolithic fibers were fabricated using two kinds of molds, the polytetrafluoroethylene capillary and the silica capillary. A mixture of sulfadimidine, sulfamerazine, sulfadiazine, and sulfametoxypirydazine was used to test the selectivity of the fibers to sulfadimidine. This paper demonstrates that the extraction ratio for sulfadimidine in mixture is increased to more than 150% in sulfadimidine-imprinted polymeric monolithic fiber compared to nonimprinted polymeric monolithic fiber. The extraction ratio is increased to about 30% in sulfadimidine-imprinted polymeric monolithic fiber fabricated from silica capillary than in the counterpart from nonimprinted polymeric monolithic fiber. The sulfadimidine-imprinted polymeric monolithic fibers were also applied to extract standard mixtures spiked into Pearl River water and milk. The results indicated that polytetrafluoroethylene-sulfadimidine imprinted polymeric monolithic fiber showed highest selectivity to sulfadimidine in complex samples.     

Reproducibility of sample separation using liquid or forced air convection thermostatted high performance capillary electrophoresis systems

Run-to-run sample separation reproducibility has been compared on two commercial high performance capillary electrophoresis units which differ in the mode by which the capillary temperature is thermostatted. Three standard analytes, differing dramatically in molecular character and size, were used for the analysis: benzoic acid, a 14 amino acid peptide from human chorionic gonadotropin, and ribonuclease A represent, respectively, small stable organic molecules, small peptides with little or no secondary structure, and proteins with secondary structure. These standards were evaluated with regard to reproducibility of migration time, peak area, and peak height. The analyses, performed in buffers of optimum pH for the separations, demonstrated that the liquid and forced air convection thermostatted systems both performed extremely well. The reproducibility, as judged by the percent coefficient of variance (% CV) of replicate analyses, was generally found to be less than 1 % (migration time); the reproducibility decreased in the order migration time > peak height > peak area. Whereas the absolute % CV values for MT_rel (migration relative to a standard) observed with the liquid thermostatted system were 2- to 4-fold lower than those observed with the forced air convection thermostatted system, there was little statistically significant difference between the two. As expected, the data indicated a reduction in reproducibility as the complexity of the analyte increased, perhaps as the result of an increased potential for wall interactions. Comparing separations in which low (≈?1 watt/meter [W/m] of capillary) and high (>5 W/m) Joule heat was generated by altering the sodium chloride content of the buffer revealed few statistically significant differences in the reproducibility obtained from the two systems. With these particular standard analytes and their respective buffer systems, there appears to be little difference between forced air convection and liquid thermostatting of the capillary.     

Determination of berberine in Rhizoma coptidis and its preparations by non-aqueous capillary electrophoresis

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.     

Determination of individual microsphere properties by capillary electrophoresis with laser-induced fluorescence detection

Capillary electrophoresis with postcolumn laser-induced fluorescence detection was used to individually detect 6.0, 1.0, 0.5, and 0.2 num diameter polystyrene microspheres and individually measure their electrophoretic mobility. The analysis of a nanoliter-size volume from a microsphere suspension results in an electropherogram characterized by several narrow spikes in a well-defined migration time window. Each spike is associated with one microsphere because, when one single microsphere is introduced into the capillary by micromanipulation, the electropherogram has only one spike in the same migration time window. The distributions of individual measurements resulting from an electropherogram were used to evaluate the reproducibility from run to run, observe the effect of sodium dodecyl sulfate (SDS) added to the running buffer, and to investigate the origin of electrophoretic dispersion. As expected from the interactions between microspheres and SDS, the addition of this surfactant to the running buffer narrowed the range and shifted the average electrophoretic mobility to more negative values. After evaluating common sources of broadening in capillary electrophoresis, electrophoretic dispersion was attributed to microsphere heterogeneity. Unlike electropherograms displaying Gaussian-like profiles, the two-dimensional representations of the individual measurements provide a new alternative to evaluate and study electrophoretic-related properties of microspheres.     

Determination of baicalein, baicalin and quercetin in Scutellariae Radix and its preparations by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection (CE-ED) was developed for the determination of baicalein, baicalin and quercetin in Scutellariae Radix and its pharmaceutical preparations. The effects of some important factors such as the acidity and concentration of running buffer, separation voltage, injection time, and the potential of working electrode were investigated to acquire the optimum condition. The working electrode was a 300-mum diameter carbon disc electrode positioned opposite the outlet of capillary. The three analytes could be well separated within 12 min in a 40 cm length capillary at the separation voltage of 12 kV in a 100 mmol l(-1) borate buffer (pH 9.0). The response was linear over three orders of magnitude with detection limits (S/N=3) ranged from 0.224 to 0.548 mumol l(-1) for all three analytes. This proposed method demonstrated good long-term stability and reproducibility with R.S.D. of less than 5% for both migration time and peak current (n=7). It has been successfully applied to analyze the actual samples with satisfactory assay results.     

基于场放大进样和石墨烯量子点双重富集毛细管电泳分离检测三聚氰胺和双氰胺

通过热解法制备了硫掺杂的石墨烯量子点(S-GQDs),同石墨烯量子点(GQDs)相比,S原子的引入有效改善了GQDs的表面状态和化学特性、增强其对正电荷的捕获能力,使其更易与阳离子相互作用.以S-GQDs为载体,结合电堆积富集技术,发展了一种基于场放大进样(FASI)和S-GQDs放大的双重富集毛细管电泳(CE)分离检...     

Electropherograms in capillary zone electrophoresis plotted as a function of the quantity of electric charge

We have plotted electropherograms in capillary zone electrophoresis (CZE) as a function of the quantity of electric charge (Q) in order to eliminate the dependency of the analyte peak areas, as well as that of the migration times, upon both the capillary temperature and the applied voltage. The procedure is based on an idea of a migration index (MI) and an adjusted migration index (AMI) which were originally proposed by Lee and Yeung. The value of Q is measured accurately and calculated easily because it is given by a product of the electrophoretic current and the migration times, where the index MI is derived by dividing the value of Q by the effective volume of the capillary. By calculating the CZE peak area from the newly plotted electropherogram, improvement in precision in quantitative analysis is expected. Concerning AMI, careful treatment is required in its application to analyte peaks whose migration time is close to that of the neutral marker. Experimental data and discussions concerning the migration indices are presented.     

Capillary-electrochromatographic separations with copolymeric reversed-stationary phase and ion-exchanger-packed columns

A macroporous, spherical, 7 μm, polystyrene–divinylbenzene (PS–DVB), reversed-phase adsorbent (PRP-1) was evaluated as a stationary phase for the capillary electrochromatographic (CEC) separation of neutral, acidic, and basic analytes of pharmaceutical interest. Electroosmotic flow (EOF) for a PRP-1 packed capillary is nearly constant over the pH 2 to 10 range and is higher than for a silica-based C₁₈ packed capillary on the acidic side. EOF increases with an increase in buffer acetonitrile concentration or as applied potential increases. As analyte hydrophobicity increases, analyte retention and migration time increases. Increasing buffer acetonitrile concentration reduces analyte partitioning with the PS–DVB stationary phase and analyte retention and migration time decreases. When exchange sites are present on the PS–DVB copolymer, EOF (EOF is reversed for the anion-exchanger) increases as the exchange capacity increases. An increased exchange capacity also reduces partitioning of the analyte with the PS–DVB matrix and analyte retention and migration time decrease. Because of excellent stability in an acid environment, the PRP-1 packed capillary can be used in strong acid buffer solution and weak acid and base analytes depending on pK_a values can be separated as neutral species and cations, respectively. CEC separations on a PRP-1 capillary of neutral steroids, weak base pharmaceuticals (separation as cations), purines and pyrimidines (as cations), fatty acids (as undissociated species), and sulfa derivatives (as cations) are described. Efficiency for the PRP-1 packed capillary for acetone or thiourea as the analyte is about 6·10⁴ plates m⁻¹.     

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。     

Determination of purine and pyrimidine bases in DNA by micellar electrokinetic capillary chromatography with electrochemical detection

A method based on micellar electrokinetic capillary chromatography with electrochemical detection was developed for the determination of cytosine, 5-methylcytosine (5-MC), thymine, adenine, and guanine in the hydrolysates of DNA. The working electrode was fabricated in a novel self-positioning carbon disc electrode system that can align the capillary outlet with the working electrode without a three-dimensional micromanipulator. The five analytes could be well separated within 10 min in a 40 cm length capillary at a separation voltage of 9 kV in a 40 mmol/l borate buffer (pH 10.0) containing 100 mmol/l sodium dodecyl sulfate. Good linearity was observed between peak current and concentration of bases over three orders of magnitude with the detection limits (SIN=3) ranging from 1.28 x 10(-6) to 5.02 x 10(-6) mol/l. This proposed method demonstrated long-term stability and reproducibility with relative standard deviations of less than 5% for both migration time and peak current (n=7). It has been successfully applied to determine bases including 5-MC in the hydrolysates of fish sperm DNA, calf thymus DNA, and DNA isolated from spleen cells of female mice.