非水毛细管电泳应用新进展

非水毛细管电泳(NACE)已经被广泛用于药物、环境和生物等领域。由于有机溶剂种类繁多,它们的物理和化学性质各不相同,因此可以针对被分析物的性质及检测方法的不同,选择不同的有机溶剂用于NACE分离,从而拓宽了毛细管区带电泳(CZE)的应用范围。本综述根据近年来NACE在分析领域的应用,对NACE的优势、检测方法、富集方式以及在实际样品中的应用等方面进行了总结,并对其今后的发展进行了展望。     

非水毛细管电泳进展

 毛细管电泳通常是在以水为溶剂的缓冲溶液中进行的,事实上以纯有机溶剂替代水介质同样可以完成特殊样品的电泳分离,且存在诸多优点。以所建立的非水毛细管电泳方法为核心,总结了该方法中有机溶剂、电解质的选择原则及溶质-添加剂相互作用模式,并综述了它在无机离子、中性物质、有机酸等化合物分离分析中的应用。71篇。     

电堆集富集非水毛细管电泳同时测定水杨酸、肉桂酸、阿魏酸和香草酸

建立了同时分离测定水杨酸、肉桂酸、阿魏酸和香草酸的电堆集富集-非水毛细管电泳(NACE)的新方法。运行缓冲溶液为40mmol/L乙酸钠-2.5mmol/L氢氧化钠甲醇溶液,电压-25kV,在225nm波长下紫外检测。对电压、乙酸钠浓度、氢氧化钠浓度、进样时间、样品溶液等因素对电堆集及分离的影响做了系统的研究。水杨酸、肉桂酸、阿魏酸和香草酸分别在1.4~28mg/L、0.40~8.0mg/L、0.7~18mg/L和0.7~30mg/L范围内线性关系良好(r=0.9999、r=0.9997、r=0.9994、r=0.9997);回收率分别为95.8~99.6%、96.2~98·2%、95.7~105%和98.9~103%,基于3倍信噪比(S/N=3),4种有机酸的检出限分别为0.069、0.051、0.107和0.089mg/L。     

非水介质毛细管电泳

评述了与水相体系相比,非水体系电泳分离体系对分析对象的扩展、分离度和分离效率的改善、选择性的提高以及质谱检测联用技术等各方面带来的好处,同时还总结了非水介质各种参数对毛细管壁双层ζ电位、电渗流以及分离效率、分离度的影响。     

毛细管电泳样品电堆积富集过程的数值研究

毛细管电泳样品电堆积富集过程可以浓缩样品组分,从而提高检测灵敏度,是一种有效的样品富集技术。本文通过合理的简化和假设,把毛细管中电堆积富集过程中所涉及的主要变量根据电势分布方程、缓冲溶液的浓度方程和样品粒子的质量传输方程进行耦合求解,建立了一个一维的数学模型,并应用有限元的方法对该模型进行了求解。计算结果给出了毛细管中缓冲溶液浓度及电场强度的分布随时间变化的过程,以及富集过程中毛细管中的电势分布曲线;得到了样品粒子浓度在电堆积富集过程和富集之后的再次扩散过程中的分布曲线以及正、负样品粒子的分离过程;最后分析了不同缓冲溶液浓度比对样品富集效果的影响。该研究为样品电堆积富集技术的进一步完善提供了一种简单可行的理论研究方法。     

电堆集-场放大进样非水毛细管电泳法测定苦参中的三种生物碱

建立了电堆集-场放大进样非水毛细管电泳法分离测定苦参中的槐定碱、苦参碱和氧化苦参碱。采用未涂层熔融石英毛细管(50cm×50μm i.d.,有效柱长36cm),紫外检测波长为209nm,运行缓冲溶液为50mmol/L乙酸铵-20%乙腈-0.75%乙酸-55%甲醇,分离电压20kV,电动进样20kV、15s,重力进水柱时间20s时达到最佳的分离效果。在优化条件下,上述三种生物碱均在15min内出峰,峰面积的相对标准偏差(RSD)均小于5%。检出限分别达到2.02μg/L、1.32μg/L和1.01μg/L。     

毛细管电泳中样品的在线富集

由于毛细管进样体积小以及在柱检测光程短,极大地限制了毛细管电泳检测灵敏度的提高.为了提高毛细管电泳的检测灵敏度,多种样品富集的方法得以发展.本文对近年来毛细管电泳的样品预富集方法与应用作一简明的综述。     

非水毛细管电泳法测定藤黄中藤黄酸的含量

藤黄酸(gambogic acid, GA)等环氧杂蒽酮类化合物的水溶性差,可通过非水毛细管电泳(non-aqueous capillary electrophoresis, NACE)分析。本文系统地考察了添加20%~60%(v/v)的甲醇或乙腈的运行电解质溶液对藤黄提取液中藤黄酸分离的影响。比较了不同的运行电解质溶液、运行电解质溶液浓度、pH、添加剂 β-环糊精的浓度、分离温度及分离电压的影响,建立了测定藤黄药材中藤黄酸含量的非水毛细管电泳方法。在40%乙腈、10 mmol/L β-环糊精、20 mmol/L四硼酸钠(pH 9.86)为运行电解质溶液、分离电压为10 kV、分离温度为30 ℃、检测波长为280 nm的条件下进行测定。结果表明,藤黄酸在2~2000 mg/L范围内线性关系良好,相关系数为0.9996,检出限(S/N=3)为2 mg/L。将本方法应用于越南、泰国、缅甸、印度4个产地的藤黄药材中藤黄酸的含量测定,测得含量为1.67~472.40 mg/g(相对标准偏差(RSD)为1.12%~2.60%),其中越南产藤黄中藤黄酸含量低,其他产地藤黄中藤黄酸的含量高。实际藤黄样品中藤黄酸的加标回收率为95.2%~105.6%。非水毛细管电泳方法简单、快速、重现性好,可用于藤黄药材中藤黄酸的含量测定。     

非水毛细管电泳法测定芬布芬含量的研究

本文建立了非水体系高效毛细管电泳法测定芬布芬的新方法。考察了运行电压、非水介质和电解质等因素的影响。选择15 mmol/LNaAc-25 mmol/L十六烷基三甲基溴化铵(CTAB)为电泳介质,甲醇为溶剂,紫外检测波长281 nm,分离电压-25 kV,13 min内可以实现芬布芬的分离检测。在优化条件下,药物中辅料不干扰芬布芬的测定,加标回收率为98.2%~103.1%。方法简便、快速,可用于芬布芬片中芬布芬含量的测定。     

非水介质毛细管电泳高频电导法测定姜黄中姜黄素

建立了药材姜黄中姜黄素含量的非水介质毛细管电泳高频电导测定方法.对非水介质体系和支持电解质的种类,浓度以及操作电压和进样时间等影响因素进行了优化.以无水甲醇作为分离介质,NH4OAc-HOAc为电解质,25.0 kV为分离电压,可在12 min内实现对姜黄素的分离检测.在最佳试验条件下,姜黄素的线性范围为3.0～140.0 mg·L-1,检出限为0.5 mg·L-1,回收率为95.3%～100.9%.     

Determination of ephedrine alkaloid stereoisomers in dietary supplements by capillary electrophoresis

Three complementary capillary electrophoresis (CE) methods were developed for the separation and quantification of ephedrine and pseudoephedrine stereoisomers. Either single or dual cyclodextrin-based chiral selector systems provided enantioselective separation of the compounds of interest. The three methods were applied to the analysis of a suite of five standard reference materials (SRMs) containing ephedra. Use of a high-sensitivity UV detection cell enhanced quantification of the analytes of interest over the wide range of concentrations encountered in the SRMs. Results for (-)-ephedrine ranged from 0.31 to 76.43 mg/g, and for (+)-pseudoephedrine ranged from 0.049 to 9.23 mg/g in the materials studied. Results from the three methods agreed well with each other and with the results from other methods of analysis. The addition of known amounts of specific enantiomers was used to confirm the enantiomeric identity of the analytes. The results obtained by the three CE methods were utilized for value assignment of the ephedrine alkaloid content of these five SRMs.     

非水介质毛细管电泳电导检测罗红霉素及其制剂

采用甲醇为分离介质，三(羟甲基)氨基甲烷-硼酸(Tris—H3BO3)为支持电解质，采用负高压，使用电导检测，对罗红霉素及其制剂进行了毛细管电泳分离检测，对电泳介质的种类、浓度、表观pH、以及操作电压和进样时问对分离的影响进行了研讨，在选定的条件下，罗红霉素的线性范围为19．0—142．0mg/L，检出限为0．8mg/L(S／N≥3)，峰面积的相对标准偏差RSD(n=6)为4．3％。3种供试品中罗红霉素的平均加标回收率分别为97．7％、94．8％、93．6％。     

Solvent-bar microextraction of herbicides combined with non-aqueous field-amplified sample injection capillary electrophoresis

Solvent-bar microextraction (SBME) based on two-phase (water-to-organic) extraction was for the first time used as the sample pretreatment method for the non-aqueous capillary electrophoresis (NACE) of herbicides of environmental concern. Due to the compatibility of the extractant organic solvent and the NACE separation system, the extract could be introduced directly to the CE system after SBME. Through investigations of the effect of sample pH, extraction time, agitation speed and salt addition on extraction efficiency, the most suitable extraction conditions were determined: sample solution at a pH of 1, without added salt, and stirring at 700 revolutions per minute for 30 min. SBME as applied here was also compared with single-drop microextraction and hollow fiber-protected liquid-phase microextraction. SBME showed the highest extraction efficiency. In addition, field-amplified sample injection with pre-introduced organic solvent plug removal using the electroosmotic flow as a pump (FAEP) was used to enhance the sensitivity further in NACE. Based on studies of the effect of different organic solvents, different lengths of the organic plugs and different volumes of sample injection on stacking efficiency under the most suitable separation conditions, methanol was found to be the most efficient solvent for on-line preconcentration. Combined with SBME, FAEP-NACE achieved limits of detection of between 0.08 ng/mL and 0.14 ng/mL for the studied analytes. This preconcentration approach for NACE was demonstrated to be amenable to aqueous environmental samples by applying it to spiked river water.     

Determination of glutathione in blood via capillary electrophoresis with pH-mediated stacking

A new approach has been developed for the direct determination of reduced (glutathione [GSH]) and oxidized (glutathione disulfide [GSSG]) GSH in whole blood by means of capillary electrophoresis. Its features include GSH-stabilizing sample preparation, the use of an internal standard, and pH-mediated stacking. Blood stabilized with acid citrate and K₃EDTA was treated with acetonitrile with N-ethylmaleimide, and then the analytes were extracted with diethyl ether. The total analysis time was 8 min using a 50-µm (i.d.) by 32.5-cm (eff. length) silica capillary. The background electrolyte was 0.075-M citrate Na pH 5.8 with 200-µM cetyltrimethylammonium bromide and 5-µM sodium dodecyl sulfate, and the separation voltage was −14 kV. The quantification limit (S/N = 15) of the method was 1.5 µM for GSSG. The accuracy levels of GSH and GSSG analysis were 104% and 103%, respectively, and between-run precision levels were 2.6% and 3.2%, respectively. Analysis of blood samples from healthy volunteers (N = 24) showed that the levels of GSH and GSSG and the GSH/GSSG ratio in the whole blood were 1.05 ± 0.14 mM, 3.9 ± 1.25 µM, and 256 ± 94, respectively. Thus, the presented approach can be used in clinical and laboratory practice.     

毛细管电泳-场强放大样品堆积法检测染发剂中的7种苯胺类物质

建立了毛细管电泳-场强放大样品堆积测定染发剂中4,4′-二氨基二苯甲烷、苯胺、邻甲氧基苯胺、对氨基苯甲醚、3,4-二甲基苯胺、间氨基苯酚、1-萘胺7种苯胺类物质的分析方法。在优化的缓冲溶液体系(0.15 mol/L NaH2PO4,0.015 mol/L 三乙醇胺, pH 2.3)下7种分析物在6.5 min内实现基线分离。考察了样品中添加的磷酸浓度和乙腈浓度、水柱长度、电动进样时间与电压对场强放大富集效率及重现性的影响。最佳的富集条件为: 水柱注入3.45 kPa(0.5 psi)×6 s,样品中添加40%(v/v)乙腈和0.6×10~3mol/L磷酸,进样电压与进样时间为10 kV×10 s。线性范围为3～1000 μg/L(R2＞0.996),检出限为0.26～2.75 μg/L,将已有方法的检测灵敏度提高了1～3个数量级。在2种市售黑色染发剂中均检测到间氨基苯酚,含量分别为7.32 mg/g和1.34 mg/g。平均加标回收率为74%～108%。该方法灵敏度高、快速、重现性好、成本低,可供多种样品基质中痕量苯胺类污染物及其他阳离子物质的测定借鉴使用。     

Capillary electrophoresis of methylmercury with injection by sample stacking

A procedure for separation and quantitation of methylmercury by capillary electrophoresis using sample stacking as the injection technique is presented. The CE conditions have been optimized in order to separate the methylmercury from the excess cysteine peak and to concentrate large volumes of sample obtaining a low detection limit. Under the proposed operational conditions, the detection limit (S/N = 3) was 12 ng g⁻ and the limit of quantitation (S/N = 10) was 20 ng g⁻¹ with a linear range of 20–100 ng g⁻¹ (as methylmercury in samples). The method was tested using different reference materials with a certified methylmercury content.     

Separation of alkylbenzyl quaternary ammonium compounds by capillary zone electrophoresis with sample stacking injection

Summary A systematic investigation of operational buffer systems, sample preparation and instrument parameters for achieving the best possible performance for determinating an homologous series of N-benzyl-N-alkyl-N,N-dimethylammonium chloride compounds by capillary zone electrophoresis with direct UV detection. The most effective separation was achieved within 3.5 min with the addition of acetonitrile (40%) in a phosphate buffer (20 mM pH 5.2) using a 40 cm fused-silica capillary operating at 25 KV and 20°C. Degassing of all electrolyte solutions and samples was very important. The linearity and repeatability for each compounds were satisfactory. To improve detection limits, on-column sample preconcentration, sample stacking, was investigated achieving a tenfold enrichment factor and quantitation limits about 10⁻⁷M.     

胶束扫集毛细管电泳快速测定止咳露中的麻黄碱和可待因

采用胶束扫集毛细管电泳, 建立了快速测定止咳露中麻黄碱和可待因含量的方法, 并通过日间实验、柱间实验等对方法的稳定性进行了考察研究.胶束扫集电动色谱缓冲体系含60 mmol/L 十二烷基磺酸钠, 10 mmol/L NaH2PO4 (pH 2.20), 18%乙腈(V/V), 分离电压-14 kV, 测量波长200 nm. 讨论了pH、 SDS浓度、样品溶剂等对分离效果的影响. 在优化条件下, 麻黄碱和可待因均在5 min内出峰, 方法检出限(μg/mL)、线性范围(μg/mL)、相关系数分别为: 麻黄碱 0.433、 1.73～27.7、 0.9997, 可待因0.833、 3.33～50.3、 0.9996, 回收率在96.7%～103.5%之间. 峰面积日内RSD≤4.2% (n=5), 日间RSD≤8.0% (n=5), 柱间实验RSD≤2.3% (n=3).     

Large volume sample stacking capillary electrophoresis for metallothioneins analysis in eel liver

A large volume sample stacking procedure (LVSS) is developed here for metallothionein (MT) determinations in rabbit liver by using capillary electrophoresis with UV detection. A 10-time improvement in concentration-based LODs, when compared to the normal stacking mode (CE-UV analysis of samples solved in water), is achieved.The methodology is successfully applied to analysis of MTs in eel liver cytosolic extracts, preceded by an easy cleaning-up pre-treatment in order to eliminate the high salt content. Analysis of cytosol obtained from a group of eels previously exposed to Cd (induced group) resulted in several isoforms of MTs with differences in absorbance signal compared to a control group.     

Sample-stacking techniques in non-aqueous capillary electrophoresis

In sample-stacking techniques, the detection limit cannot be improved by simply increasing the length of the sample solution, because the individual electrophoretic parameters must be optimized. In an attempt to increase the amount of sample injected, as well as to focus them onto a small zone, two novel methods are proposed. One of these employs an "ultra-high conductivity zone", which was inserted between the sample zone and background solution to build an unequal conductivity gradient. The other employs a "low temperature bath". A portion of the capillary (near the junction between the sample solution and the background solution) was immersed in a low temperature bath, which served as a "pseudo-high-conductivity zone" due to the fact that conductivity would increases when the temperature is decreased. As a result, a large volume of sample injection can be achieved. Using 3,4-methylenedioxymethamphetamine as a model compound, the detection limit was determined to be 1.6 x 10(-6) M (S/N = 3) by means of normal non-aqueous capillary electrophoresis (NACE). This could be improved to 3.0 x 10(-8) M, 4.8 x 10(-9) M and 5.0 x 10(-9) M, respectively, when the normal stacking, ultra-high conductivity zone NACE-stacking and the low-temperature zone NACE-stacking methods were applied.