共查询到16条相似文献,搜索用时 125 毫秒
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微乳液电动色谱测定油-水分配系数的改进方法研究 总被引:1,自引:0,他引:1
通过考察微乳液电动色谱(MEEKC)中化合物浓度和高电场对其迁移行为的影响, 探讨了化合物分配于微乳后改变微乳内相性质的原因, 以及电泳高电场致使微乳液性质变化的机理. 在此基础上建立了一种测定化合物油-水分配系数的改进型MEEKC方法. 将此改进方法应用于烷基苯化合物之油-水分配系数的测定, 其测定值与文献参考值平均相差0.07个对数单位, 准确度较现行MEEKC方法有了明显提高. 相似文献
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建立了微乳液毛细管电动色谱(MEEKC)模式下,采用常规样品堆积模式(normal stacking mode, NSM)和反向极性堆积模式(reversed electrode polarity stacking mode, REPSM)两种在线富集邻苯二甲酸酯类化合物(phthalate esters, PAEs)的简便、有效方法。与常规MEEKC方法相比,REPSM-MEEKC方法使4种PAEs的检测灵敏度提高了937.5~7143倍。考察了常规MEEKC的分离条件,分别对影响两种富集过程的一些因素进行了研究,同时对两种富集方法的重现性和检出限等进行了考察。NSM-MEEKC和REPSM-MEEKC对邻苯二甲酸酯类化合物的检出限(按信噪比(S/N)=3计)分别为0.021~0.33 mg/L和0.7~4 μg/L。其中,灵敏度更高的REPSM-MEEKC方法已成功应用于食品塑料袋中邻苯二甲酸酯类化合物的测定,加标回收率为89.1%~105.6%,结果令人满意。 相似文献
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微乳电动毛细管色谱分离山酮类化合物的影响因素 总被引:7,自引:5,他引:2
在优化微乳系统(如pH、缓冲液浓度、表面活性剂、助乳剂、油相及添加剂)的基础上,对影响微乳电动毛细管色谱(MEEKC)分离山酮类化合物的因素进行了系统研究。以正辛醇-水分配系数(疏水常数log P)、色谱峰对称因子和理论塔板数作为参数,研究了分离条件的改变对MEEKC分离性能的影响。结果表明,色谱条件的改变对疏水性山酮和亲水性山酮分离选择性的影响存在着显著差异,当微乳体系为50 mmol/L硼酸缓冲液(pH 9.5)、10%(体积分数)正丁醇、80 mmol/L正庚烷、120 mmol/L十二烷基硫酸钠和 相似文献
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MicroemulsioneIectrokineticchromatography(MEEKC)isonekindofelectrokineticchromatography(EKC),whoseseparationprincipIeisbasedonthedifferentpartitionofsolutesbetweenthepseudostationaryphaseandthesurroundingaqueousphase.Usingmicroemulsionsolutionasthepseudostationaryphase,MEEKCshowsahighsolubilizationcapacityandseparationefficiency"'.Inthiswork,theretentionbehaviorsofalkylbenzenesinbothanionicandcationicsurfactantMEEKCsystemswereinvestigated.Theeffectsofco-surfactantandsurfactantonseparat… 相似文献
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微乳电动毛细管色谱在掌叶大黄指纹图谱上的应用 总被引:4,自引:0,他引:4
采用微乳电动毛细管色谱法(MEEKC)建立不同来源掌叶大黄的指纹图谱,为其质量控制提供依据。使用未涂层石英毛细管柱(75μm×65 cm,有效长度55 cm),采用的缓冲液为w(SDS)∶w(正丁醇)∶w(正辛烷)∶w(10 mmol/L硼砂溶液)=3.3∶6.6∶0.8∶89.3并通过添加10%的乙腈组成的O/W型微乳体系,分离电压18 kV,检测波长280 nm。结果通过聚类分析和相似度分析处理,14个掌叶大黄样品初步分为三类:道地药材,市售一般品和次品。本方法可用于掌叶大黄质量评价的有效手段,为MEEKC在中药指纹图谱研究中开辟了新的应用途径。 相似文献
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考察了用微乳液毛细管电动色谱(MEEKC)分离蛋白质时微乳液组成等不同因素对分离的影响,并与胶束电动色谱进行对比,探讨了其分离机理,为蛋白质的分离鉴定提供了一种有力的工具. 相似文献
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Separation of Biphenyl Nitrile Compounds by Microemulsion Electrokinetic Chromatography with Mixed Surfactants 总被引:1,自引:0,他引:1
SuXuanGONG TaoBO LanHUANG KeAnLI HuWeiLIU 《中国化学快报》2004,15(9):1063-1066
A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion electrokinetic chromatography (MEEKC) within 30 rain. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mlnol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showedremarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar electrokinetic chromatography (MEKC) method. 相似文献
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Separations of human urine by microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic capillary chromatography (MEKC) with respect to resolution, migration times and efficiencies were optimized and compared. The optimised MEEKC and MEKC methods were simple and fast, both of which are excellent characteristics for the complex separations required in clinical and biomedical studies. However, resolution in MEKC was significantly greater than in MEEKC although migration times were 30% faster for the optimised MEEKC method. In addition, a faster analysis method (short-end injection) specifically for routine screening purposes was also investigated. With both MEEKC and MEKC modes, this provided short separations (less than 4 min for urine) with no major compromise in resolution. In conclusion, we found that MEEKC offered no real advantage over MEKC for urine analysis. 相似文献
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Microemulsion electrokinetic chromatography (MEEKC) and solvent modified micellar electrokinetic chromatography (MEKC) were investigated with the goal of the rapid separation of complex heroin and amphetamine samples. The rapid simultaneous separation of 17 species of heroin, amphetamine and their basic impurities and adulterants was performed within about 10 min using MEEKC for the first time, whereas solvent modified MEKCs were unable to resolve all the components. The comparisons between MEEKC and solvent modified MEKC proved internal lipophilic organic phase in microemulsions played an important role in improving the separation performance with respect to efficiency. However, the role of internal lipophilic organic phase in MEEKC was disgusted at high concentrations of cosurfactant, and the separations of MEEKC and 1-butanol modified MEKC became similar at high concentrations of 1-butanol. The evaluation of reproducibility, linearity and detection limit of optimized MEEKC method provided good results for all the analytes investigated, thus allowing its application to real controlled drug preparation analysis. 相似文献
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The elution order of the hop α- and β-acids has been studied under different modes of electrokinetic separation. A model is advanced to explain the shorter migration times of the more hydrophobic β-acids compared to the α-acids in micellar electrokinetic chromatography (MEKC). For quality control of the bitter principles in hops, the ruggedness of electrokinetic separation could be improved by replacing MEKC by microemulsion electrokinetic chromatography (MEEKC). 相似文献
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以大豆磷脂为主要的表面活性剂,制备适合毛细管电动色谱使用的不同构成比的微乳体系, 应用溶剂化参数模型研究了中性溶质在其中的定量结构保留关系.使用动态涂层毛细管, 以二甲基亚砜和十二烷基苯分别作为电渗流和微乳液滴迁移的标记物, 测定了26个具有不同结构小分子中性化合物在17种微乳电动色谱体系下的保留因子, 建立了线性溶剂化能量关系(LSER)方程.通过比较两体系的LSER方程系数比较体系相似性.结果表明, 本研究建立的磷脂微乳电动色谱体系在线性溶剂化特征上和其它构成的微乳电动色谱体系相似.对溶质保留贡献较大的是溶质体积和有效氢键碱度, 油相种类及浓度对溶质的保留选择性无明显影响. 相似文献
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Microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatograpy (MEKC) were compared for their abilities to separate and detect ten similar benzophenones, which are commonly used as UV filters in various plastic and cosmetic products. Sodium dodecyl sulfate (SDS) concentration and column temperature rarely affected separation resolution for MEEKC, but separation of benzophenones could be improved by changing the SDS concentration and column temperature for MEKC. Buffer pH and ethanol (organic modifier) were found to markedly influence the separation selectivity for both MEEKC and MEKC systems. In addition, a higher electric voltage improved the separation efficiency without a noticeable reduction in separation resolution for MEEKC, whereas it caused a poor separation resolution for the MEKC system. 相似文献
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In this study, microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatography (MEKC) were compared for their abilities to separate and detect thirteen phenolic compounds (syringic acid, p-coumaric acid, vanillic acid, caffeic acid, gallic acid, 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, (-)-epicatechin, and (-)-gallocatechin), and two other ingredients (caffeine and theophylline) in teas and grapes. Separation of phenolic compounds was improved by changing the SDS concentration for MEEKC, but the SDS concentration rarely affected the resolution for MEKC. Organic modifier (acetonitrile or methanol) was found to markedly influence the resolution and selectivity for both MEEKC and MEKC systems. In addition, a higher voltage and a higher column temperature improved the separation efficiency without any noticeable reduction in resolution for MEEKC whereas they caused a poor resolution for the MEKC system. Although separations with baseline resolution were achieved by the optimized MEEKC and MEKC methods, the separation selectivity resulting from the proposed MEEKC method was completely different from that of MEKC. 相似文献