Determination of the pKa of Benzophenones by Capillary Zone Electrophoresis

Electrophoretic behavior of seven benzophenones as a function of the buffer pH was investigated, and their pK_a values were determined by capillary zone electrophoresis. The determination of pK_a allows us to rationalize the influence of the buffer pH on the migration behavior of benzophenones. The results reveal that both the presence of intramolecular hydrogen bond and the favorable π‐electronic delocalization decrease the degree of the acid dissociation of the hydroxyl groups of hydroxybenzophenones. However, the introduction of a hydroxyl group at the 4‐position or at the 2′‐position of the aromatic ring of hydroxybenzophenones would decrease greatly their pK_a1 values. Thus the presence of this type of hydrogen bonding also plays an important role in the acid dissociation of these hydroxybenzophenones.     

Separation and Determination of Bases by Capillary Zone Electrophoresis

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毛细管区带电泳分离硝基苯胺位置异构体的研究

采用毛细管区带电泳(CZE)技术,在极端pH值条件下分离了邻、间、对硝基苯胺位置异构体;研究了背景缓冲溶液、pH值、分离电压、温度及进样时间等因素对分离的影响,得出了3种样品的标准曲线、线性范围及加样回收率。在选定的实验条件下15min内实现了上述3种苯胺类化合物的分离。该方法快速,准确,重现性好。     

九种嘌呤碱的毛细管区带电泳分离

用毛细管区带电泳法分离和测定咖啡碱，９－Ｎ二羟丙基茶碱，可可碱，腺嘌呤，鸟嘌呤、茶碱、黄嘌呤、尿酸和６－巯基嘌呤，在熔硅毛细管（７０ｃｍ×７５μｍｉ．ｄ，有效长度６３ｃｍ）内，使用０．０１ｍｏｌ／Ｌ（ｐＨ＝１０）硼砂缓冲溶液，电压为２５ｋＶ温度为３０℃，真空进样１ｓ，于２６０ｎｍ处检测，可在７ｍｉｎ内分离上述到９种嘌呤碱，理论塔板数达到３．０×１０＾５，检测限达ｆｍｏｌ级，方法用于人尿分析，结果令     

几种标准蛋白质的毛细管区带电泳的分离及其迁移行为

本文采用毛细管区带电泳分离了几种标准蛋白,研究了不同的清洗方式,不同ＰＨ的缓冲溶液等对迁移行为及分离的影响,并同时考察了迁移时间和相对迁移时间与操作电压的关系。     

毛细管区带电泳分离和测定嘧啶碱

本报道毛细管区带电泳分离和测定胞嘧啶，胸腺嘧啶，尿嘧啶，羟乙基氟尿嘧啶，尿嘧啶丙酸和５－氟尿嘧啶，在熔硅毛细管（７０ｃｍ×７５μｍｉ，ｄ，有效长度６３ｃｍ）上，以０．０１ｍｏｌ／Ｌ硼砂缓冲溶液（ｐＨ＝９．２５）作电解质，电压为２０ｋＶ，温度为３５℃，真空进样１ｓ，于２７０ｎｍ处检测，可在８ｍｉｎ内完全分离上述６种嘧啶碱，塔板数达到２．５×１０＾５，碱基检测限为（０．９～３．６）×１０＾－６ｍｏｌ     

砷酸根和硒酸根的毛细管电泳分离

在铬酸盐和硼酸盐溶液中,以十六烷基三甲基溴化铵(CTAB)为电渗流改性剂,通过添加有机添加剂甲醇,成功地分离了砷酸根、硒酸根及常见酸根离子。优化分离条件发现,采用210 nm直接检测砷酸根比在260 nm处间接检测其检出限更低,而且可以减少大量C l-的干扰。迁移时间重复性的相对标准偏差(RSD)不大于3.0%,当信噪比(S/N)为2时,在260 nm处,HAsO42-与SeO42-的检出限分别为0.019 mg/L和0.078mg/L;在210 nm处,HAsO42-检出限可达0.004 3 mg/L。加标回收率均在95%~108%之间,满足定量要求。但NO3-会干扰HAsO42-的定量分析。     

毛细管区带电泳电化学检测器

本文阐述了毛细管区带电泳探针式安培检测器的构造、工作原理、理论及其与电泳系统的联结技术;介绍了该检测器的应用情况。     

郁金中姜黄素类化合物的毛细管区带电泳法测定

本文在提取中药郁金中姜黄素类化合物的基础上,利用毛细管区带电泳法对郁金中所含黄素类化合物进行了分离研究,确定了最佳分离条件:9mmol/L单-6-O-苯基氨甲酰基-β-CD(mono-6-O-phenylcarbamoyl-β-CD),40mmol/L硼砂缓冲液,分离电压为15kV,毛细管柱温度为22℃,紫外检测波长为214nm,pH值为9.0。双去甲氧基姜黄素、去甲氧基姜黄素和姜黄素在此条件下10 m in内能够达到基线分离,方法快速、简便、且消耗试剂少,不污染环境。     

毛细管区带电泳中的pH效应

毛细管电泳是在电场作用下带电粒子在毛细管内的定向移动。溶质在给定时间间隔和给定电场下移动的距离用淌度表示,而淌度受到缓冲液pH的影响显著,因此,确定缓冲液、选择并控制其pH值是毛细管电泳技术的关键。本文对pH值对淌度的影响进行了研究。 1 实验部分 所有实验在HPE-100毛细管电泳仪(Bio-Rad USA)上进行,紫外检测,电动进样。所用毛细管柱中S柱由Bio-Rad提供,H_5、H_6和E均为本实验室自行制备,研制过程和性能考察     

Separation of Hydroxybenzoic Acid Isomers by Capillary Zone Electrophoresis

Abstract

Capillary zone electrophoresis is a highly efficient analytical technique that has been shown to be particularly useful for the analysis of isomers. Using a cathodic injection and anodic detection scheme, ortho-, meta- and para-hydroxybenzoic acids were separated in a fused-silica capillary column with a phosphate buffer at pH 10.3 (25.0 mmol/1 phosphate + 0.20 mmol/1 cetyltrimethylammonium bromide (CTAB) + 10% (v/v) 1-propanol with an applied voltage of 10 KV followed by direct UV detection. The use of CTAB as electroosmotic flow modifier allows the rapid separation of the three isomers by reversing the direction of electro-osmotic flow. The influence of pH, CTAB concentration and organic solvents on the migration behaviour of the solutes were also studied.     

Chiral Separation of Esmolol and Terazosin by Cyclodextrinmodified Capillary Zone Electrophoresis

IntroductionTheincreasingnecessity0fpharmacologicalresearchforchiraldrugshasrenderedchiralseparationanactiveareaincaPillaryelectroph0resis(CE)today.Variousmodes0fCE,includingcaPillaryzoneelectroph0resis(CZE),micellarelectrokineticchromatography(MEKC),caPillarygelelectrophoresis(CGE)andcapillaryisotachophoresis(CITP),havebeenappliedforthispurp0se',amongwhichCZEisthemostpopularoneforitshighefficiency,lowexpenseandeaseofoperation.Forsuccessfulchiralseparati0ninCZE,theselectortypeisofcr…     

Separation and Migration Behavior of Dichlorophenols in β‐Cyclodextrin‐Modified Capillary Zone Electrophoresis

The separation and migration behavior of six isomeric dichlorophenols (DCPs) in cyclodextrin‐modified capillary zone electrophoresis (CD‐CZE) using a phosphate‐borate buffer at alkaline pH with β‐CD and hydroxypropyl‐β‐CD (HP‐β‐CD) as electrolyte modifiers were investigated. The influence of buffer pH and the concentration of β‐cyclodextrins were examined. The results indicate that baseline separation of six isomeric DCPs can be achieved with addition of β‐CD concentration in the range of 2.0‐10 mM or HP‐β‐CD concentration in the range of 4.0‐10 mM at pH 10.0. Binding constants of DCPs to β‐CDs were evaluated for a better understanding of the interaction of DCPs with β‐CDs.     

毛细管区带电泳的离子交换在柱预富集技术研究

提出了离子交换固相萃取的毛细管区带电泳在柱预富集技术。预富集毛细管和分离毛细管的端面靠紧,二者通过一段带侧孔的聚四氟乙烯（PTFE）套管固定。预富集毛细管内壁键合羧基阳离子交换基团,进样时分析离子被保留在预富集管的固定相上,用2mol／L的氯化铵溶液洗脱,再进行毛细管区带电泳分离。方法成功富集和分离了两种低浓度的药物阳离子,普萘洛尔和美托洛尔的灵敏度比常规电动进样分别提高4200和3400倍,其浓度检出限分别为0．02μg/L和0．14μg/L。     

毛细管区带电泳同时分离苯二酚和硝基苯酚位置异构体

运用毛细管区带电泳模式,通过在缓冲溶液中添加有机溶剂成功地分离了邻、间、对苯二酚和邻、间、对硝基苯酚两组位置异构体。研究了缓冲溶液种类、浓度、pH值、电泳电压、温度、进样时间及有机溶剂等因素对分离的影响,得出了6种样品的标准曲线、线性范围及加样回收率。在优化条件下,10min内实现了上述6种酚类化合物的分离。该方法简便、快速、重现性好。     

毛细管电泳分离氯代酚的研究

用毛细管区带电泳方法进行了氯代异构体分离的研究。使用６４．５ｃｍ×５０μｍ．Ｉ．Ｄ。石英毛细管柱，在４０％有机溶剂改性的磷酸盐缓冲溶液中，通过调节最佳ＰＨ值，达到了一次进样对所有氯代酚的基线分离。     

毛细管区带电泳法对柱前衍生胆汁酸的高效分离研究

以7-氨基-1,3-萘二磺酸作为柱前衍生试剂,采用毛细管区带电泳-光二极管阵列检测器分离测定6种胆汁酸。实验综合考察了缓冲溶液浓度、pH值、温度及添加剂对胆汁酸衍生化产物分离效果的影响。在不加其它添加剂情况下,于25mmol/L的pH为9.5的硼酸盐缓冲溶液中,20℃,5kPa压力下进样,进样时间8s,13min可实现6种胆汁酸的快速高效基线分离。该方法检出限(3σ)为0.022～0.046μmol/L,线性范围为0.07～5μmol/L。