司帕沙星的毛细管电泳高频电导法测定

采用毛细管电泳高频电导法检测了司帕沙星。探讨了缓冲液的种类、浓度、添加剂以及操作电压和进样时间等因素对分离的影响。选择3.0mmol LHAc-5.0?H5OH(V V)为电泳介质,分离电压20.0kV,在4min内可实现司帕沙星的分离检测。在优化条件下,司帕沙星的线性范围为6 0～280 0μg mL,检出限为1 9μg mL。在该条件下,片剂中的敷料不干扰测定,可成功测定片剂中的司帕沙星,样品回收率为98.7%～101%。     

Evaluation of the detection of biomolecules in capillary electrophoresis by contactless conductivity measurement

The sensitivity of contactless conductivity detection to amino acids, peptides and proteins in CE was studied for BGE solutions of different pH values. The LOD and analytical characteristics were compared for acidic and basic conditions and better results were in most cases found for buffers of low pH values. Linear dynamic ranges varied between two orders of magnitude for amino acids and peptides and three orders of magnitude for larger proteins. The concentration detection limits were found to be between 1.2 and 7.5 microM for the amino acids tested and for the larger molecules they varied between 2.6 microM for leucine enkephalin and 0.2 microM for HSA when using a buffer at pH 2.1.     

Speciation of chromium (III) and chromium (VI) by capillary electrophoresis with contactless conductometric detection and dual opposite end injection

A sensitive, rapid and inexpensive capillary electrophoretic method for the determination of Cr(III) and Cr(VI) species is presented. The method is based on the dual opposite end injection principle and contactless conductometric detection. The sample containing cationic and anionic species is injected into the opposite ends of the separation capillary and after the high voltage is applied, the analytes migrate towards the capillary center, where the cell of a contactless conductivity detector is placed. The method does not require any sample pretreatment, except dilution with deionized water. The separation of Cr(III), Cr(VI) and other common inorganic anions and cations is achieved in less than 4 min. The parameters of the separation electrolyte solution, such as pH and concentration of L-histidine, were optimized. Best results were achieved with electrolyte solution consisting of 4.5 mM L-histidine, adjusted to pH 3.40 with acetic acid. The detection limits achieved for Cr(III) and Cr(VI) were 10 and 39 microg.L(-1), respectively. The repeatability of migration times and peak areas was better than 0.3% and 2.8%, respectively. The developed method was applied to the analyses of rinse water samples from the galvanic industry. The results for the determination of Cr(III) and Cr(VI) were in good agreement with the results obtained by certified differential spectrophotometric method using diphenylcarbazide (CN 83 0520-40) and with the results for the total chromium concentrations determined by electrothermal atomic absorbance spectrometry (ET-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS).     

Contactless Conductivity Detection in Capillary Electrophoresis: A Review

The popularity of contactless conductivity detection in capillary electrophoresis has been growing steadily over the last few years. Improvements have been made in the design of the detector in order to facilitate its handling, to allow easy incorporation into available instruments or to achieve higher sensitivity. The understanding of its fundamental working principles has been advanced and the detection approach has also been transferred to lab‐on‐chip devices. The range of applications has been extended greatly from the initial work on small inorganic ions to include organic species and biomolecules. Concurrent determination of cations and anions by dual injection from opposite ends has been demonstrated as well as sample introduction by using flow‐injection systems for easy automation of the process.     

毛细管电泳高频电导法测定苦参中的苦参碱和氧化苦参碱

建立了用毛细管电泳高频电导法测定苦参药材中苦参碱和氧化苦参碱的方法。对电泳介质的种类、浓度、pH值以及操作电压和进样时间对分离检测的影响进行了研究。缓冲液为2.0mmol LNa2HPO4 1.0mmol LH3PO4 体积分数为25%乙醇(pH6.0),分离电压为16.0kV时可实现较好的分离与检测。苦参碱和氧化苦参碱的线性范围为:25.0～1.00×103μg mL(相关系数分别为0 987和0.999);RSD(n=6)分别为:2.1%和0.70%;检出限分别为10.0和5.00μg mL;回收率分别为92.7%～99.1%和100%～102%。     

Determination of Proteinogenic Amino Acids in Human Plasma by Capillary Electrophoresis with Contactless Conductivity Detection

Capillary electrophoresis (CE) with contactless conductivity detection (CCD) represents a viable alternative to liquid chromatography in the analysis of amino acids (AA) in human plasma. After optimizing the composition of the background electrolyte (BGE), and introducing simple plasma pretreatment to remove spurious protein components, the CE/CCD methods allows determination of 18 from 20 proteinogenic AAs, three nonproteinogenic AAs and creatinine in 60 minutes. AAs are separated in their cationic forms in BGE containing 1.7 M acetic acid and 0.1% hydroxyethylcellulose, pH 2.2. LODs for individual AAs vary in an acceptable range with minimum of 4.3 μM for Arg and maximum of 42.9 μM for Cys. Mean concentrations and concentrations ranges for AAs in human plasma samples from 9 healthy individuals are found to agree well with those determined by an LC method in other two laboratories.     

Determination of different classes of amines with capillary zone electrophoresis and contactless conductivity detection

The use of contactless conductivity detection for the determination of different organic amines in CE was successfully demonstrated. Aliphatic non UV-absorbing species could be determined along absorbing compounds by measuring the conductivity of their protonated forms. The species tested included short-chained aliphatic primary, secondary and tertiary amines, branched aliphatic amines, diamines, hydroxyl-substituted amines as well as species incorporating aromatic and non-aromatic cyclic moieties. Highest sensitivity was obtained with BGE solutions containing solely acetic acid. A concentration of 0.5 M at a pH value of 2.5 was used. Detection limits were in the order of 1 microM. Complete separation of cis- and trans-1,2-diaminocyclohexane could be achieved by adding 18-crown-6 as modifier to the electrolyte solution.     

Formamide as solvent for capillary zone electrophoresis

A comprehensive investigation of a number of aspects when using formamide as background electrolyte solvent in capillary zone electrophoresis was presented. It included (i) the change of the ion mobility with ionic strength, (ii) the influence of the ionic strength on diffusion coefficients, and (iii) on the separation efficiency expressed by the maximum reachable plate numbers (when only longitudinal diffusion contributed to zone broadening), (iv) the effect of the solvent on pKa values (taken from the literature) of neutral and cation acids, (v) the establishment of the a pH scale in formamide by dissolving acids with known pKa values and their salts at defined proportion (thus circumventing the problem of calibrating the pH meter), (vi) the agreement between the experimentally derived and the theoretical dependence of the effective mobility on pH, (vii) the uptake of water of this hygroscopic solvent from the humidity of the environment and its consequence to the ion mobilities, pKa values, and the chemical stability of the solvent (e.g., hydrolysis), and finally (viii) the use of conductivity and indirect UV absorption to enable detection of analytes below the optical cutoff of formamide.     

Fast electrophoresis in conventional capillaries by employing a rapid injection device and contactless conductivity detection

A purpose-made set-up featuring an automated fast injector allowed the easy optimization of the injected amount and the adjustment of the separation length of conventional capillaries from a minimum of 5 cm upward. It was found that a compromise in capillary length for separation efficiency and analysis time also has to take into account the injected amount, which in turn affects the sensitivity and hence the detection limit. The versatility of the system was demonstrated by the analysis of the major cations and anions in natural water samples in less than 1 min, the concurrent determination of a mixture of amino acids and carbohydrates in 160 s, and of three active ingredients in a pharmaceutical preparation in 40 s. Plate numbers were typically around 50,000 and detection limits down to 1 M could be achieved.     

毛细管电泳高频电导法测定青风藤药材及制剂中青藤碱的含量

青藤碱（Sinomenine)是具有镇痛、消炎、怯风除湿、活血化瘀、增强免疫和抗癌等作用的生物碱单体(结构式见Scheme 1),它存在于防己科植物青风藤和毛青藤的干燥藤茎中,在临床上,已有正青风痛宁片、盐酸青藤碱注射液和毛青藤总片等制剂,用于治疗各种急慢性风湿痛、肿胀以及心率失常等病症．青藤碱含量测定常用非水滴定法,但该法专属性差,实验结果易偏高．此外,     

Carbon nanotube-enhanced separation of DNA fragments by a portable capillary electrophoresis system with contactless conductivity detection

It was demonstrated that separation of DNA fragments by a CE-contactless conductivity detection system (CE-CCD) could be enhanced with multiple-wall carbon nanotubes (MWCNs) as buffer additive. For HaeIII digest of PhiX174 DNA, optimized MWCN concentration was obtained when the MWCN was above its threshold concentration, at which MWCN could form a network in the buffer as pseudostationary phase to provide additional interaction sites. In the case of larger DNA, MWCN near or below its threshold concentration was enough to provide great improvement of the resolution, which was shown by the separation of the 2-Log DNA ladder. Furthermore, the buffer containing MWCN could provide a more stable baseline in the CE-CCD system, owing to less fluctuation of its conductivity. Compared with CE-UV, CE-CCD with MWCN could provide lower LODs as well as better resolution.     

毛细管电泳高频电导法测定几种中药中的丁香酚

在三乙胺的弱碱性体系中, 对几种不同产地中药中的丁香酚含量进行了测定, 结果显示这几种中药中的丁香酚含量存在明显的地区差异.     

毛细管电泳法快速测定五倍子中的没食子酸

建立了毛细管电泳高频电导法测定没食子酸的方法.探讨了缓冲溶液、有机溶剂添加剂、分离电压等因素对分离检测的影响.在电泳介质为10.0mmol/L Tris-5.0 mmol/L H3BO3-15.0?H5OH,分离电压22.0 kV的优化条件下,5.5 min内即可实现没食子酸的分析,线性范围为3.00～100 μg/mL,检出限为1.0 μg/mL.成功地检测了五倍子中的没食子酸.     

双氢青蒿素的毛细管电泳高频电导法测定

采用毛细管电泳高频电导法对双氢青蒿素的快速分离检测进行了研究。对电泳介质的种类、浓度、添加剂以及操作电压和进样时间等影响因素进行了优化。实验选择的最佳条件为：分离介质4．0mmol／L三乙胺-2．0mmol／LH3BO3-15．0％C2H5OH,分离电压22．0kV,20．0cm位差虹吸进样15．0s。在该实验条件下,可在5min内实现对双氢青蒿素的分离检测,双氢青蒿素的峰面积与含量在3．0～165μg／mL范围线性关系良好,检出限为1．0gg／mL。成功测定了双氢青蒿素片剂中的双氢青蒿素,回收率达98．0％～103％。该方法简便、快速、成本低,可用于药物分析。     

Capillary electrophoresis study on phase of mixed micelles and its role in transport phenomena of particles

In the present work comprehensive studies on electrophoretic effects induced by a phase of mixed micelles, that migrates surrounded with background electrolyte (BGE) and is denoted as the BGE/segment of mixed micelles/BGE system, were undertaken using capillary electrophoresis coupled with contactless conductivity or UV–vis detector. It was established that mixed micelles under electrophoresis are subject of evolution in terms of mobility, peak area and presence of sub-zones enforced by the composition of micellar phase, segment length and applied voltage. Established features allowed us to explain the electrophoretic behavior of nanoparticles in the system BGE/sample containing nanocrystals/segment of mixed micelles/BGE and it was postulated that a pseudomicellar state of nanoparticles can be useful term in analyzing the migration phenomena of nanoparticles within micellar environment. In contrast to the previous works, where transport of nanocrystals (NCs) within micellar segment or between two micellar segments was analyzed, the present work is focused on the transport of NCs from sample of NCs dispersed in BGE to phase of mixed micelles, i.e., to rear boundary between micellar zone and BGE. Based on these results, systematic studies on transport efficiency for nanoparticles in the system BGE/sample containing nanocrystals/segment of mixed micelles/BGE show that the system assures efficient transport of nanoparticles from BGE based sample to micellar phase and their efficient preconcentration at the micellar segment/BGE rear boundary.     

毛细管电泳场放大进样-高压非接触电导检测测定痕量Zn~(2+)

利用高压电容耦合非接触电导检测器(HV-C4D),结合毛细管电泳场放大进样(FASS),以2-N-吗啡啉乙磺酸(MES)/组氨酸(His)为缓冲溶液,电泳分离测定了Zn2+.考察了样品溶液中MES/His的浓度及电动进样时间对场放大浓缩因子及缓冲溶液浓度对检测灵敏度的影响.在10mmol/LMES/His(pH=4.9)的分离缓冲溶液中,FASS对Zn2+的浓缩因子为1.3×103.Zn2+的浓度在10～1000nmol/L范围内与峰面积有良好线性关系(R=0.9995),检测限为5nmol/L(S/N=3).该方法可用于痕量Zn2+的测定.     

Capillary electrophoresis with contactless conductivity detection for uric acid determination in biological fluids

The suitability of capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C⁴D) for the direct determination of uric acid in human plasma and urine was investigated. It was found that a careful optimization of the buffer composition and pH was necessary to achieve selective determination in the complex sample matrices. An electrolyte solution consisting of 10 mM 2-morpholinoethanesulfonic acid (MES), 10 mM histidine and 0.1 mM hexadecyltrimethylammonium bromide (CTAB), pH 6.0, was finally found suitable for use as running buffer for both sample matrices. The limit of detection (3 S/N) was determined as 3.3 μM. The linearity of the response was tested for the range between 10 and 500 μM and a correlation coefficient of 0.9996 was obtained. Intra- and inter-day variabilities were <10%. Quantitative analysis of urine and plasma samples showed a good correlation with the routine enzymatic method currently used at the University Hospital of Basel.