基于复合型微流控芯片的紫外检测毛细管电泳系统

提出了一种基于芯片-毛细管复合装置的紫外检测-微流控芯片毛细管电泳分析系统.采用小死体积的耦合技术实现了石英毛细管与“十”字通道型微流控玻璃芯片的耦合.本系统的紫外检测灵敏度与商品化毛细管电泳仪相当.采用夹流进样方式,达到较高的进样重现性,2mmol/L苯甲酸的峰高相对标准偏差(RSD)为1.5%(n=11).可用于复方磺胺甲唑片剂的两种有效成分的快速分离.     

改良聚酰胺吸附-高效毛细管电泳内标法测定饮料中的亮蓝和苋菜红

以日落黄为内标物,建立了碳酸饮料中亮蓝和苋菜红的高效毛细管电泳内标测定方法。毛细管有效长度40 cm,内径75 μm,分离电压20 kV,进样量14 kPa×3 s,室温下分离,缓冲溶液为10 mmol/L磷酸氢二钠(pH 8.56),检测波长390 nm。亮蓝与苋菜红的相对校正因子分别为0.8329(相对标准偏差(RSD)为3.3%)和1.2253(RSD为2.6%);定量限(S/N=10)分别为1.629 mg/L和4.160 mg/L;回收率分别为97.87%～102.1%(RSD为1.8%)和94.07%～103.8%(RSD为4.1%);方法的精密度分别为3.2%和2.0%。对样品预处理的优化使该法更适用于碳酸类饮料中亮蓝和苋菜红的高效毛细管电泳分析。以样品空白为基液进行内标法定量测定,基本上消除了背景带来的系统误差。将该方法应用于实际样品的测定,结果准确。     

小型可连续进样微流控芯片分析的研制

报道了一种结构简单、可连续进样的小型控芯片分析仪的研制.顺序注射分析系统通过芯片上制作的接口将试样连续引入芯片,并采用自行设计的紧凑型光纤式激光诱导荧光检测器进行检测.该仪器用于芯片毛细管电泳分离实验室合成Cy5荧光染料,实现了连续进样和换样.峰高RSD为1.9%(n=11),试样通量35/h;相邻试样携出＜4%.     

基于PMMA毛细管电泳芯片的多位点突变检测研究

利用基于激光诱导荧光(LIF)检测的芯片毛细管电泳平台,批量制作了低成本聚甲基丙烯酸甲酯(PMMA)芯片,通过修饰管道,优化有效分离距离、分离介质等条件,可在90s内完成DNA片段的分离检测,实现单碱基分离,并在此平台上成功地对遗传性耳聋三个常见突变位点实现分型检测,为这种低成本的PMMA芯片应用于分型相关的临床诊断领域奠定了基础。     

微量金属元素的毛细管电泳分析方法及应用

综述了毛细管电泳分析微量金属元素的基本原理、分离模式(CZE、MKEC、非水电泳、芯片分离等)、检测方法(紫外、荧光、化学发光、安培、电导、质谱联用技术)等的进展和该技术在环境、生物医学领域的研究与应用。引用文献94篇。     

基于液芯波导原理的微流控芯片长光程光度检测系统

提出了一种基于液芯波导(Liquidcorewaveguide,LCW)原理的微流控芯片吸收光度检测系统.通过芯片与外界接口技术实现液芯波导管与芯片的耦合,建立了芯片上长光程(毫米至厘米级)吸收光度检测池.采用邻菲啉-铁(Ⅱ)显色体系验证系统分析性能,以5.5cm外覆TeflonAF液芯波导管作为检测池(检测池体积240nL)时,芯片系统的检测线性范围为0.03～50μmol/L,对邻菲啉-铁(Ⅱ)配合物的检出限为8nmol/L,检测池有效光程达1.7cm,分析精度RSD(n=5)为0.8%.     

聚甲基丙烯酸甲酯微流控分析芯片的简易热压制作法

提出聚甲基丙烯酸甲酯(PMMA)微流控分析芯片的一种简易热压制作法,研究了镍基、单晶硅和玻璃3种阳模制备芯片及芯片的封合条件.采用扫描电镜(SEM)和电荷耦合检测器(CCD)对PMMA芯片的微通道及其横截面形貌进行了表征.SEM图和CCD图表明实现了热压封接.测定了PMMA芯片的伏安曲线和电渗流,其电渗流值与文献报道值基本一致.本法制作的PMMA芯片用于电泳分离Cy5荧光染料,峰高RSD为2.2%(n=11),理论塔板数7.4×10⁴m^-1.     

高效毛细管电泳间接紫外检测血浆中钾、钙、镁

用高效毛细管电泳法,在pH 5.5的缓冲介质中用酒石酸作为络合剂,使血浆中钾、钠、钙、镁4种阳离子达到很好分离,用咪唑作为背景试剂进行了紫外检测.对电泳分离及紫外检测的各分析条件(包括背景缓冲溶液的pH值,咪唑溶液的浓度及酒石酸溶液的浓度等)作了试验并予以优化,上述4种离子的相互分离在4.5 min内顺利完成.文中给出了K 、Ca 、Mg2 的线性回归方程,其相关系数在0.998 4～0.999 4之间,证明了在各离子的峰面积与其浓度之间呈线性关系,3种离子的检出限(S/N=3)依次为0.20,0.12,0.06 mg·L-1.用迁移时间检测和用峰面积检测所得的RSD值(n=6)依次小于0.76%和2.83%.由于钠离子的吸收峰与系统峰重叠,钠的测定无法进行.回收率试验的结果在95.3%至104.2%.     

小型可连续进样微流控芯片分析仪的研制

报道了一种结构简单、可连续进样的小型微流控芯片分析仪的研制。顺序注射分析系统通过芯片上制作的接口将试样连续引入芯片 ,并采用自行设计的紧凑型光纤式激光诱导荧光检测器进行检测。该仪器用于芯片毛细管电泳分离实验室合成Cy5荧光染料 ,实现了连续进样和换样。峰高RSD为 1 .9% (n=1 1 ) ,试样通量 3 5 h ;相邻试样携出 <4%。     

毛细管气相色谱/原子吸收联用技术中卧管式微火焰原子化离子化同步检测器性能的改进和自动控温零死体积传输线的研制

报告了毛细管气相色谱 原子吸收联用技术研究中对卧管式微火焰原子化离子化同步检测器性能的改进和零死体积传输线的研究成果。在已有研究基础上 ,对卧管式微火焰原子化离子化同步检测器T型玻璃管及卧式长管不锈钢收集极的物理尺寸及相关操作条件进行了最佳化研究 ,同时 ,在T型玻璃管两端安装了石英玻璃窗 ,稳定了管内气流 ,改善了敏感度。二乙基汞原子化敏感度为 1 .4× 1 0 - 1 2 g s,线性范围 4 .2× 1 0 2 ,峰面积重现性 (RSD) 1 .7% ;苯离子化敏感度为 3 .5× 1 0 - 1 1 g s,线性范围 4 .0× 1 0 5,峰面积重现性 (RSD) 1 .5 %。研制了自动控温零死体积传输线 ,基本消除了由于传输线死体积中分子扩散导致的分辨率损失 ,顺利实现了毛细管色谱柱与卧管式微火焰原子化离子化同步检测器的连接。     

A sheathless poly(methyl methacrylate) chip-CE/MS interface fabricated using a wire-assisted epoxy-fixing method

Using a wire-assisted epoxy-fixing method, a sheathless CE/MS interface on a poly-(methyl methacrylate) (PMMA) CE chip has been developed. The sheathless chip-CE/MS interface utilized a tapered fused-silica tip and the electrical connection was achieved through a layered coating of conductive rubber. The wire-assisted method provided facile alignment of channels between the PMMA CE chip and an external capillary sprayer without the need for micromachining. Because the wire was in the channel during fixing, the risk of channel blockage by the epoxy was avoided. This chip CE device has minimal dead volume because the interstitial spaces were filled by a fast-fixing epoxy resin. The performance of the chip-CE-ESI-MS device was demonstrated with the analysis of peptide mixtures.     

螺旋通道微流控PCR芯片连续自动扩增DNA片段的研究

研制了由内向外流动的螺旋通道微流控PCR玻璃芯片,减少了PCR反应液在微通道中流动时的分散和阻力;讨论了扩增循环数和进样速度对长片段基因扩增的影响,在26min内成功扩增了质量浓度仅为10ng/mL的6012bpλ-DNA;通过将小孔径石英毛细管作为顺序注射(SI)系统的连接管路,使其死体积降到0.30μL.实现了微升级样品的自动换样、连续PCR扩增和微通道洗涤等功能.样品间无交叉污染.每小时可扩增500bpλ-DNA试样7个.扩增产物片段大小和荧光强度的相对标准偏差分别为0.4%和6.7%.     

Novel microfabricated device for electrokinetically induced pressure flow and electrospray ionization mass spectrometry

A novel microchip device for electrospray ionization has been fabricated and interfaced to a time-of-flight mass spectrometer. Fluid is electrokinetically transported through the chip to a fine fused-silica capillary inserted directly into a channel at the edge of the device. Electrospray is established at the tip of the capillary, which assures a stable, efficient spray. The electric potential necessary for electrospray generation and the voltage drop for electroosmotic pumping are supplied through an electrically permeable glass membrane contacting the fluidic channel holding the capillary. The membrane is fabricated on the microchip using standard photolithographic and wet chemical etching techniques. Performance relative to other microchip electrospray sources has been evaluated and the device tested for potential use as a platform for on-line electrophoretic detection. Sensitivity was found to be approximately three orders of magnitude better than spraying from the flat edge of the chip. The effect of the capillary on electroosmotic flow was examined both experimentally and theoretically.     

Reduction in sample injection bias using pressure gradients generated on chip

Sample injection in microchip-based capillary zone electrophoresis (CZE) frequently rely on the use of electric fields which can introduce differences in the injected volume for the various analytes depending on their electrophoretic mobilities and molecular diffusivities. While such injection biases may be minimized by employing hydrodynamic flows during the injection process, this approach typically requires excellent dynamic control over the pressure gradients applied within a microfluidic network. The current article describes a microchip device that offers this needed control by generating pressure gradients on-chip via electrokinetic means to minimize the dead volume in the system. In order to realize the desired pressure-generation capability, an electric field was applied across two channel segments of different depths to produce a mismatch in the electroosmotic flow rate at their junction. The resulting pressure-driven flow was then utilized to introduce sample zones into a CZE channel with minimal injection bias. The reported injection strategy allowed the introduction of narrow sample plugs with spatial standard deviations down to about 45 μm. This injection technique was later integrated to a capillary zone electrophoresis process for analyzing amino acid samples yielding separation resolutions of about 4–6 for the analyte peaks in a 3 cm long analysis channel.     

A new two-chip concept for continuous measurements on PMMA-microchips

A new concept for continuous measurements on microchips is presented. A PMMA (polymethylmethacrylate) based capillary electrophoresis chip with integrated conductivity detection is combined with a second chip, which undertakes the task of fluid handling and electrical connections. The combination of electrokinetic and hydrodynamic flows allows long-term continuous stable analyses with good reproducibilities of migration time and peak heights of analytes. The two-chip system is characterized in terms of stability and reproducibility of separation and detection of small ions. Relative standard deviations of <1% and 3% respectively for retention times and peak heights during long-term measurements can be achieved. The new system combines simple handling and automated analysis without the need for refilling, cleaning or removal of the separation chip after one or several measurements.     

Miniaturized thin-layer radial flow cell with interdigitated ring-shaped microarray electrode used as amperometric detector for capillary electrophoresis

A chip-type thin-layer radial flow cell was developed as an amperometric detector for capillary electrophoresis. We fabricated a carbon film-based interdigitated ring-shaped array (IDRA) microelectrode with a 2 microm bandwidth and an almost 1 microm gap on a glass plate and used it as a working electrode. A fused-silica capillary was arranged above the IDRA electrode using a guide hole drilled through the acryl plate that formed the flow cell lid. A flow channel for use in connecting the outlet capillary was also fabricated in the acryl plate. We characterized the analytical performance of the IDRA electrode in the microchip flow cell in terms of linear concentration range, sensitivity and concentration detection limit. We achieved a collection efficiency and catechol redox cycle at the IDRA microelectrode of 65% and 1.71, respectively, and thus a high sensitivity and low detection limit of 392.9 pA/microM and 15 nM for dopamine hydrochloride. We examined the reproducibility of the detector and found that the run-to-run and detector-to-detector relative standard deviations were both less than 10%.     

Dermal nitrate: an old marker of firearm discharge revisited with capillary electrophoresis

The present work describes a capillary electrophoretic method for nitrite and nitrate determination to be used as a screening tool for investigating the residues of firearm discharge. The use of capillary electrophoresis allowed the rapid determination of nitrite and nitrate, which are major inorganic components of gunshot residues, offering a quantitative and selective alternative to the traditional paraffin test (dermal nitrate test). The method is simpler, cheaper, and faster than the modern approaches to gunshot residue analysis based on the determination of barium, lead and antimony by using flameless absorption spectrometry, inductively coupled plasma-mass spectrometry (ICP-MS), or scanning electron microscopy. The analysis was carried out in a bare fused-silica capillary (75 microm inner diameter) with a 100 mM borate buffer (pH 9.24). The detection was by UV absorption at 214 nm. Separation took place under reversed voltage of 15 kV. Bromide was used as the internal standard. Sensitivity was about 1 mM for both nitrite and nitrate. Reproducibility (intraday and day-to-day) was also good with relative standard deviations (RSDs) < 1.0% for relative migration times and < 4.5% for peak areas in both standard solutions and real matrix. Hair and skin samples from a victim shot in the head were successfully analyzed for the presence of nitrite and nitrate.     

Separation of living and dead polymers in synthetic polypeptide mixtures by nonaqueous capillary electrophoresis using differences in ionization states

The complexity in the mechanisms of polymerization of N-carboxyanhydrides requires the development of new analytical techniques able to separate mixtures of synthetic polypeptides. This work focuses on the separation of poly(N(epsilon)-trifluoroacetyl-L-lysine) (PTLL) mixtures by nonaqueous capillary electrophoresis (CE). The main goal of this work was to find electrophoretic conditions that permit the separation and the quantification of the dead polymer families that were previously identified in the samples. The influence of the pH of the electrolyte on the selectivity of the separation was carefully investigated. The mechanisms of separation of the PTTLs are discussed as a function of their ionization state. The separations obtained on a noncovalently coated capillary were compared with those obtained on a fused-silica capillary. Finally, using two different electrolytes, it is possible to quantify the three families of PTLLs, namely, the living PTLLs, the dead PTLLs with N-formyl end group and the dead PTLLs with a carboxylic end group. These results confirm the importance of CE for the separation of synthetic organic polymers in nonaqueous electrolytes.     

Consecutive Electrophoretic Separation of PCR Products Under a High-Ionic-Strength Solution on PMMA Chips with Enhanced Static Adsorptive Coat

Abstract

Consecutive polymerase chain reaction (PCR) product electrophoretic separation was done using a high-ionic-strength solution on poly(methyl methacrylate) (PMMA) micofluidic devices. Microchannels were modified with an enhanced static adsorptive coating method using 3% hydroxyethyl cellulose. The relative standard deviations of migration time and fluorescence intensity for the amplified cytosine deaminase PCR product of 258 bp (without pretreatments in 16 consecutive and rapid runs) on the PMMA chip were 0.88% and 3.5%, with a separation efficiency of 6.0 × 10⁵/m. PCR products were repeatedly separated on the modified chip without rinsing the channels with water and refilling the channels with the sieving matrix between runs.