矩形截面毛细管电泳和二维分离

在石英单晶表面制成矩矩截面毛细管柱中进行电泳实验。由于矩形柱比圆形柱有更大散热侧面积且石英单晶的导热性能远无于熔融石英，所以可施加较高的场强，不仅提高了柱效，而且缩矩了分离时间。两相交的通道之间形成自然连接，可实现二维分离，并消除死体积。     

用毛细管色谱法分析14种拟除虫菊酯立体异构体

用石英毛细管柱分离了14种拟菊酯的立体异构体。柱1用QF-1固定液10m×0.53mm×1.0μm膜厚,柱温在180℃～260℃之间,可完全分离右旋丙炔菊酯等10种拟菊酯的立体异构体。往2为HP-525m×0.53mm×1.0μm膜厚,用合适的住温可分离百治菊酯等4种拟菊酯的异构体。     

纳米管钛酸多孔层石英毛细管色谱柱的制备及热处理对色谱保留性能影响研究

在实验室合成了具有较大比表面积和纳米管特性的纳米管钛酸H2Ti2O4(OH)2,对其热处理前后的形貌和结构进行了表征,将其作为气—固色谱吸附剂制备出一种新型纳米管钛酸石英PLOT柱,同时考察了这种纳米管结构的钛酸作为固定相对C1—C4气体烷烃混合物、空气和SF6以及CO和CO2的分离性能。结果表明：新型纳米管钛酸石英PLOT柱具有特殊的吸附分离性能,纳米管钛酸作为气—固吸附色谱石英毛细管柱的固定相,对C1-C4烷烃具有较强的吸附性、较好的峰对称性和较高的分离度,而且能够分离CO和CO2以及空气和SF6等永久性气体组分。在150℃、-0．1MPa真空下对纳米管钛酸处理后,其形貌、结构和表面性质均发生变化,将对C1-C4烷烃分离的保留时间(tR′)和色谱峰对称性(Tf)产生影响,在300℃,N2气氛下处理后,纳米管特性完全消失,其不适宜再作分析C1-C4烷烃的固定相。     

对甲苯磺酸三甲胺固定相的研究及其分析应用

采用汞塞动态法涂柱,以对甲苯磺酸三甲胺作为固定液制备了石英毛细管色谱柱,固定液量为9.0%(m/V),柱尺寸为30 m×0.32 mm i.d.。对该柱的性能进行了考察。实验结果表明,这种色谱固定相对于极性有机化合物如醇类物质、有机羧酸、酚类物质等有良好的分离能力,且出峰快,时间短,峰形窄而对称。     

毛细管气相色谱测定胶原蛋白和卵清蛋白氨基酸

讨论了纳克量级(ppb)的18种氨基酸在石英毛细管住气相色谱的分离和定量测定。用此法对胶原蛋白和卵清蛋白水解氨基酸进行了定量。结果的精确度为0.8～7.3%。氨基酸的衍生化采用N-TFA-butyl系统,分二步完成,第一步在酸性介质中用亚丁醇酯化;第二步是用三氟醋酐酰化。氨基酸回收率在85%以上。蛋白质水解在6N恒沸点盐酸中充氮气,在145±2℃加热4小时完成。     

对空气敏感的金属有机化合物单晶取样新技术

单晶的取样技术直接关系到晶体能否准确进行X-射线结构测定的成败。对空气及湿气极为敏感的金属有机化合物,特别是稀土金属有机化合物,本身的合成、分离、纯化、分析和单晶     

石英微米晶粒电泳微柱的制备及其电泳分离

研究了内径2 mm石英管填充均匀石英微米晶粒的电泳微柱制备及其电泳分离的可行性.石英微米晶粒用水热法合成.含30%甲醇的1.5 mmol/L Na2HPO4为电泳缓冲液(pH 11.5),对无需衍生的色氨酸、苯丙氨酸和酪氨酸进行了微柱电泳分离和紫外吸收检测.检出限分别为0.038、 0.21和0.20 μmol/L; 色氨酸的分离效率为4.4 × 104塔板数/m,电泳微柱的样品容量达到35 μL, 且有较好的分离重现性.对未填充石英微粒, 填充平均粒度360 μm石英砂和长9 μm石英微米晶粒的电泳微柱的热效应进行了讨论.实验结果表明,在电泳微柱中填充石英微米晶粒可抑制大柱径电泳的热效应,增大样品容量,提高检测灵敏度.此微柱电泳技术可作为现场、实时和便携式电动流动全分析系统的高效分离手段,适合大体积和低浓度样品分析.     

用三维虚拟技术突破手性结构的教学瓶颈——以α-石英的手性结构为例

针对中学化学“物质结构与性质”模块3个版本教材中有关石英结构的二维图形不利于教学的局限性，利用“晶体学开放数据库”数据制作α-石英晶体结构三维虚拟模型，借助三维虚拟技术强大的交互功能全方位探索α-石英的空间结构，展示α-石英独特的大半径双螺旋手性结构，揭秘其旋光性的原因。教学实践表明，利用三维虚拟技术拓展中学结构教学的广度和深度是可行的。     

肉类制品中微量锶的分离及^87Sr/^86Sr同位素比值测定

利用87Sr/86Sr同位素比值进行生物和古人类源区与迁徙的示踪是Sr同位素技术应用的新领域,也是考古研究和肉类食品溯源研究的新尝试。本研究对牛肉干粉采用酸溶、微波消解和灰化后硝酸提取等不同方法进行消解,比较了它们的离子交换分离效果和Sr同位素测定结果;用石英、石墨和瓷坩埚3种器皿对牛肉干粉进行灰化,检测了灰化器皿对87Sr/86Sr同位素比值的影响,从而确定了石英坩埚灰化的消解方法,建立了适合于肉类制品微量Sr的化学分离方法与87Sr/86Sr同位素比值测定方法。本方法包括肉类制品的石英坩埚灰化、离子交换分离和87Sr/86Sr比值的热离子化质谱测定。所建方法对肉类食品溯源和考古研究等领域富含有机质样品的Sr同位素比值测定具有普适性。     

掺杂立方碘化铊单晶的溶解度测定——间接银量法电导滴定微量碘离子

掺杂立方T1I单晶是长期以来探索的新型红外光学材料。由于T1I晶体是个多形变体,在通常条件下只有黄色正交相才能稳定存在。文献所载的T1I溶解度数据,没说明是哪一种构型的测定值。我们在研制出掺杂立方T1I单晶之后,测定它在各类溶剂中的溶解度,     

On-chip fraction collection for multiple selected ssDNA fragments using isolated extraction channels

High efficiency and high-purity fraction collection is highly sought in analysis of fragments-of-interest from selective polymerase chain reaction (PCR) products generated by High Coverage Gene Expression Profiling (HiCEP) methods. Here we demonstrate a new electrophoretic chip device enabling automatic high-efficient fractionation of multiple ssDNA target fragments during a run of separation. We used thoroughly isolated extraction channels for each selected target to reduce the risk of cross-contamination between targets due to cross-talk of extraction channels. Fragments of 35, 108 and 138 b, were successfully isolated, then the recovery was PCR-amplified and assessed by capillary electrophoresis (CE) analysis. Total impurity level of the targets due to unwanted fragments of 0.7%, 2% and 6% respectively, was estimated. Difficulties in collecting multiple target factions are due to band diffusion and DNA adsorption to the walls for the fragments in the separation channel, which is generated by transferring the DNA target fraction from the extraction section to the target reservoir. Therefore, we have carefully measured band broadening and analyzed its influence on the separation resolution due to the delay.     

High-throughput characterization for organic pollutants in environmental waters using a capillary electrophoresis chip.

To evaluate organic pollution in water, we did preliminarily studies on high-throughput characterization of organic pollution in water using microchip-based capillary electrophoresis (CE) with laseer-induced fluorescence (LIF) detection. The applied voltage was investigated to control the gated valve injection and CE separation for conventional cross type microchips using a self-made personal computer (PC)-based controller as the voltage supply. We obtained high-throughput data for the reproducible separation of fluorescein isothiocyanate (FITC)-labeled river-water samples using a zwitter-ion based buffer solution to avoid adsorption of the labeled sample onto the channel of a microchip made from quartz glass. We used real samples from the Hino River that flows into Lake Biwa, from ten sampling points and obtained several reproducible peaks in different separation patterns for each sample within 2 min. We successfully demonstrated high-throughput characterization of dissolved organic carbon (DOC) in environmental water using the microchip.     

Analysis of channel-geometry effects on separation efficiency in rectangular-capillary electrochromatography columns

A three-dimensional random walk model was developed to evaluate the impact of column geometry on separation efficiency in chromatography systems driven by electroosmotic flow. Contributions of injection plug length, cross-sectional area of channels, and aspect ratio of rectangular channels were examined in these simulation studies. Sample plug length had no impact on efficiency until it exceeded roughly 0.4% of the channel length. Plate height increased rapidly with increasing k' as expected, almost doubling in going from k'=0.25 to 0.35. Channel geometry also had a major effect on efficiency. Plate height increased sharply in rectangular channel columns until the channel aspect ratio reached 4-8. But the effect of channel depth was even more dramatic. Minimum plate height (Hmin) was roughly half that of the channel depth in ideal cases. Hmin in a 10x2 microm channel was at 1.6 mm s(-1). Rectangular channels comparable to those obtained by microfabrication are equivalent to packed column capillary electrochromatography columns in all cases.     

Peak dispersion and contributions to plate height in nonaqueous capillary electrophoresis at high electric field strengths: ethanol as background electrolyte solvent

Nonaqueous capillary electrophoretic separations were performed under high electric field strengths (up to 2000 Vcm(-1)) in ethanolic background electrolyte solution and the contributions of different band broadening effects to plate height were evaluated. Under optimum conditions, increasing the field strength will provide faster separations and increased separation efficiency. Decrease in the separation efficiency at high field strengths was, however, observed in a previous study and now in the present paper an attempt is made to quantify various band broadening effects by applying a plate height model, which included the contributions of the injection plug length, diffusion, electromigration dispersion, Joule heating, analyte adsorption to the capillary wall, and detector slit aperture length. Of special interest were the contributions of Joule heating and analyte adsorption to the capillary wall. Poly(glycidylmethacrylate-co-N-vinylpyrrolidone)-coated fused-silica capillaries were used with internal diameters (ID) ranging from 30 to 75 microm. The separation efficiencies obtained experimentally were compared with the theoretically calculated efficiencies and fairly good agreement was observed for the 30 microm ID capillary. Relatively large deviation from the predictions of the model was found for the other capillary diameters especially at higher field strengths. The possible reasons for the deviation were discussed.     

Capillary-assembled microchip as an on-line deproteinization device for capillary electrophoresis

A capillary-assembled microchip (CAs-CHIP), prepared by simply embedding square capillaries in a lattice polydimethylsiloxane (PDMS) channel plate with the same channel dimensions as the outer dimensions of the square capillaries, has been used as a diffusion-based pretreatment attachment in capillary electrophoresis (CE). Because the CAs-CHIPs employ square-section channels, diffusion-based separation of small molecules from sample solutions containing proteins is possible by using the multilayer flow formed in the square section channel. When a solution containing high-molecular-weight and low-molecular-weight species makes contact with a buffer solution, the low-molecular-weight species, which have larger diffusion coefficients than the high-molecular-weight species, can be collected in a buffer-solution phase. The collected solution containing the low-molecular-weight species is introduced into the separation capillary to be analyzed by CE. This type of system can be used for CE analysis in which pretreatment is required to remove proteins. In this work a fluorescently labeled protein and rhodamine-based molecules were chosen as model species and a feasibility study was performed.      

Divergent flow isoelectric focusing

Continuous-flow isoelectric focusing (IEF) has the potential to be an important method in proteome analysis. The current devices do not fully use the advantages of IEF, because they do not utilize all its important features including changes in background conductivity during the focusing. A novel continuous-flow IEF method has been developed based on planar divergent flow and control of local electric field by conductivity of electrode electrolytes. A hydrophilized polypropylene nonwoven fabric was used for creation of flow and electric manifold, making the assembled device cheap, flexible and easy to set up and operate. By using the colored low-molecular-weight pI markers we demonstrated much higher speed of focusing in the new designed channel in comparison with a channel based on currently used rectangular geometry. The developed divergent-flow IEF combines the speed of micro flow channels with the separation efficiency and sample load capacity of preparative devices.     

Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species

The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices.     

Sample preconcentration by field amplification stacking for microchip-based capillary electrophoresis

A microchip structure for field amplification stacking (FAS) was developed, which allowed the formation of comparatively long, volumetrically defined sample plugs with a minimal electrophoretic bias. Up to 20-fold signal gains were achieved by injection and separation of 400 microm long plugs in a 7.5 cm long channel. We studied fluidic effects arising when solutions with mismatched ionic strengths are electrokinetically handled on microchips. In particular, the generation of pressure-driven Poiseuille flow effects in the capillary system due to different electroosmotic flow velocities in adjacent solution zones could clearly be observed by video imaging. The formation of a sample plug, stacking of the analyte and subsequent release into the separation column showed that careful control of electric fields in the side channels of the injection element is essential. To further improve the signal gain, a new chip layout was developed for full-column stacking with subsequent sample matrix removal by polarity switching. The design features a coupled-column structure with separate stacking and capillary electrophoresis (CE) channels, showing signal enhancements of up to 65-fold for a 69 mm long stacking channel.     

Bundled capillary electrophoresis using microstructured fibres

Joule heating, arising from the electric current passing through the capillary, causes many undesired effects in CE that ultimately result in band broadening. The use of narrow‐bore capillaries helps to solve this problem as smaller cross‐sectional area results in decreased Joule heating and the rate of heat dissipation is increased by the larger surface‐to‐volume ratio. Issues arising from such small capillaries, such as poor detection sensitivity, low loading capacity and high flow‐induced backpressure (complicating capillary loading) can be avoided by using a bundle of small capillaries operating simultaneously that share buffer reservoirs. Microstructured fibres, originally designed as waveguides in the telecommunication industry, are essentially a bundle of parallel ～5 μm id channels that extend the length of a fibre having otherwise similar dimensions to conventional CE capillaries. This work presents the use of microstructured fibres for CZE, taking advantage of their relatively high surface‐to‐volume ratio and the small individual size of each channel to effect highly efficient separations, particularly for dye‐labelled peptides.