罗丹明B的电致化学发光行为研究

研究发现罗丹明B在碱性溶液中铂电极上有较强的电致化学发光行为.通过对不同NaOH浓度,以及对不同支持电解质的考察,确定最佳电致化学发光条件.在最优条件下,在1.2×10-7~1.1×10-6mol/L浓度范围内,罗丹明B的电致化学发光强度与其浓度成线性关系,最低检测限为9.0×10-8mol/L(S/N=3).将罗丹明B同一些生物活性物质相配合,然后通过罗丹明B的ECL技术对生物活性物质进行检测.     

介孔L材料CMK-3对甲基紫的吸附性能

合成了高度有序的具有二维六方(P6mm)结构的介孔碳材料CMK-3;利用X射线衍射分析了CMK-3的晶体结构,利用氮气吸脱附(BET)试验测定了孔体积;测定了CMK-3对水溶液中甲基紫的吸附行为,考察了不同pH、温度及浓度下水溶液中甲基紫的静态吸附行为,并分析了酸性、中性、碱性条件下吸附剂对甲基紫和罗丹明B混合溶液的竞...     

内部萃取电喷雾电离质谱对二氧化钛纳米线阵列光催化降解罗丹明B反应机理的研究

利用水热合成法在掺杂F的SnO₂导电玻璃(FTO)基底上制备TiO₂纳米线阵列结构, 与内部萃取电喷雾电离质谱(iEESI-MS)联用, 实现了罗丹明B降解中间产物的检测, 并推测了反应机理. 考察了离子源电压、 离子传输管温度和洗脱剂组成对罗丹明B及其降解产物信号强度的影响. 结果表明, 在光催化反应时间为2 h, 反应溶液体积为15 μL, 离子源电压为3 kV, 离子传输管温度为300 ℃, 洗脱剂为0.5%乙酸-甲醇(体积比)混合溶液条件下, 可以获得最佳的罗丹明B及其中间产物信号. 在优化的条件下, 从罗丹明B反应溶液中共检测出8种中间产物, 基于此推测了罗丹明B的降解机理. 该方法对罗丹明B定量分析的检出限(S/N≥3)为0.1 μg/L, 相对标准偏差(RSD, n=6)为2.1%~7.3%, 具有检测限低、 灵敏度高、 样品耗量少、 分析速度快及操作简便等特点. 此外, 该方法还可用于其它光催化反应中间产物的检测, 拓宽了质谱分析法在环境领域中的应用范围, 为今后环境污染物降解机理的探究提供了新思路.     

铁(Ⅲ)-硫氰酸根-乙基罗丹明B缔合体系微乳液分光光度法测定铝合金中铁

提出了微乳液分光光度法测定铝合金中铁含量的方法。在比色管中,先后加入0.5 mol·L^-1硫酸溶液3.00 mL、铁（Ⅲ）标准溶液,2 mol·L^-1硫氰酸钾溶液3.00 mL、5 g·L^-1阿拉伯树胶溶液0.8 mL、微乳液0.70 mL及1×10^-3 mol·L^-1乙基罗丹明B溶液3.00 mL使反应生成铁与硫氰酸盐的络阴离子和乙基罗丹明B的缔合物。微乳液和阿拉伯树胶对此显色体系具有显著的增溶作用。铁（Ⅲ）的质量浓度在0.026～0.36 mg·L^-1范围内与其吸光度呈线性关系。反应体系的吸收峰位于波长620 nm处,在此波长条件下测定其表观摩尔吸光率为1.08×10⁵ L·mol^-1·cm^-1。方法用于测定铝合金试样中铁量,测定值的相对标准偏差（n=5）小于2%。     

纳米固相微萃取应用于干红辣椒、水果饮料及红酒中罗丹明B的定量分析

制备了一种新型的聚苯乙烯纳米纤维, 将其作为固相萃取吸附剂装填制成固相萃取柱, 与高效液相色谱联用建立了干辣椒、 水果饮料及红酒中罗丹明B的定量分析方法. 高效液相色谱以3 g/L磷酸缓冲液-甲醇混合溶液(体积比3∶7, pH=7.0)为流动相. 通过对提取条件的优化, 得到该方法对干辣椒中罗丹明B的检出限为0.1 ng/g, 最低定量限为0.6 ng/g; 对水果饮料和红酒中罗丹明B的检出限均为0.2 ng/mL, 最低定量限均为0.5 ng/mL. 此方法对干辣椒中罗丹明B的提取回收率为98.2%~110.3%; 对水果饮料中罗丹明B的提取回收率为94.6%~102.2%; 对红酒中罗丹明B的提取回收率为90.4%~104.6%. 该方法的线性范围为1~100 ng/mL(ng/g), 相对标准偏差为2.3%~9.0%. 该方法灵敏度高、 选择性好, 可用于干辣椒、 水果饮料及红酒中罗丹明B的定量分析.     

三种形貌BiVO_4微纳材料的制备及其光催化性能研究

本文以Bi(NO_3)_3·5H_2O和NH4VO3为原料,以甲酰胺和尿素为不同碱源来调节pH值,采用水热法合成出三种不同形貌和晶型的BiVO_4微纳材料。实验结果显示,不加碱源时(反应后pH约为2.35)得到四方锆石结构和单斜晶系白钨矿结构混合相的类球状BiVO_4;加入甲酰胺时(反应后pH约为6.54)得到羽毛状单斜晶系白钨矿BiVO_4;而加入尿素时(反应后pH达到8.91)所得产物则为草垛状锆石结构和白钨矿结构的混合相BiVO_4。当以罗丹明B为降解对象,上述三种BiVO_4样品光催化性能的考察结果表明,在紫外光照射下,类球状的混合相BiVO_4微纳材料表现出最好的光催化性能,在120 min内使罗丹明B水溶液的脱色率达到98.28%。在可见光照射下,羽毛状白钨矿BiVO_4微纳材料则对罗丹明B表现出最好的降解效果,6 h内脱色率达到97.23%。     

纳米固相微萃取应用于干红辣椒、水果饮料及红酒中罗丹明B的定量分析（英文）

制备了一种新型的聚苯乙烯纳米纤维,将其作为固相萃取吸附剂装填制成固相萃取柱,与高效液相色谱联用建立了干辣椒、水果饮料及红酒中罗丹明B的定量分析方法.高效液相色谱以3 g/L磷酸缓冲液-甲醇混合溶液(体积比3∶7,pH=7.0)为流动相.通过对提取条件的优化,得到该方法对干辣椒中罗丹明B的检出限为0.1 ng/g,最低定量限为0.6 ng/g;对水果饮料和红酒中罗丹明B的检出限均为0.2 ng/m L,最低定量限均为0.5 ng/m L.此方法对干辣椒中罗丹明B的提取回收率为98.2%~110.3%;对水果饮料中罗丹明B的提取回收率为94.6%~102.2%;对红酒中罗丹明B的提取回收率为90.4%~104.6%.该方法的线性范围为1~100 ng/m L(ng/g),相对标准偏差为2.3%~9.0%.该方法灵敏度高、选择性好,可用于干辣椒、水果饮料及红酒中罗丹明B的定量分析.     

罗丹明B荧光猝灭法测定消毒液中过氧乙酸的含量

在总体积为50.0mL的溶液中加入0.1mol·L~(-1)硫酸溶液2.0mL,0.1mol·L~(-1)碘化钾溶液2.0mL及1.0×10-4 mol·L~(-1)罗丹明B溶液5.0mL,以荧光激发波长为365nm,在荧光最大发射波长580nm处可测得罗丹明B发出的明显荧光。当在此条件下,加入过氧乙酸能使其荧光强度迅速减弱,且其减弱程度与过氧乙酸的浓度在4.2×10-7～5.0×10-5 mol·L~(-1)内呈线性关系,并根据10次空白溶液的平行测定计算得到此方法的检出限(3s/k)为2.0×10-8 mol·L~(-1)。据此提出了罗丹明B荧光猝灭法测定消毒液中过氧乙酸的含量。分析时取样品溶液0.25mL,滴加0.01mol·L~(-1)高锰酸钾溶液至溶液呈稳定的浅粉红色,加水稀释至500.0mL,制得样品待测液。取此溶液1.0mL,加入于上述反应溶液中(在加入碘化钾溶液之后),放置15min后按上述方法操作。在3件不同来源的样品按此方法进行分析并进行加标回收试验,测得回收率在96.5%～97.5%之间,测定总量的相对标准偏差(n=6)在1.3%～2.6%之间。所测得此3个样品的过氧乙酸含量均与其标示量相符。由于过氧乙酸标准溶液的不稳定性导致所测得回收率均低于100%。     

基于银染放大和图像分析的高灵敏铅离子检测北大核心CSCD

构建了一种基于银染放大和图像分析的高灵敏铅离子检测方法。采用双硫腙溶液处理尼龙膜制备检测试纸。试纸上的双硫腙可捕获溶液中的Pb^(2+),并进一步与Na_(2)S反应生成PbS,PbS催化随后的银染反应,实现信号放大。用扫描仪扫描试纸,通过软件分析图像的灰度值,可实现Pb^(2+)的定量检测。考察了膜种类、溶液pH和银染条件的影响,在优化的检测条件下,试纸的灰度值与Pb^(2+)浓度的对数呈良好的线性关系(相关系数R^(2)=0.994),检出限为13.2 nmol/L(0.0027 mg/L),灵敏度可满足饮用水质检测要求。利用本法对Pb^(2+)加标的自来水样品进行分析,1μmol/L和10μmol/L Pb^(2+)的回收率分别为92.2%和96.0%,相对标准偏差(RSD,n=3)为6.1%和5.3%。该方法可用于实际水样中Pb^(2+)的分析。     

荧光光谱的罗丹明B校正原理

一般荧光光谱仪推荐的校正方法是罗丹明B法,但仪器说明书对该方法的原理没有介绍。本文通过研究不同浓度罗丹明B溶液的激发光谱、发射光谱和吸收光谱再结合理论分析阐明了罗丹明B浓溶液可作为量子计数器的原因及其校正光谱的原理。     

Development of a passive micromixer based on repeated fluid twisting and flattening,and its application to DNA purification

We have developed a three-dimensional passive micromixer based on new mixing principles, fluid twisting and flattening. This micromixer is constructed by repeating two microchannel segments, a “main channel” and a “flattened channel”, which are very different in size and are arranged perpendicularly. At the intersection of these segments the fluid inside the micromixer is twisted and then, in the flattened channel, the diffusion length is greatly reduced, achieving high mixing efficiency. Several types of micromixer were fabricated and the effect of microchannel geometry on mixing performance was evaluated. We also integrated this micromixer with a miniaturized DNA purification device, in which the concentration of the buffer solution could be rapidly changed, to perform DNA purification based on solid-phase extraction.     

Facile fabrication of a rigid and chemically resistant micromixer system from photocurable inorganic polymer by static liquid photolithography (SLP)

Highly effective mixing in microchannels is important for most chemical reactions conducted in microfluidic chips. To obtain a rigid and chemically resistant micromixer system at low cost, we fabricated a Y-shaped microchannel with built-in mixer structures by static liquid photolithography (SLP) from methacrylated polyvinylsilazane (MPVSZ) as an inorganic polymer photoresist which was then converted to a silicate phase by hydrolysis in vaporized ammonia atmosphere at 80 °C. The microchannel incorporating herringbone mixer structures was bonded with a matching polydimethylsiloxane (PDMS) open channel which was pre-coated by perhydropolysilazane (PHPS)-based mixture, and finally treated by additional hydrolysis at room temperature to convert the PHPS layer to a silica phase. Finally, the chemical resistance of the microfluidic system with embedded micromixer was confirmed with various solvents, and the excellent mixing performance in a short mixing length of 2.3 cm was demonstrated by injecting two different colored fluids into the microchannel.     

Design and Fabrication of a Three Dimensional Spiral Micromixer

In this work, we present a three dimensional micromixer which consists of two layers of spiral channels overlapped together in the vertical direction. This micromixer is designed by using a smooth channel twisted into double‐layer spiral geometry with simple topological structure. Based on the principle of Dean effects, this kind of structure is beneficial to produce, enhance and sustain the Dean vortices, which can perturb the laminar fluid effectively. In order to improve the mixing performance, the detailed parameters have been optimized by using the computational fluid dynamics software. The results indicate that the erect channel which is connected with the two layers of spiral channels plays a critical role for well mixing. Meanwhile, the effect of mixing has been identified in a fabricated glass‐micromixer. The mixing ef?ciency of 90% has been achieved by optimizing the flow rate and the structure of the erect channel. Thus, this micromixer has manifested high mixing efficiency and presents good practicability in the versatile microfluidic systems.     

A novel 3D Tesla valve micromixer for efficient mixing and chitosan nanoparticle production

Current three-dimensional micromixers for continuous flow reactions and nanoparticle synthesis are complex in structure and difficult to fabricate. This paper investigates the design, fabrication, and characterization of a novel micromixer that uses a simple spatial Tesla valve design to achieve efficient mixing of multiple solutions. The flow characteristics and mixing efficiencies of our Tesla valve micromixer are investigated using a combination of numerical simulations and experiments. The results show that in a wide range of flow rates, viscoelastic solutions with different concentrations can be well mixed in our micromixer. Finally, experiments on the synthesis of chitosan nanoparticles are conducted to verify the practicability of our micromixer. Compared with nanoparticles prepared by conventional magnetic stirring, the size of nanoparticles prepared by micromixing is smaller and the distribution is more uniform. Therefore, our Tesla valve micromixer has significant advantages and implications for mixing chemical and biological reactions.     

Mixing in microchannels based on hydrodynamic focusing and time-interleaved segmentation: modelling and experiment

This paper theoretically and experimentally investigates a micromixer based on combined hydrodynamic focusing and time-interleaved segmentation. Both hydrodynamic focusing and time-interleaved segmentation are used in the present study to reduce mixing path, to shorten mixing time, and to enhance mixing quality. While hydrodynamic focusing reduces the transversal mixing path, time-interleaved sequential segmentation shortens the axial mixing path. With the same viscosity in the different streams, the focused width can be adjusted by the flow rate ratio. The axial mixing path or the segment length can be controlled by the switching frequency and the mean velocity of the flow. Mixing ratio can be controlled by both flow rate ratio and pulse width modulation of the switching signal. This paper first presents a time-dependent two-dimensional analytical model for the mixing concept. The model considers an arbitrary mixing ratio between solute and solvent as well as the axial Taylor-Aris dispersion. A micromixer was designed and fabricated based on lamination of four polymer layers. The layers were machined using a CO2 laser. Time-interleaved segmentation was realized by two piezoelectric valves. The sheath streams for hydrodynamic focusing are introduced through the other two inlets. A special measurement set-up was designed with synchronization of the mixer's switching signal and the camera's trigger signal. The set-up allows a relatively slow and low-resolution CCD camera to freeze and to capture a large transient concentration field. The concentration profile along the mixing channel agrees qualitatively well with the analytical model. The analytical model and the device promise to be suitable tools for studying Taylor-Aris dispersion near the entrance of a flat microchannel.     

Design of passive mixers utilizing microfluidic self-circulation in the mixing chamber

This paper proposes the design of a passive micromixer that utilizes the self-circulation of the fluid in the mixing chamber for applications in the Micro Total Analysis Systems (microTAS). The micromixer with a total volume of about 20 microL and consisting of an inlet port, a circular mixing chamber and an outlet port was designed. The device was actuated by a pneumatic pump to induce self-circulation of the fluid. The self-circulation phenomenon in the micromixer was predicted by the computational simulation of the microfluidic dynamics. Flow visualization with fluorescence tracer was used to verify the numerical simulations and indicated that the simulated and the experimental results were in good agreement. Besides, an index for quantifying the mixing performance was employed to compare different situations and to demonstrate the advantages of the self-circulation mixer. The mixing efficiencies in the mixer under different Reynolds numbers (Re) were evaluated numerically. The numerical results revealed that the mixing efficiency of the mixer with self-circulation was 1.7 to 2 times higher than that of the straight channel without a mixing chamber at Re= 150. When Re was as low as 50, the mixing efficiency of the mixer with self-circulation in the mixing chamber was improved approximately 30% higher than that in the straight channel. The results indicated that the self-circulation in the mixer could enhance the mixing even at low Re. The features of simple mixing method and fabrication process make this micromixer ideally suitable for microTAS applications.     

A pneumatic micromixer facilitating fluid mixing at a wide range flow rate for the preparation of quantum dots

A novel fluid micromixer based on pneumatic perturbation and passive structures was developed. This micromixer facilitates integration and is applicable to fluid mixing over a wide range of flow rates. The microfluidic mixing device consists of an S-shaped structure with two mixing chambers and two barriers, and two pneumatic chambers designed over the S-shaped channel. The performance of the micromixer for fluids with wide variation of flow rates was significantly improved owing to the integration of the pneumatic mixing components with the passive mixing structures. The mixing mechanism of the passive mixing structures was explored by numerical simulation, and the influencing factors on the mixing efficiency were investigated. The results showed that when using a gas pressure of 0.26 MPa and a 100 m-thick polydimethylsiloxane (PDMS) pneumatic diaphragm, the mixing of fluids with flow rates ranging from 1 to 650 L/min was achieved with a pumping frequency of 50 Hz. Fast synthesis of CdS quantum dots was realized using this device. Smaller particles were obtained, and the size distribution was greatly improved compared with those obtained using conventional methods.     

An easily integrative and efficient micromixer and its application to the spectroscopic detection of glucose-catalyst reactions

The focus of this paper is on the fabrication of a PDMS-based passive efficient micromixer to be easily integrated into the other on-chip microfluidic system. The mixing is achieved by "strong stretching and folding," which employs a three-dimensional microchannel structure. By the simultaneously vertical and transversal dispersion of fluids, strong advection is developed. Owing to this powerful mixing performance (more than 70% of the mixing is accomplished within 2.3 mm over a wide range of Reynold number (Re)), the smaller integrative mixer can be realized. The feasibility and the potential usefulness of an integrative micromixer were evaluated by incorporating two mixers into the microchannel for the spectroscopic detection of a glucose-catalyst reaction. The results demonstrate a promising performance for diverse applications in the assay or synthesis of biological or chemical materials.     

Passive micromixer for luminol-peroxide chemiluminescence detection

This paper reports a microchip with an integrated passive micromixer based on chaotic advection. The micromixer with staggered herringbone structures was used for luminol-peroxide chemiluminescence detection. The micromixer was examined to assess its suitability for chemiluminescence reaction. The relationship between the flow rate and the location of maximum chemiluminescence intensity was investigated. The light intensity was detected using an optical fiber attached along the mixing channel and a photon detector. A linear correlation between chemiluminescence intensity and the concentration of cobalt(ii) ions or hydrogen peroxide was observed. This microchip has a potential application in environmental monitoring for industries involved in heavy metals and in medical diagnostics.     

A model for laminar diffusion-based complex electrokinetic passive micromixers

This paper presents a model for the efficient and accurate simulations of laminar diffusion-based complex electrokinetic passive micromixers by representing them as a system of mixing elements of relatively simple geometry. Parameterized and analytical models for such elements are obtained, which hold for general sample concentration profiles and arbitrary flow ratios at the element inlet. A lumped-parameter and system-level model is constructed for a complex micromixer, in which the constituent mixing elements are represented by element models, in such a way that an appropriate set of parameters are continuous at the interface between each pair of adjacent elements. The system-level model, which simultaneously computes electric circuitry and sample concentration distributions in the entire micromixer, agrees with numerical and experimental results, and offers orders-of-magnitude improvements in computational efficiency over full numerical simulations. The efficiency and usefulness of the model is demonstrated by exploring a number of laminar diffusion based mixers and mixing networks that occur in practice.