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1.
新型单光子电离和光电子电离复合电离源的研究及应用   总被引:2,自引:0,他引:2  
复合电离源在单光子电离模式下可以产生分子离子信号,易于确定分子量;在光电子电离模式下,70eV电子能量可以产生含有物质结构信息的碎片峰,实现物质的结构鉴定。两种电离模式可以实现毫秒级迅速切换。本研究通过提高光程降低了单光子电离模式下的检出限。在单光子电离模式下,对苯的检出限为50"g/m3(累加时间为4s);光电子电离模式下,对SO2的检出限为20"L/m3(累加时间4s)。利用复合电离源的单光子电离模式分析了烷烃催化脱氢产物,成功实现了碳链长度为8~12的烷烃,烯烃和二烯烃的在线分析和监测。此外,还利用低能电子的光电子电离模式分析了高压变压器保护气,检测了主要杂质成分,为高压变压器中故障的快速诊断提供依据。  相似文献
2.
质子转移反应质谱在线检测痕量挥发性有机物   总被引:1,自引:0,他引:1  
质子转移反应质谱是近年来兴起的一种痕量挥发性有机物在线检测技术,它可以在秒量级的时间内获得ppt量级的探测灵敏度,已经广泛的应用在环境污染监测、医学诊断、食品成分和质量检验等领域。本文介绍了它的工作原理和装置结构,给出了一些痕量挥发性有机物检测的例子,以及作者实验室使用该技术检测挥发性有机物的初步研究结果,并对该在线检测技术的发展方向进行了展望。  相似文献
3.
Increasingly stringent demands on the production of biopharmaceuticals demand monitoring of process parameters that impact on their quality. We developed an automated platform for on-line, near real-time monitoring of suspension cultures by integrating microfluidic components for cell counting and filtration with a high-resolution separation technique. This enabled the correlation of the growth of a human lymphocyte cell line with changes in the essential metabolic markers, glucose, glutamine, leucine/isoleucine and lactate, determined by Sequential Injection-Capillary Electrophoresis (SI-CE). Using 8.1 mL of media (41 μL per run), the metabolic status and cell density were recorded every 30 min over 4 days. The presented platform is flexible, simple and automated and allows for fast, robust and sensitive analysis with low sample consumption and high sample throughput. It is compatible with up- and out-scaling, and as such provides a promising new solution to meet the future demands in process monitoring in the biopharmaceutical industry.  相似文献
4.
Abstract  An e-nose comprised of six sensing channels each coated with a molecularly imprinted polymer (MIP) selectively interacting with alpha-pinene, thymol, estragol, linalool, and camphor, respectively, was designed. When applying it for continuous online surveillance of terpenes emitted from basil and peppermint leaves as a criterion of freshness, it very appreciably reproduced the emanation patterns from these plants as shown by GC-MS. Chromatography yielded a variety of terpenes in a concentration range below 70 ppm. Trend lines obtained from the e-nose were corroborated by GC-MS and also appreciably fit the usual conduct of these plants as observable by the human nose. Graphical abstract     相似文献
5.
Translating controlled/living radical polymerization (CLRP) from batch to the high throughput production of polymer libraries presents several challenges in terms of both polymer synthesis and characterization. Although recently there have been significant advances in the field of low volume, high throughput CLRP, techniques able to simultaneously monitor multiple polymerizations in an “online” manner have not yet been developed. Here, we report our discovery that 5,10,15,20‐tetraphenyl‐21H,23H‐porphine zinc (ZnTPP) is a self‐reporting photocatalyst that can mediate PET‐RAFT polymerization as well as report on monomer conversion via changes in its fluorescence properties. This enables the use of a microplate reader to conduct high throughput “online” monitoring of PET‐RAFT polymerizations performed directly in 384‐well, low volume microtiter plates.  相似文献
6.
Monitoring and control of free radical copolymerization using automatic continuous online monitoring of polymerization reactions (ACOMP) with UV detection has been recently achieved. It is difficult, however, to achieve spectral separation of similar monomers with UV alone. Here, nuclear magnetic resonance (NMR) is coupled to ACOMP for the first time and terpolymerization reactions involving acrylamide (Am), sodium acrylate (Ac), and styrene sulfonate (SS) are monitored, and a first attempt at active composition control is made. The NMR resolves the concentrations of Am and Ac, while the UV resolves SS and the sum of Am and Ac. NMR analysis is performed in water, using signal suppression, to eliminate the need for deuterated solvents. From this, instantaneous fractions of each comonomer in the terpolymer are continuously known, along with weight average molecular weight and intrinsic viscosity, IV. Am and Ac have similar reactivities, whereas the reactivity ratio of SS is much larger. Hence, there is high composition drift in batch polymerization and SS is rapidly consumed, leaving a final copolymer of Am and SS to form. Maintaining constant terpolymer composition is taken as a first step toward active control.  相似文献
7.
Microfluidics can be used to handle relatively small volumes of samples and to conduct reactions in microliter‐sized volumes. Electrospray ionization can couple microfluidics with mass spectrometry (MS) to monitor chemical reactions online. However, fabricating microfluidic chips is time‐consuming. We herein propose the use of a micro‐reactor that is sustained by two capillaries and an ultrasonicator. The inlets of the capillaries were individually immersed to two different sample vials that were subjected to the ultrasonicator. The tapered outlets of the two capillaries were placed cross with an angle of ~60° close to the inlet of the mass spectrometer to fuse the eluents. On the basis of capillary action and ultrasonication, the samples from the two capillaries can be continuously directed to the capillary outlets and fuse simultaneously to generate gas phase ions for MS analysis through ultrasonication‐assisted spray ionization (UASI). Any electric contact applied on the capillaries is not required. Nevertheless, UASI spray derived from the eluents can readily occur in front of the mass spectrometer. That is, a micro‐reactor was created from the fusing of the eluent containing different reactants from these two UASI capillaries, allowing reactions to be conducted in situ. The solvent in the fused droplets was evaporated quickly, and the product ions could be immediately observed by MS because of the extreme rise in the concentration of the reactants. For proof of concept, pyrazole synthesis reaction and cortisone derivatization by Girard T reagent were selected as the model reactions. The results demonstrated the feasibility of using UASI‐based micro‐reactor for online MS analysis to detect reaction intermediates and products.  相似文献
8.
Polymer particle growth in catalytic ethylene slurry polymerizations with SiO2‐supported metallocene and post‐metallocene catalysts was monitored online using a Lasentec FBRM probe inserted into the stirred reactor. FBRM enabled the online monitoring of particle numbers and size distributions. Trend analyses provided time‐resolved information on selected variables of the particle growth processes. FBRM was combined with simultaneous ethylene mass flow measurements in order to distinguish between ideal particle growth and more complex growth processes involving particle fragmentation and aggregation. Additional use of a Lasentec PVM video microscopy probe during ethylene polymerization on a MgCl2‐supported Ziegler catalyst enabled the online visualization of PE particles, complementing the data generated by FBRM online monitoring.

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9.
We report the development of a new method for online characterization of polymers, termed Continuous Online Rapid Size‐Exclusion chromatography Monitoring of Polymerizations (CORSEMP). It consists of automatic samplings, dilutions and injections every 12 min of polymers synthesized in continuous flow. The system allows molecular weight and molecular weight distribution of polymers to be monitored ‘near real‐time’ by means of a chromatographic column. This technique is well adapted to assessment of the effects of stepwise modifications of operating conditions over the dynamics of the reactor by running high‐throughput experiments and shows itself to be a convenient tool for polymer library synthesis.

  相似文献

10.
利用自主研发的实时在线监测系统,对不同聚合温度条件下,聚甲基丙烯酸甲酯(PMMA)的本体聚合过程进行实时在线监测,建立"虚拟信号值-反应时间"实时在线监测曲线.通过曲线的变化,可以清晰观察到PMMA本体聚合过程的4个阶段,即诱导期、初期、中期和后期.根据本体聚合"转化率-反应时间"S型曲线的特点,构建"虚拟信号值-反应时间-转化率"关系曲线和聚合物转化率计算公式,并提出PMMA预聚体的预测和实时在线监测方法.方法具有操作简单、实时性强、外界因素影响小和性能稳定等优点,是一种新型的实时在线分析方法.  相似文献
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