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71.
Du Liping Ding Yuqing Prokop Aleš Tanner Robert D. 《Applied biochemistry and biotechnology》2001,91(1-9):387-404
Bubble size is a key variable for predicting the ability to separate and concentrate proteins in a foam fraction ation process.
It is used to characterize not only the bubble-specific interfacial a rea but also coalescence of bubbles in the foam phase.
This article describes the development of a photoelectric method for measuring the bubble size distribution in both bubble
and foam columns for concentrating proteins. The method uses a vacuum to withdraw a stream of gas-liquid dispersion from the
bubble or foam column through a capillary tube with a funnel-shaped inlet. The resulting sample bubble cylinders are detected,
and their lengths are calculated by using two pairs of infrared photoelectric sensors that are connected with a high-speed
data acquisition system controlled by a microcomputer. The bubble size distributions in the bubble column 12 and 1 cm below
the interface and in the foam phase 1 cm above the interface are obtained in a continuous foam fractionation process for concentrating
ovalbumin. The effects of certain operating conditions such as the feed protein concentration, superficial gas velocity, liquid
flow rate, and solution pH are investigated. The results may prove to be helpful in understanding the mechanisms controlling
the foam fractionation of proteins. 相似文献
72.
Terenina M. B. Misharina T. A. Krikunova N. I. Golovnya R. V. 《Russian Chemical Bulletin》2001,50(6):1032-1036
Capillary gas chromatography was applied to study the sorption of aliphatic ketones (C6—C11), including metamers, from aqueous solutions by corn starch cryotextures. The amount of ketones sorbed by cryotextures depends linearly on their concentrations in the initial sol. Equations describing the concentration dependence of sorption were proposed. The shape of sorption isotherms reflects the strength of sorption. The binding constants and the number of binding sites were determined for weakly sorbed ketones. The length of alkyl substituent and the position of the functional group are the crucial factors governing the sorption of ketones under conditions of excess binding sites. It was found that the degree of sorption increases with an increase in the carbon chain length from 6 to 9 carbon atoms. The presence of cooperation of binding sites for ketone sorption by cryotextures was demonstrated. The major part of ketones is sorbed irreversibly. This fact points to the formation of supramolecular complexes. Ketones with lower molecular masses are better sorbed by cryotextures than by native starch grains. 相似文献
73.
L. M. Khalilov E. A. Paramonov A. Z. Khalilova V. N. Odinokov A. A. Muldashev U. A. Baltaev U. M. Dzhemilev 《Chemistry of Natural Compounds》2001,37(4):339-342
The components of fragrance from four wormwood species of theArtemisiaL. genus were analyzed by GC-MS. The major and minor components of volatile essential oils typical of the studied plant species were determined. 相似文献
74.
75.
吸附蛋白质固定相电色谱手性分离的研究 总被引:4,自引:1,他引:4
将牛血清白蛋白 (BSA)吸附于强阴离子交换固定相 (SAX)上用于电色谱手性分离。当SAX吸附BSA后 ,电渗淌度仅仅下降 2 6 3% ,而电渗流的方向没有改变。在该系统中电渗流的方向和阴离子的电泳方向一致 ,因而克服了一般蛋白质固定相不能分离酸性对映体的缺点。 1种中性对映体安息香和 4种阴离子性对映体色氨酸、华法令、非诺洛芬、酮基布洛芬获得了成功分离。当流动相含体积分数为 7%的乙腈时 ,死时间和D 色氨酸、L 色氨酸的迁移时间的相对标准偏差分别为 0 90 % ,0 87%和 0 96 % (n =2 1) ,说明该体系有很好的重现性。 相似文献
76.
毛细管电泳法测定桑叶中的黄酮类成分──芦丁和槲皮素 总被引:17,自引:1,他引:17
采用高效毛细管电泳法分离测定了新疆不同地区、不同采集期、不同品种的桑叶中的黄酮类成分芦丁、槲皮素的含量。以含有体积分数为 15 %甲醇的 10mmol/L的磷酸二氢钠 2 0mmol/L的硼砂溶液 (pH 8 6 2 )为电泳缓冲液 ,采用压力进样方式 ,在 2 5℃ ,2 0kV恒压下进行电泳分离 ,并在 2 45nm波长处检测。结果表明 ,桑叶中的两种目标组分在 12min内完全分离 ,且有良好的线性关系 ;芦丁和槲皮素的加样回收率分别为 95 6 4%和99 36 % ,其RSD分别为 2 2 5 %和 1 79% (n =6 )。方法简单、准确、快速。 相似文献
77.
Separation of chiral compounds using magnetic molecularly imprinted polymer nanoparticles as stationary phase by microchip capillary electrochromatography 下载免费PDF全文
《Electrophoresis》2018,39(2):356-362
In this work, a simple and rapid approach was developed for separation and detection of chiral compounds based on a magnetic molecularly imprinted polymer modified poly(dimethylsiloxane) (PDMS) microchip coupled with electrochemical detection. Molecularly imprinted polymers were prepared employing Fe3O4 nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, Fe3O4@polynorepinephrine NPs (MIP–Fe3O4@PNE NPs) showed specific molecular recognition selectivity and high affinity towards the template molecule, which were then used as stationary phase of microchip capillary electrochromatography for chiral compounds separation. Mandelic acid and histidine enantiomers were used as model compounds to test the chiral stationary phase. By using R‐mandelic acid as the template molecule, mandelic acid enantiomer was effectively separated and detected on the MIP‐Fe3O4@PNE NPs modified PDMS microchip. Moreover, the successful separation of histidine enantiomers on the MIP–Fe3O4@PNE NPs modified microchip using L‐histidine as template molecule was also achieved. 相似文献
78.
建立了高效毛细管电泳测定游泳池水中新型尿液指示物乙酰磺胺酸钾含量的新方法。采用内壁无涂层熔融石英毛细管(60.2 cm×75μm,有效长度50 cm)进行分离,缓冲液为10 mmol/L硼砂溶液(pH 9.3),分离电压为24 k V,进样时间为20 s,检测波长为226 nm。取游泳池水样过滤,经固相萃取小柱浓缩富集后直接进样分析。结果显示:在优化条件下,乙酰磺胺酸钾在0.2~100.0 mg/L质量浓度范围内线性良好(r=0.999 8),检出限为50.0μg/L,迁移时间和峰高的相对标准偏差(RSD)分别为0.73%和1.8%,加标回收率为96.0%~103.6%。该方法简单快速、准确可靠,适用于游泳池水中乙酰磺胺酸钾的检测。 相似文献
79.
《Journal of separation science》2018,41(14):2886-2894
Because of its high conductivity when acid doped, polyaniline is known as a synthetic metal and is used in a wide range of applications, such as supercapacitors, biosensors, electrochromic devices, or solar and fuel cells. Emeraldine is the partly oxidized, stable form of polyaniline, consisting of alternating diaminobenzenoid and iminoquinoid segments. When acidified, the nitrogen atoms of emeraldine become protonated. Due to electrostatic repulsion between positive charges, the polarity and morphology of emeraldine chains presumably change; however, the protonation effects on emeraldine have not yet been clarified. Thus, we investigated these changes by reversed‐phase capillary liquid chromatography using a linear solvation energy relationship approach to assess differences in dominant retention interactions under a significantly varied mobile phase pH. We observed that hydrophobicity dominates the intermolecular interactions under both acidic and alkaline eluent conditions, albeit to different extents. Therefore, by tuning the mobile phase pH, we can even modulate the retention of neutral hydrophobic solutes, such as aromatic hydrocarbons, because the pH‐dependent charge and structure of polymer chains of the emeraldine‐coated silica stationary phase show a mixed‐mode separation mechanism. 相似文献
80.
《Journal of separation science》2018,41(14):2969-2975
Ammonium and diphenhydramine are active ingredients commonly found in the same pharmaceutical preparations. We report, for the first time, a sub‐minute method for the simultaneous determination of ammonium and diphenhydramine. The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection. Both analytes can be quantified in a single run (∼80 injections/h) using 30 mmol/L 2‐(N‐morpholino)ethanesulfonic acid and 15 mmol/L lithium hydroxide (pH 6.0) as background electrolyte. The separation by capillary electrophoresis was achieved on a fused‐silica capillary (50 cm total length, 10 cm effective length, and 50 μm inside diameter). The limits of detection were 0.04 and 0.02 mmol/L for ammonium and diphenhydramine, respectively. The proposed method also provided adequate recovery values for spiked samples (100–106 and 97–104% for ammonium and diphenhydramine, respectively). The results obtained with the new capillary electrophoresis method were compared with those of the high‐performance liquid chromatography method for diphenhydramine and the Kjeldahl method for ammonium and no statistically significant differences were found (95% confidence level). 相似文献