Electrochemical determination of hesperidin using mesoporous SiO2 modified electrode

A simple micro-capillary electrophoresis system to be used as disposable device was developed. A short commercial capillary was used as the separation channel, hydrostatic pressure generated by the sample employed for injection, and a voltage of 200 V used for separation in a 6 cm long capillary assisted by hydrostatic pressure of the carrier. The device was used for the separation of dopamine and catechol. Good reproducibility and efficiency was obtained. Because the instrumentation and operation conditions were simplified, and a replaceable modular separation channel was used, the proposed micro-capillary electrophoresis system is potentially useful in disposable devices.     

Metabolism of cheese whey lactose by kluyveromyces fragilis for energy and growth under batch condition

The fermentation of lactose byKluyveromyces fragilis is an exothermic reaction in which heat is released, resulting in a rise in reactor temperature. A heat balance was performed on a 5-L batch reactor used for single cell protein (SCP) production to determine the portions of cheese whey lactose used for energy and growth. On the average, about 88% of lactose was used for growth, and 12% was used for energy. The lactose consumed during the lag and stationary phases was used mostly for cell endogenous growth and respiration, whereas that consumed during the exponential growth phase was used for cell multiplication and energy. The heat released varied from 6.5 to 8.9 kJ/g cell. Because of the proper design of the fermenter, the temperature of the medium did not rise above 33°C; thus, no cooling system was needed.     

Electrochemical Detection of Artemisinin Using Cobalt Sulphide/Reduced Graphene Oxide Nanocomposite

Solvothermally synthesized cobalt sulphide/reduced graphene oxide (CoS/rGO) was used to fabricate an electrochemical sensor for detection of artemisinin. Microscopic techniques were used to characterize CoS/rGO nanocomposite. The electrochemical sensor was fabricated by modifying the surface of glassy carbon electrode with CoS/rGO nanocomposite. [Fe(CN)6]^3−/4− was used as a mediator to aid oxidation of artemisinin. Differential pulse voltammetric technique was used for the detection of artemisinin. A linear range of 30–100 μM was used. Experimentally, a detection limit of 0.5 μM was obtained. Therefore, the developed sensor can be used for quality control of artemisinin.     

Hazard evaluation for oxidation of cyclic ethers

Ethers are widely used as a solvent for synthesis reactions, however, they are known as hazardous chemicals as they have low flash points and form peroxides under oxidative conditions. In this study, the oxidative reactivity of cyclic ethers was evaluated by thermal analysis. The accelerated test was performed in a pressure vessel under a high oxygen pressure (2 MPa), and DSC was used to detect the products of the reaction. Tetrahydrofuran (THF) and 1,3-dioxolane were used as a sample. The result of the DSC measurement of THF without any antioxidant showed that the DSC curve depended on the exposure time. It was found that this method can be used for the oxidation evaluation. The DSC measurement was also used for the detection of ether peroxides, and this method was faster and simpler than the potassium iodine titration.     

超高效液相色谱-串联质谱法测定食用植物油中胆固醇含量

提出了食用植物油中胆固醇的超高效液相色谱-串联质谱测定方法。食用植物油经皂化后用石油醚-乙醚(1+1)溶液提取,以Waters ACQUITY UPLC BEH C18色谱柱(50mm×2.1mm,5μm)为分离柱,以甲酸-甲醇(0.1+99.9)溶液为流动相,以2,2,3,4,4,6-d6胆固醇为内标,采用大气压化学电离源在多反应监测负离子模式下进行测定,胆固醇和内标的定量离子对分别为m/z369.2/146.9,369.2/160.9和375.2/166.5。胆固醇在0.1～5mg·L-1范围内呈线性,测定下限(10S/N)为0.02ng。在3个浓度水平上对方法做回收试验,测得回收率在102%～110%之间。     

New serotonin 5-HT(6) ligands from common feature pharmacophore hypotheses

Serotonin 5-HT6 receptor antagonists are thought to play an important role in the treatment of psychiatry, Alzheimer's disease, and probably obesity. To find novel and potent 5-HT6 antagonists and to provide a new idea for drug design, we used a ligand-based pharmacophore to perform the virtual screening of a commercially available database. A three-dimensional common feature pharmacophore model was developed by using the HipHop program provided in Catalyst software and was used as a query for screening the database. A recursive partitioning (RP) model which can separate active and inactive compounds was used as a filtering system. Finally a sequential virtual screening procedure (SQSP) was conducted, wherein both the common feature pharmacophore and the RP model were used in succession to improve the results. Some of the hits were selected based on druglikeness, ADME properties, structural diversity, and synthetic accessibility for real biological evaluation. The best hit compound showed a significant IC50 value of 9.6 nM and can be used as a lead for further drug development.     

Polydopamine-modified MWCNTs-glassy Carbon Electrode,a Selective Electrochemical Morphine Sensor

An electrochemical sensor based on a glassy carbon electrode was prepared using f-MWCNTs and polydopamine. Several techniques were used to investigate the surface features. Voltammetric techniques were used to evaluate the electrocatalyst efficiency, and it was used for morphine determination using differential pulse voltammetry. Different parameters affecting the method‘s sensitivity and selectivity were optimized. The linear dynamic range was 0.075–75.0 μM with a detection limit of 0.06 μM morphine. Also, the method‘s selectivity was tested, which was proved to be satisfactory. Finally, the sensor was successfully used for morphine determination in human plasma and urine samples with acceptable results.     

气相色谱-质谱法测定纺织品中N-乙基全氟辛烷磺酰胺

提出了用气相色谱-质谱法测定纺织品中N-乙基全氟辛烷磺酰胺的方法。试样经甲醇超声提取后,在旋转蒸发仪中浓缩至5 mL,通过DB-5MS色谱柱分离,采用选择离子监测模式检测,定性离子为m/z69,108,131,169,448,定量离子为m/z108。N-乙基全氟辛烷磺酰胺的质量浓度在0.2~20.0 mg.L-1范围内与峰面积呈线性关系,检出限(3S/N)为0.69μg.L-1。用标准加入法做回收试验,测定平均回收率为97%。     

A computational model for selectivity evaluation of 2-(3,4-dimethoxyphenyl)ethylamine (homoveratrylamine) imprinted polymers towards biogenic compounds

A computational model was proposed to evaluate the affinity and selectivity of 2-(3,4-dimethoxyphenyl)ethylamine (homoveratrylamine) imprinted polymers. Four functional monomers: methacrylic acid, 1-vinylimidazole, 4-vinylpyridine, and allylamine were taken into account. Two dielectric constants were used for solvent simulations: a value of ?=2.38r(ij) for toluene was used in the analysis of prepolymerization complexes, and a value of ?=36r(ij) for methanol-water was used in the investigations of adsorption. Theoretical analysis predicted the highest affinity for the polymer synthesized from methacrylic acid. Experimental results confirmed the finding. The prepolymerization complex formed by homoveratrylamine and four methacrylic acid molecules was used to design the polymer cavity. The selectivity of the polymer was analyzed as a simulation of adsorption of six compounds in the cavity by docking procedure. Selected compounds are structurally related to the template or can be present in biological samples. The designed polymer has high selectivity towards homoveratrylamine. The proposed computational procedure could be used for successful evaluation of the imprinted polymers.     

Development of a tetramethylrhodamine-labeled probe for a capillary electrophoresis-based competitive immunoassay of staphylococcal enterotoxin B

Staphylococcal enterotoxin B (SEB) was labeled with tetramethylrhodamine isothiocyanate (TRITC) and used as a probe for a competitive immunoassay. Labeling conditions such as solution pH and time were varied to observe the effect on the fluorescent product. It was found that solution pH of the labeling reaction had little effect on the fluorescence signal of the resulting products. However, labeling at pH 7.0 produced a probe that had a higher affinity for the antibody used in this study than the probes produced at pH 8.0 and 9.0. The fluorescent probes were used to perform a competitive assay for SEB in model skim milk samples. Detection limit was approximately 300 fg of SEB. Quantitation was achieved by curve fitting of fluorescent signals for bound/free probe versus log[SEB] with logarithmic functions. Accuracy in the model skim milk samples was acceptable for 3 and 5 nM SEB, but decreased considerably for a concentration of less than 1 nM SEB. The error was attributed to deviation in linearity in the standard curve at lower concentrations. Reproducibility for the analysis of both standard solutions used for the calibration curves and the model skim milk samples was excellent, with standard deviations of approximately 10% from data collected over a 3-week period. No cross-reactivity was found when the assay was tested with a 700 nM sample of staphylococcal enterotoxin A. Although competitive immunoassays are usually used for small molecules, such as therapeutic drugs, the results demonstrate that relatively large molecules (SEB, 27 kDa) can also be assayed with the technique.     

Oligodeoxynucleotide-modified capillary for electrophoretic separation of single-stranded DNAs with a single-base difference.

We describe here a method of affinity capillary electrophoresis in which oligodeoxynucleotide (ODN) was immobilized onto the inner surface of the capillary. The immobilized ODN functioned successfully as an affinity ligand for sequence-based DNA separation. Six- or 12-mer ODN with a sequence complementary to one of the c-K-ras gene was used as an immobilized ligand. When the 12-mer ODN was used, the detection peak for the complementary ODN disappeared selectively, while the single-base mutant was detected as usual. In contrast, when the 6-mer ODN was used as the affinity ligand with a mixture of the complementary ODN and its single-base mutant, it was possible to detect both as completely separate peaks. That is, the separation mode was dependent on the base number of the immobilized ODN used as an affinity ligand.     

铌酸催化的苯甲醛与甲醇缩合反应

采用铌酸为催化剂,探索了该催化剂对苯甲醛与甲醇缩合反应的影响.优化反应条件是,催化剂用量为反应物质的量的5mol%,甲醇10mL(兼作溶剂),回流状态下反应2h,反应的产率和转化率分别达到94%、98.0%.该催化剂同样适用于其他醛(酮)与甲醇的缩合反应,可得到34%～89%的产率.所述方法操作简单、产率高、选择性好而且对环境友好,反应结束后,催化剂很容易回收,并能有效重复使用.     

汽车排放污染物的共振增强多光子电离光谱分析

汽车排放的主要污染物为CO,HC,NOx(x=1,2）,SO2,Pb,苯丙芘,固体颗粒等[1],其尾气的检测对维护人类自身健康具有十分重要的意义．共振增强多光子电离光谱（Resonant Enhanced Multi-Photonionization,REMPI）是一种超灵敏光谱检测技术,它的灵敏度比LIF（Laser InducedFluorescence）还要高．1979年,Brophy和Rentttner[2]提出了REMPI可以作为检测大气污染的方法．后来,不同的研究小组采用了不同的REMPI方案对大气污染类分子进行了测量研究［3-6]．由于采用可调谐染料激光器为光源,可以使用同一种染料对几种具有相近特征波长的分子进行同时测定．本文报     

紫外/可见光谱在有机光纤研制中的应用

有机光导纤维是近十几年来在新型光功能性高分子材料领域中的一支独秀.相对于玻璃光导纤维,有机光导纤维加工容易、口径大、轻而柔软、抗挠曲、抗冲击、耦合容易,更重要的因素是制作成本低和用途广泛.通常光导纤维是一种带包层的透明圆柱型的细丝.芯子的折射率高于包层并且是不变的,这种纤维称为突变型(SI)光纤.由于SI型光纤的带宽小,不能满足高信息量传输的需要,因而渐变型(GI)有机光纤得以发展.在这种光导纤维中,纤芯的折射率是呈抛物线型分布的,其轴心的折射率最大,折射率由纤维轴心沿径向到包层逐渐变小,在芯/包层界面处折射率无突变,光线在这种光纤的传播路径近似正弦波.沿正弦波处的折射率均小于轴心区的折射率.由于光速是反比于折射率的,因此当光沿着正弦途径传输时,其速度大于光沿着轴心传输的速度.于是,较长的光路被较大的光速所补偿,结果是光在正弦波处的传输时间与在轴心处的传输时间上没有大的区别,而脉冲加宽是正比于传输时间的差值,因此有望在GI型有机光纤中得到较小的脉冲加宽.GI型有机光纤的制备一般可在GI型有机预制棒的基础上通过熔融热拉技术拉制而成.因此,制备GI型有机预制棒及其折射率分布的检测成为关键步骤.折射率分布的测量方法有很多,如近场扫描法、折射近场法、切片干涉法等.本文首次介绍了将紫外/可见吸收光谱应用于预制棒折射率分布的定性测试上,得到了在预制棒芯区沿径向掺杂剂分子溴苯的吸收强度呈抛物线型分布.因测试折射率分布的其他方法较为繁杂以及受仪器的限制,所以利用紫外/可见吸收光谱这一非常普通的仪器来估计折射率分布的情况不失为一种简单易行的方法.     

Electrospray doxorubicin-loaded polycaprolactone-polyethylene glycol nanospheres/poloxamer-chitosan thermogel: A promising candidate for clinical applications

In recent years, polymer nanospheres have been considered as one of the most common materials in the drug delivery domain. In this research, polycaprolactone-polyethylene glycol (PCL-PEG) blend nanospheres were produced using the electrospray method to load doxorubicin. Also, these nanospheres can be used for injection in the treatment site by poloxamer-chitosan thermogel. In this research, PCL and PEG were used as raw materials to produce nanospheres. Then, doxorubicin was used for loading in nanospheres. The electrospray method was chosen as the method of nanosphere production. In the next step, poloxamer-chitosan thermogel was used for injection at the treatment site. In this method, Fourier transform infrared spectroscopy, scanning electron microscopy, and rheometer techniques were used to identify the compounds and properties of the obtained specimens. Also, the MTT test was used to investigate toxicity. The results showed that PCL-PEG polymer nanospheres were produced by loading doxorubicin using the electrospraying method with a diameter of 185 ± 23 nm. Also, these nanospheres were used for injection in the treatment site using poloxamer-chitosan thermogel. The amount of drug release in the PLX-CS (DOX-PCL-PEG)NSs was 63% in 144 h at medium pH 5.5. In the drug release system, the in-vitro method was utilized to study the release of PLX-CS (DOX-PCL-PEG) NSs. PCL-PEG nanospheres combined in poloxamer-chitosan thermogel polymer showed the controlled release of doxorubicin, therefore, the evaluated drug release system is considered a valuable perspective as an efficient and safe route for drug delivery in the target tissue and treating various types of cancer. This research can be used as a new method in drug delivery systems.     

Design of experiments for capillary electrophoretic enantioresolution of salbutamol using dermatan sulfate

Statistical experimental design was used for the optimization and for robustness evaluation of a capillary electrophoretic method developed for the enantioresolution of salbutamol. Dermatan sulfate was used as chiral selector. The goal of the study was to obtain an efficient and fast separation. An eight-run Plackett-Burman matrix was used during the optimization process for the screening of the factors and to adjust the experimental domain under study. Response surface methodology was adopted after the screening phase to obtain information about how the factors percentage of chiral selector, pH and voltage affected the considered responses resolution and analysis time. The Derringer desirability function, which makes it possible to combine results obtained for properties measured on different scales, was used to simultaneously optimize the two responses. Robustness testing was carried out using a Plackett-Burman matrix. The method was found robust as regards the response resolution while voltage and chiral selector were found to be critical factors for the robustness of analysis time response. The proposed CE method permitted the complete enantioseparation of racemic salbutamol and was applied to its chiral resolution in spiked urine samples.     

Strategies for the Analysis of Pharmaceutical Cocrystals Using HPLC with Charged Aerosol Detection

Several active pharmaceutical ingredients are currently being developed as pharmaceutical cocrystals as these systems often have superior properties compared to traditional pharmaceutical forms. Pharmaceutical cocrystal formers typically used are polar, small molecule acids or bases which often lack a UV chromophore. Their polar nature results in almost no reversed phase retention and their detection typically cannot be done with UV. Here we discuss approaches for the analysis of pharmaceutical cocrystals using HPLC columns designed for polar retention, ion pairing chromatography (IPC), and hydrophilic interaction chromatography (HILIC) using model cocrystal formers. Corona charged aerosol detection (CAD) was used to monitor the cocrystal formers. l-alanine was used as a model basic cocrystal former, and succinic acid and glutaric acid were used as model acidic cocrystal formers. The acidic cocrystal formers were adequately retained on a C18 column. Heptafluorobutyric acid was used as the ion-pairing reagent for l-alanine as it was unretained without the ion-pairing reagent. HILIC, a newer approach for polar compound retention, was also investigated. Using the HILIC mode, all three model cocrystal formers were retained adequately. Of all the approaches studied for the analysis of the cocrystal formers, HILIC appears to be the best choice as the same column can be used for both acidic and basic cocrystal formers. With IPC, the ion-pairing reagent permanently alters the column chemistry and dedicated columns are required for each ion-pairing reagent used. CAD detection provided a linear response in the 80–100% test concentration range for the analytes studied here.     

改性沥青中橡胶含量的高效液相色谱测定法

用高效液相色谱法测定了改性沥青中橡胶的含量。柱温30℃,检测波长222 nm,流动相为同等比例的正己烷、四氢呋喃和乙腈的混合液,UV检测器。该方法的相对标准偏差RSD≤1.5%,线性方程:y=800.94x+579.03,线性相关系数r=0.999 8。     

Use of 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel for automated preconcentration and selective determination of antimony(III) by flow-injection electrothermal atomic absorption spectrometry

Selective sorption of Sb(III) on a microcolumn packed with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel (DPTH-gel) has been used for determination of Sb(III). A flow-injection system comprising a microcolumn connected to the tip of the autosampler was used for preconcentration. The sorbed antimony was eluted with nitric acid directly into the graphite furnace and determined by AAS. The detection limit for antimony under the optimum conditions was 0.3 ng mL^–1. This procedure was used for determination of antimony in natural water, soil, vegetation, and a certified sample of a city waste incineration ash (BCR 176).