Characterization of OV-1/FFAP-mixture coated glass capillary columns used for the separation of free fatty acids

As an alternative to acid pretreated UCON and FFAP capillaries for the analysis of wide-boiling free fatty acid mixtures, OV-1 : FFAP phase mixtures were used on high-temperature silylated inert glass capillary columns. The HETP-carrier gas velocity curves, peak asymmetry factors, coating efficiency, gas phase and stationary phase contributions to the mass transfer resistance were determined for various OV-1 : FFAP ratios. Mixed-phase capillaries showed optimum performance at a 2 : 1 OV-1 : FFAP ratio. The thermal and long-term stability of OV-1-stabilized FFAP columns surpassed those of the UCON and pure FFAP reference column used.     

Evaluation of free hydroxyl radical scavenging activities of some Chinese herbs by capillary zone electrophoresis with amperometric detection

Due to the severe damage caused by free hydroxyl radicals (OH·) to cells and tissues, there is much interest in finding and studying effective and non-toxic OH· scavengers, including traditional Chinese herbs. In this paper, the simple and highly-sensitive technique of capillary zone electrophoresis with amperometric detection (CZE-AD) was used to study the OH· scavenging activities of aqueous extracts from some traditional Chinese herbs. Salicylic acid (SAL) was used as an OH· trap, and the content of OH· could be determined by assaying their products, 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA). The optimum conditions for CZE-AD for the determination of 2,3-DHBA and 2,5-DHBA were explored. The linearity ranges of 2,3-DHBA and 2,5-DHBA were 1.0 ×10^–7~1.0 ×10^–4 mol L^–1, and their detection limits were as low as 2×10^–8 mol L^–1, which were much better than the CE-UV method often used. The traditional Chinese herbs studied included Radix angelicae sinensis, Rhizoma coptidis, Ligustrum lucidum, Ligusticum wallichii, Radices glycyrrhizae and Semen plantaginis. The experiments showed that the aqueous extracts from all of the above traditional Chinese herds had free OH· scavenging activities, although to different degrees.     

Evaluation of recombinant green fluorescent protein, under various culture conditions and purification with HiTrap hydrophobic interaction chromatography resins

To determine the influence of various culture conditions, transformed cells of Escherichia coli expressing recombinant green fluorescent protein (GFPuv) were grown in nine cultures with four variable conditions (storage of inoculated broth at 4°C prior to incubation, agitation speed, isopropyl-β-d-thiogalactopyranoside [IPTG] concentration, and induction time). The pelleted cells were resuspended in extraction buffer and subjected to the three-phase partitioning (TPP) extraction method. To determine the most appropriate purification resin, protein extracts were eluted through one of four types of HiTrap hydrophobic interaction chromatography (HIC) columns prepacked with methyl, butyl, octyl, or phenyl resins and analyzed further on a 12% sodium dodecylsulfatepolyacrylamidegel. With Coomassie staining, a single band between 27 (standard GFPuv) and 29 kDa (molecular weight standard) was visualized for every HIC column sample. TPP extraction with HIC elution provided about 90% of the GFPuv recovered and eight-fold GFPuv enrichment related to the specific mass. Rotary speed and IPTG concentration showed, respectively, greater negative and positive influences on GFPuv expression at the beginning of the logarithmic phase for the set culture conditions (37°C, 24-h incubation).     

Non-aqueous capillary zone electrophoresis method for the analysis of paroxetine, tamoxifen, and their main metabolites in urine

The potential of non-aqueous capillary electrophoresis (NACE) was investigated for the simultaneous separation of paroxetine, tamoxifen, and their main metabolites. Baseline separation of the studied solutes was obtained on a  μm capillary using a non-aqueous buffer composed of 18 mM ammonium acetate and 1.1% acetic acid in 80:20 (v/v) methanol-acetonitrile, with a temperature and voltage of 22 °C and 15 kV, respectively. Clomipramine was used as internal standard. Aspects such as stability of the solutions, linearity, accuracy, precision and ruggedness were examined in order to validate the proposed method. Detection limits obtained for all the studied compounds ranged between 3.0 and 7.1 μg l⁻¹. The developed method is sensitive and robust and was used to determine paroxetine, tamoxifen, and their metabolites at clinically relevant levels in human urine. Before NACE determination, the samples were purified and enriched by means of an extraction-pre-concentration step with a pre-conditioned C₁₈ cartridge. Determination of these analytes in the urine of four females urines was demonstrated.     

Simultaneous Determination of Various Classes of Pesticides Using Micellar Electrokinetic Capillary Chromatographyin Combination with Solid-Phase Extraction

The potential of micellar electrokinetic capillary chromatography (MEKC) with UV-detection for the simultaneous determination of various selected pesticides in water samples was investigated. The developed method using solid-phase extraction showed high efficiency and good resolution with detection limits in the 0.2 to 0.5 ppm range. Comparison of several SPE cartridges demonstrates their suitability for the extraction of pesticides with different hydrophobicity achieving 5000-fold enrichment. The described method involving SPE procedure and MEKC separation enables the successful determination of a wide spectrum of pesticides in water in the range of maximum residue limits (MRLs).     

分子筛改性气—液毛细管柱及其性能考察

以原位合成法制备的分子筛膜对玻璃毛细管内壁进行改性后，成功地制备了常规口径及大口径分配ＳＣＯＴ柱，并对毛细管柱的性能进行了评价。     

Chromatographic evaluation of perphenylcarbamoylated β-cyclodextrin bonded stationary phase for micro-high performance liquid chromatography and pressurized capillary electrochromatography

Application of mono (6^A-N-ethylenediamine-6^A-deoxy) perphenylcarbamoylated β-cyclodextrin (β-CD) bonded stationary phase (CSP) in micro-high performance liquid chromatography (micro-HPLC) and pressurized capillary electrochromatography (p-CEC) was firstly presented. A series of racemic α-amidophosphonates were resolved in reversed- and normal-phase modes on this CSP. The investigated chromatographic parameters include retention factor (k′), separation factor (α) and resolution (Rs) of solutes. In addition, the structural variation of the solutes and the experimental factors affecting chiral separations have been examined, including the percentage of alcohol modifier, the linear velocity (u) of the mobile phase, electrical field strength, etc. Baseline separation was achieved for most of the entities. Hydrophobic interaction, steric effect and π-π interaction contribute to the possible mechanism. Comparative results indicate that higher Rs value up to 3.1 was found in micro-HPLC, higher efficiency up to 29,970 in p-CEC.     

The effect of interface deformation due to gravity on line tension measurement by the capillary rise in a conical tube

Much research has been done on line tension measurement and interpretation, and attempts have also been made to measure line tension with simple, cheap and reliable methods that do not require excessive sophistication. Of particular interest is the method of determining line tensions of solid–liquid–vapor systems from the capillary rise in a conical tube. This simple and relatively inexpensive method gives line tension values comparable to those reported in the literature obtained via highly sophisticated instruments or techniques such as the well known axisymmetric drop shape analysis technique. The absolute value of line tension obtained using the conical tube method and assuming a spherical liquid–vapor interface is larger but of the same order of magnitude (1 μJ m⁻¹) as that reported in the literature. A theoretical analysis presented herein shows that by including the deformation of the liquid–vapor interface due to gravity in the conical capillary analysis, the line tension value inferred from the experimental data is reduced by approximately 50% and compares better with values in the literature obtained using other sophisticated methods. Thus a relatively simple, cheap, accurate and reliable method of line tension measurement has been advanced.     

聚丙烯酰胺双向凝胶电泳法分析变色人发角蛋白组成

报道了一种用双向聚丙烯酰胺凝胶电泳分析经Ｓ－羧甲基化修饰的变色人发角蛋白样品的方法，以含８ｍｏ１／Ｌ脲变性凝胶电泳做第一向，ＳＤＳ－ＰＡＧＥ做第二向。不同处理的变色人发得到有差别的双向电泳图谱，即不同处理方法得到的人发蛋白质组成有差异。以此可做为人发变色处理的一个定性方法。     

毛细管电泳在拮抗药物对氨基苯甲酸、对羟基苯甲酸和磺胺分析测定中的应用

本文报道了一种用毛细管区带电泳法(CZE)分离与测定对氨基苯甲酸、对羟基苯甲酸及磺胺类药物的新方法.电泳条件为:用 20mmol/L硼砂-20mmol/L H_3PO_4-20 mmol/Lβ-环糊精-4％乙醇(pH 7.0)作电泳液,L-抗坏血酸为内标,280nm为检测波长,样品由电进样方式(10kV/10s)引入毛细管(51.2 cm×50μm i.d.,有效分离长度为 38.5 cm).在24.5°C下,6 min内三者可达基线分离(电泳电压 25kV),且在一定范围内可进行定量分析,保留时间(Tr)及A_(样品)/A_(内标)的RSD值分别小于1.0％和5.0％.本法的建立为研究这三者共存于高等动物及微生物体内时的生理作用提供了一种可共选择的新方法.