高配位双环氮氧杂有机锡化合物在二甲亚砜溶剂中的酸性解离常数

本文报道了在DMSO溶剂中利用Bordwell指示剂重迭法测定六种高配位双环氮氧杂有机锡化合物的α-CH的酸性离解常数(pKa)的方法, 并对配合物的结构与其α-CH酸性的关系进行了讨论。     

Simultaneous determination of noradrenaline and dopamine in Portulaca oleracea L. by capillary zone electrophoresis

A simple and rapid capillary electrophoretic method was developed for the simultaneous determination of noradrenaline (NA) and dopamine (DA) in Portulaca oleracea L. The buffer solution used in this method was 40 mM tris (hydroxymethyl) aminomethane (Tris)-H3PO4 at pH 2.00 containing 15% methanol. The effects of pH value, organic modifier, and applied voltage were investigated. The linear ranges of NA and DA were 0.5-100 microg/mL (r=0.9952) and 6.25-200 microg/mL (r=0.9992), respectively. The relative standard deviations of the corrected peak area were 6.73% and 4.26%, respectively. NA and DA in Portulaca oleracea L. were simultaneous determined successfully within 5.6 min. In this way, the contents of NA and DA in different parts (stem, leaves, and seeds) of P. oleracea L. and in different extracts of leaves with different solvents (distilled water, 50% methanol, and methanol) were studied.     

Identification and determination of aesculin and aesculetin in ash barks by capillary zone electrophoresis

Summary A capillary zone electrophoresis method for identification and determination of aesculin and aesculetin has been established using borate-phosphate buffer containing 30% ethanol with on-column UV detection. A detailed investigation of the influence of changes in borate concentration, pH, applied voltage, temperature and organic modifier was then carried out. For both aesculin and aesculetin, a linear plot of migration time (MT) against borate concentration was obtained, and ln[measured peak area (MA)] and lnMT both gave linear plots against ln(applied voltage) with correlation coefficient r>0.999, which also resulted in a linear correlation between MA and MT (r≥0.9998) under varied voltage. Ethanol as organic modifier to the background electrolytes helped in separating aesculin and aesculetin from other components in ash barks. The reproducibility with relative standard deviation in MT and in normalized peak area(NA) and linearity based on NA against concentration were evaluated. Finally, the method was successfully applied to monitor the quality of different ash barks and to compare the effect of sample preparation on content of bioactive components in ash bark. Results indicate that CZE promises to be applicable to quality control of traditional Chinese medicines containing aesculin and aesculetin.     

氨基酸衍生物在毛细管区带电泳下的分离研究

采用新合成的荧光试剂咔唑-9-乙基氯甲酸酯作为柱前衍生试剂,利用毛细管区带电泳法对衍生氨基酸进行分离,考察了该试剂用于毛细管区带电泳法进行氨基酸分离的关键条件,实现了12种氨基酸的快速基线分离.     

毛细管区带电泳法测定血浆中的苯妥英钠

 建立了以毛细管区带电泳测定血浆中苯妥英钠含量的方法。此法具有良好的重现性和线性关系 ,日内、日间的平均相对标准偏差分别为 3.1%和 4 .7% ,平均回收率大于 95 % ,标准曲线的相关系数为 0 9985 ,是一种简便、快速、准确、灵敏的测定方法 。     

Capillary zone electrophoretic determination of tosufloxacin and trovafloxacin in urine

Summary A simple and rapid capillary zone electrophoretic method with UV detection has been developed for determination of tosufloxacin and trovafloxacin. The separation was performed in fused-silica capillaries (57 cm length × 75μm i.d.); the running buffer was 35mm borate + 35mm phosphate buffer solution, pH 8.6, containing 6% (v/v) acetonitrile. The applied potential was 15 kV, the temperature 30°C, and detection was at 262 nm. Piromidic acid was used as the internal standard. Response was linearly dependent on concentration in the range 1.0–120.0 μg mL⁻¹ and the detection limit was 0.2 μg mL⁻¹ for both compounds. The analysis was highly reproducible (RSD between 3.41 and 1.25%). The method was applied to the determination of tosufloxacin and trovafloxacin in human and rat urine. The method was validated by using HPLC as a reference method. Recovery was between 96.8 and 102%.     

Characterization of antithrombin III from human plasma by two-dimensional gel electrophoresis and capillary electrophoretic methods

The isoforms distribution of the glycoprotein antithrombin III (ATIII) derived from human plasma was investigated by means of isoelectric focusing (IEF) in polyacrylamide gels with immobilized pH gradients (IPG) and two-dimensional gel electrophoresis (2-DE) as well as capillary electrophoretic methods. It turned out that the presence of high concentrations of chaotropics (urea, thiourea) and zwitterionic detergents (3-[(3-cholamidepropyl)dimethylammonio]-1-propanesulfonate (CHAPS)) was decisive for attaining good resolution of the protein isoforms. Resolution by IPG-IEF was obtained with excellent reproducibility and pI differences down to 0.01 pH units could be distinguished. ATIII-alpha and ATIII-beta-fractions preseparated by heparin affinity chromatography showed an analogous but shifted spot pattern consisting each of one major and three minor isoforms. The main isoforms of ATIII-alpha and ATIII-beta exhibit pI values of 5.18 and 5.32, respectively, both values determined in the presence of high concentrations of urea. The pI difference of 0.14 pH units correspond to the effect of two sialic acids absent in ATIII-beta. The formation and occurrence of ATIII dimers and trimers turned out to be dependent on the sample preparation. The results obtained by 2-DE were compared with those of capillary zone electrophoresis (CZE) and capillary IEF (CIEF). Quantitative analysis regarding the CZE separated isoforms of plasma derived ATIII yielded a content of about 70% ATIII-alpha main isoform and about 6.6% of ATIII-beta. The pI values of ATIII determined by CIEF with internal calibration were in fair agreement with the pI values of the main isoforms achieved with 2-DE.     

Protein adsorption in fused-silica and polyacrylamide-coated capillaries

The model proteins cytochrome c, myoglobin, ovalbumin, and beta-lactoglobulin were investigated with regard to their adsorption properties on capillaries for electrophoresis. The model compounds were selected to cover a wide range of properties. Cytochrome c is a basic protein (isoelectric point (pI): 9.6; M(r): 11.7 kDa), beta-lactoglobulin is rather acidic (pI: 5.4, M(r): 18.4 kDa), myoglobin was chosen as a neutral reference protein (pI: 6.8-7.4, M(r): 17.8 kDa), and ovalbumin (pI: 5.1, M(r): 45.0 kDa) was selected as a relatively larger analyte. First, the pH dependence of adsorption was investigated for the bare fused silica. A clear correlation to the respective pIs was noted. For myoglobin and ovalbumin, none or negligible adsorption was found above the pI, whereas strong adsorption was noted just below this parameter. Cytochrome c and beta-lactoglobulin already showed distinct adsorption above their pIs. However, none of the proteins showed any significant adsorption more than one pH unit above the pIs. For linear polyacrylamide-coated capillaries, a decreased but not a complete lack of adsorption was observed. Here, pH-dependent adsorption was noted as well. Regeneration of the capillaries by rinsing with buffers containing 200 mM SDS was also investigated. This method was completely successful for myoglobin, but that too for only freshly-adsorbed protein. After a storage time of 24 h and due to the aging of the adsorbate, a sufficient regeneration was no longer possible.     

A Novel Method for Quantification of Circulating DNA in Serum by Capillary Zone Electrophoresis

In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma.