以1,1,1-三(N-甲基-N_苯基氨基羰甲氧甲基)丙烷为载体的钙离子选择电极

报道了以三脚架化合物1,1,1_三 (N_甲基_N_苯基氨基羰甲氧甲基 )丙烷 (TMPP)为载体的钙离子选择电极的研制;探讨了增塑剂、载体浓度、pH等因素对电极性能的影响 ;结果表明电极对钙离子有较好的近能斯特响应 ,相应的斜率为27.6 mV/pcCa2+ ,线性响应范围为5×10-5 ～5×10-2 mol/L,检出限为2.3×10-5mol/L ;电极在pH4～13范围内具有强的抗干扰能力 ,并具有很好的重复性和稳定性 ;该电极作为钙离子选择电极 ,用于乳酸钙口服液中钙含量的测定 ,取得了满意的结果     

两性离子流动相测定杂多酸中的磷酸根、氯离子和硫酸根

采用离子色谱法测定杂多酸中痕量阴离子。由于常规的淋洗液(如Na2CO3,NaOH)呈碱性,使杂多酸迅速分解生成磷酸根,致使测定结果偏高。实验通过在常规淋洗液中加入适量两性离子后,调节淋洗液的pH为中性,从而能准确测定杂多酸中磷酸根氯离子和硫酸根的含量值。经过比较分别用去离子水和流动相稀释的样品中磷酸根的测定结果,确定淋洗液的最佳条件为2.5mmol/LNa2CO3-9.0mmol/LCHES,在该条件下测定,快速、准确、灵敏,且有较好的灵敏度和重现性。     

Method Development for the Speciation of Chromium in River and Industrial Wastewater Using GFAAS

A simple, sensitive and inexpensive method for the speciation of Cr(VI) and Cr(III) in river and industrial wastewater was developed, optimized and validated. Samples were collected, filtered and then chromium species were determined in the filtrate. In the filtrate, total Cr was determined directly by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). A portion of the filtered sample was buffered to pH 6.4, extracted with Amberlite LA-2/MIBK and finally Cr(VI) was determined in the organic extract and Cr(III) in the aqueous phase using GFAAS. The method was evaluated by analysis of the certified reference material, CRM 544, and good accuracy was obtained. The limit of detection for Cr(VI) and Cr(tot)/Cr(III) was found to be 0.30 and 0.08 µg L⁻¹, respectively, and a precision expressed as relative standard deviation of better than 11% was achieved for nine replicates. A number of water samples from the Tinishu Akaki River, Ethiopia, and wastewater samples from a chemical plant in Germany, were analysed. In addition to the GFAAS method, Cr(tot) was also determined using ICP-MS (in CRM 544, lyophilized water, and Tinishu Akaki River water samples) and Cr(tot) and Cr(VI) using UV-VIS spectrophotometry (in CRM 544 and industrial wastewater samples). Good agreement between the different methods was found.     

D072型树脂脱除过氧化氢中金属阳离子的工艺研究

实验考察D072型阳离子交换树脂在交换柱中脱除过氧化氢中微量金属阳离子的动态行为．通过改变料液流速、高径比、料液中交换离子浓度及料液组成等参数，绘制不同条件下的透过曲线，以此考察D072型树脂对过氧化氢中金属阳离子的动态交换性能，从而确定适宜的工艺条件，为工业化生产提供科学依据．     

Simultaneous Determination of Oxytetra- cycline, Doxycycline, Tetracycline and Chlortetracycline in Tetracycline Antibiotics by High-Performance Liquid Chromatog- raphy with Fluorescence Detection

A simple, rapid and sensitive high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of oxytetracycline, doxycycline, tetracycline and chlortetracycline was developed, and successfully applied to the analysis of commercial tetracycline antibiotics. The separation was performed on a reverse-phase C₁₈ column with a gradient elution composed of methanol and sodium acetate buffer (containing disodium ethylenediaminetetraacetate and calcium chloride, pH 8.10) as the mobile phase, and fluorescence detection at 532 nm (excitation at 380 nm). The detection limits for oxytetracycline, doxycycline, tetracycline and chlortetracycline were 0.1, 0.5, 0.3 and 0.4 g L^–1, respectively. Data with respect to precision and accuracy were reported and discussed.     

Topographical properties of polymer films deposited in capillaries for electrophoretic separations of large organic molecules

Topography and thickness of hydrophilic polymer coatings of fused-silica capillaries for capillary electrophoresis (CE) were investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry. Three hydrogels, poly(2-hydroxyethyl methacrylate) [poly(HEMA)], poly(diethylene glycol monomethacrylate) [poly(DEGMA)], and poly(triethylene glycol monomethacrylate) [poly(TEGMA)], were deposited using two procedures, either by simple physical sorption of the polymers, or by derivatization of the capillary wall surface with glycidyl methacrylate (EPMA) followed by polymerization of the appropriate monomers. The performance of the modified capillaries was tested under CE conditions (decrease in the electroosmotic flow, EOF dependence on pH, separation of milk and standard proteins). It has been found that the most important property of the polymer coating is its thickness, whereas its topography and the degree of its hydrophobicity are less significant. Film deposition by physical adsorption is preferable to polymerization on the derivatized surface.     

The calculation of retention and selectivity in reversed-phase liquid chromatography II. Methanol-water eluents

Summary To calculate retention in reversed-phase, high-performance liquid chromatography a method based on the molecular structure of the analyte and the characteristics of sorbents and mobile phases has been employed. Characteristics of different ODS-columns in water-methanol eluents have been determined.     

Supported Liquid Membrane Work-Up of Blood Plasma Samples Coupled On-Line to Liquid Chromatographic Determination of Basic Antidepressant Drugs

An automated sample pretreatment of human blood plasma for liquid chromatographic determination of three antidepressant drugs, dibenzepine; a tricyclic antidepressant (TCA), reboxetine; a selective noradrenaline reuptake inhibitor (SNRI) and fluvoxamine; a selective serotonin reuptake inhibitor (SSRI), based on supported liquid membrane (SLM) for unsurpassed sample clean-up and analyte enrichment, has been developed. The chromatograms after enrichment of plasma blank and aqueous blank are virtually indistinguishable. The entire analytical procedure revealed good linearity and low detection limits of 5, 15 and 20 ng mL^–1 for dibenzepine, reboxetine and fluvoxamine, respectively. No carry-over effects were noted. The repeatability of extraction at three concentrations in the range 40–150 ng mL^–1 for the three drugs was between ca. 3% and 7% as relative standard deviation. The reproducibility relative standard deviation during three different days (replacing the membrane each day) was not significantly higher.     

Theoretical study of the effect of frit quality on chromatography using computational fluid dynamics

Summary Frits at both ends of a chromatographic column, especially for a preparative column, have significant influence on the flow distribution within the column and thus the column efficiency. However, frits have received little attention from chromatographers in the past. Here a theoretical study was conducted with the aid of CFD software FLUENT to investigate the effect of frits on the performance of homogeneous and heterogeneous chromatographic columns. A dimensionless number,FQ, was applied to characterize frit quality. This study visualized how frit quality affects the flow distribution and the concentration band, the shape of eluted pulse at the colum exit and column efficiency. Simulation results show that the development length of the flow distribution is related toFQ but has nothing to do with the packing heterogeneity. The curvature of the concentration band in a column depends onFQ and packing quality. This study shows column efficiency can be improved significantly by increasingFQ and/or frit permeability.     

Molecular recognition properties of salicylic acid-imprinted polymers

Summary Two molecularly imprinted polymers (MIP) have been prepared using the acidic drug salicylic acid, which can form intramolecular hydrogen bond, as the template and acrylamide or 4-vinylpyridine as the functional monomer. HPLC was used to evaluate the binding performance of the MIP for the template and for several analogues. The results showed that the MIP (P₂) prepared using acrylamide as the functional monomer had no molecular imprinting effect whereas that (P₁) prepared using 4-vinylpyridine as the functional monomer had a significant molecular imprinting effect. The reason the molecular imprinting effect was different for the two MIP was elucidated and the molecular recognition properties of P₁ were studied in detail. It was confirmed that electrostatic interaction played an important role in the molecular recognition of P₁. Scatchard analysis showed that two types of binding site with distinctly different affinity were formed in P₁. Their dissociation constants were estimated to be 7.6×10⁻⁵ mol L⁻¹ and 3.2×10⁻³ mol L⁻¹, respectively. Because P₁ has high affinity and selectivity for salicylic acid not only in organic systems but also in water-containing systems, it gives P₁ the potential for use in the enrichment, separation, and detection of salicylic acid in biological fluids.