茶叶中7种有机磷农药残留量的同时测定

采用配有FPD检测器的气相色谱仪测定茶叶中多种有机磷的农药残留量. 对样品的前处理进行了探讨, 结果表明, 样品用乙酸乙酯和少量苯提取, 过硅胶-活性炭柱净化, 同时用乙酸乙酯和少量苯洗脱, 7种有机磷在HP-35柱上得到很好的分离, 且方法准确快速、重现性、回收率好, 符合实际工作需要.     

毛细管气相色谱法测定5种中草药中有机氯农药的残留量

建立了怀牛夕等 5种中草药中六六六及滴滴涕异构体含量的气相色谱分析方法。样品以石油醚 +丙酮在索氏提取器中提取 ,提取液以浓硫酸净化。采用SE 30弹性石英毛细管柱分离样品 ,GC ECD检测六六六、滴滴涕农药的残留量。方法的线性范围为 5 .7× 10 - 7～ 2 .8× 10 - 4μg ;最小检测量为 1.3× 10 - 1 4～ 2 .5×10 - 1 2 g ;加样平均回收率为 88.8%～ 99.1% ;RSD为 0 .9%～ 5 .3%。     

测接触角法确定偶联剂的最佳用量

偶联剂是一类能在无机填料和聚合物基材之间形成“分子桥”、改善两者之间相容性或提高两者之间相互作用能力的化合物。将经偶联剂改性的无机填料填充到聚合物中可以制得成本低、性能好的复合材料。由于偶联剂用量多少将对复合材料的性能产生较大影响,因此建立一种准确、简便地确定偶联剂最佳用量的方法有着十分重要的理论和实际应用意义。     

牛血清白蛋白与十二烷基硫酸钠作用的机理

利用电动势法得到了牛血清白蛋白(BSA)与十二烷基硫酸钠(SDS)相互作用的结合等温线. 通过四阶导数紫外光谱法和荧光光谱法研究了相互作用过程中芳香族氨基酸残基微环境极性的变化. 通过研究发现, 随着SDS浓度的逐渐增大, SDS在BSA上的平均结合数(v)逐渐增大, 色氨酸(Trp)残基所处微环境的极性在减弱后保持基本不变, 酪氨酸残基所处微环境的极性在明显增强后稍有减弱, 苯丙氨酸残基所处微环境的极性略有增强. 结果表明, 当v由0增大到14时, SDS主要结合在BSA的Trp-213附近并逐渐形成聚集体, 从而诱导BSA由结构域ⅡA 开始逐渐展开. 此后, SDS呈正协同作用的特点与BSA 结合, v急剧增大. 当v约为302 时, SDS在BSA上的结合基本达到饱和, BSA的构象趋于稳定.     

Sol-gel entrapment of monoclonal anti-atrazine antibodies

We report the successful doping of a sol-gel matrix with an antibody, retaining its ability to bind free antigen from an aqueous solution. The particular system described is monoclonal anti-atrazine mouse antibody which was entrapped in SiO₂ sol-gel matrices, prepared from tetramethoxysilane by several methods. Atrazine was selected as a model compound for this study, within the framework of the development of immunochemical-based methods for monitoring pesticide residues and other organo-synthetic environmental contaminants. Nanogram quantities of atrazine were applied on SiO₂ sol-gel columns doped with this antibody, and the amount of eluted antigen was determined by Enzyme Linked ImmunoSorbent Assay (ELISA). Under appropriate sol-gel-forming conditions, high amounts of atrazine were bound to the sol-gels, ranging between 60% and 91% of the amount applied to the column. The combination of the properties of the sol-gel matrix (e.g., stability, inertness, high porosity, high surface area and optical clarity), together with the selectivity and sensitivity of the antibodies, enable extension of this feasibility study to development of a novel group of immunosensors which could be used for purification, concentration and monitoring of a variety of residues from different sources.Contribution from the Agricultural Research Organization (ARO), Bet Dagan, Israel. No., 1697-E, 1995 series.     

甲胺磷离子选择性电极的研制及其应用

以四苯硼钠与甲胺磷在盐酸介质中生成的离子缔合物为电活性物质,首次研制出一种甲胺磷PVC涂层玻璃电极。并对该电极的响应机理及性能进行了研究。实验表明,该电极的Nernst响应范围为1×10-2~1×10-4(φ),斜率为50.28 mV/pφ。该电极响应迅速,重复性好,用于蔬菜中残留甲胺磷的测定,方法快速、准确,结果满意。     

Fluorimetric determination of the fungicide benomyl after solvolysis

A simple spectrofluorimetric method for the determination of the fungicide benomyl in grapes is described. Benomyl is rapidly solvolysed in organic solvents to give the highly fluorescent metabolite carbendazim. Solvent effects on the spectral shape and their influence on analytical performance are studied. DMF was found to be the best solvent. The method is sensitive to 12 ng/ml benomyl, and has an RSD at the 0.5 g/ml level of 2.2%. The method is suitable for determining benomyl in spiked grapes, with recoveries in the range 97 to 104%.     

气相-质谱法测定粮谷中恶草酮的残留量

 应用微量化学法和固相萃取技术 ,建立了粮谷中恶草酮残留量的气相 质谱 (GC MS)测定方法。用苯 正己烷 (体积比为 1∶1)萃取 ,中性氧化铝小柱净化。净化液用GC MS测定 ,采用外标法定量。恶草酮在大米中的回收率为 90 4%～ 115 .7% ,RSD为 2 %～ 6 % ,在玉米中的回收率为 81 3%～ 10 9 7% ,RSD为 4%～ 9% ,最低定量检出限为 0 0 0 5mg/kg。该法快速、灵敏、准确 ,各项技术指标均满足农药残留检测的要求。     

Amino acid end-group in commercial heparin. III. Determination of the number of amino groups of amino acid and hexosamine residues per heparin molecule

The reactions of heparin with 2,4,6-trinitrobenzenesulfonic acid (TNBS) were studied spectrometrically. Seven different commercial heparins were used in this study. The amino groups react with TNBS to form equimolar amounts of trinitrophenylated (TNP) amino groups and bisulfite ions. The TNP-amino groups further react with bisulfite ions to form the monosubstituted anionic sigma complex. The absorption spectrum with two maxima at approximately 350 nm and approximately 420 nm, characteristic of either the TNP-amino groups or the complex, was analyzed for the reaction of TNBS with heparin. It was shown that the reactivities of TNBS with amino groups from α-amino acid and hexosamine residues are greatly different. By combining the results of the reaction kinetics and the reaction of heparin with Sanger's reagent, the number of the α-amino groups and the free amino groups in hexosamine residues were determined. These data have been performed with a range of heparins from different commercial sources, of different activities and physical characteristics. No correlation was found between the free amino contents of these heparins and biological potency. © 1993 John Wiley & Sons, Inc.     

改性生物凝胶对重金属离子的吸附性能研究

以桔子汁加工残渣为原料,制备钙型和氢型生物凝胶作为吸附剂,用于去除水溶液中的重金属离子.结果表明,上述凝胶在水溶液中稳定性较好,对重金属离子的吸附性能优良.钙型凝胶的吸附选择性顺序为:Fe3 ＞Pb2 ＞Cd2 ＞Zn2 ,饱和吸附容量分别为:Pb2 、Cd2 、Zn2 均为约1.1mmol/g、Fe3 为1.5mmol/g;氢型凝胶的吸附选择性顺序为:Pb2 ＞Zn2 ＞Cd2 .钙型凝胶对Fe3 的吸附行为明显不同于氢型凝胶,钙型凝胶以离子交换机理以及Fe3 与Ca2 之间的共沉淀作用为主;而氢型凝胶对Fe3 的吸附则以离子交换机理为主.