Flow injection chemiluminescence determination of l-cysteine in amino acid mixture and human urine with the BrO3 −–quinine system

In this paper, a novel flow injection chemiluminescence (CL) determination of l-cysteine is proposed. The method is based on the CL reaction of l-cysteine and KBrO₃ in acidic medium. The CL intensity was greatly enhanced in the presence of quinine. The CL intensity was linear with l-cysteine concentration in the range of 0.2–80 g L^–1, and the detection limit was 0.1 g L^–1 (3). A complete analysis, including sampling and injecting, could be performed in 1 min, giving a throughput of about 60 h^–1. The relative standard deviation was 1.6% for 0.8 g L^–1 l-cysteine (n=11). The proposed method was satisfactorily applied to the determination of cysteine in an amino acid mixture and human urine. The mechanism of the CL reaction is also discussed.     

奎宁修饰型Pt/Al2O3催化丙酮酸乙酯不对称加氢反应：乙酸溶剂与甲苯溶剂的比较

采用奎宁修饰型Pt/Al_2O_3作为加氢催化剂在常温常压下比较了乙酸和甲苯溶剂中丙酮酸乙酯的不对称加氢与一般的加氢反应的反应结果;研究了反应对映选择性与底物转化率的关系、丙酮酸乙酯用量对产物对映选择性的影响、三乙胺的作用以及乙酸-甲苯混合溶剂的使用. 实验结果表明, 乙酸作为反应溶剂的性能优于甲苯且溶剂化作用强于甲苯;两种溶剂中的不对称加氢反应均存在初始过渡期, 以乙酸为溶剂时, 催化反应速度较快;在乙酸溶剂中底物用量对产物对映纯度影响不大, 在甲苯溶剂中底物用量具有最佳值;在乙酸溶剂中加入三乙胺能显著提高反应的对映异构体选择性而在甲苯溶剂中则没有促进作用.     

恒波长同步荧光淬灭法测定食品中苏丹红Ⅱ的研究

本文建立了恒波长同步荧光淬灭测定苏丹红Ⅱ的新方法.研究表明,苏丹红Ⅱ对硫酸奎宁的荧光有淬灭作用,通过Stern-Volmer方程的计算和紫外吸收光谱研究,得到苏丹红Ⅱ对硫酸奎宁荧光的淬灭机制主要为动态淬灭,且淬灭程度与苏丹红Ⅱ的含量呈线性关系.当△λ=30 nm时,该方法的线性范围为1.0×10-6 ～5.0×10-4mol/L,检出限为2.393×10-11 mol/L.     

First quinine-based aryl phosphite: synthesis and application in the Pd-catalyzed enantioselective rearrangement of allylic thiocarbamate

New quinine-based polyfunctional aryl phosphite was synthesized. The phosphorus center in the new compound is characterized by a large cone angle ( = 190°). The new compound can be used in the Pd-catalyzed enantioselective rearrangement of cyclic O-allylic thiocarbamate into S-allylic thiocarbamate in an optical yield of up to 47% with a quantitative conversion.     

离子对色谱法研究吡咯并喹呤醌与D-丝氨酸反应的化学动力学

D-丝氨酸(DSer)作为一种新的神经递质存在于胶质细胞,在中枢神经系统疾病中发挥重要的作用;吡咯并喹呤醌(PQQ)能够促进神经因子的产生和神经保护作用。采用离子对色谱法测定吡咯并喹呤醌(PQQ)与DSer反应中游离PQQ的浓度,通过化学反应动力学研究PQQ与DSer的作用,为PQQ在神经递质的调节作用机制提供重要的信息。采用四丁基溴化铵为离子对试剂,PQQ与DSer孵育反应后各物质在Amethyst C18-P柱上的分离度较好,平均回收率为94.2%～99.3%,相对标准偏差为1.05%～2.03%。PQQ-DSer反应的平均速率常数分别为0.032 h~1 (25 ℃)、0.07 h~1(37 ℃)、0.17 h~1(50 ℃);平均反应活化能为54.7 kJ/mol;半衰期分别为22.0 h(25 ℃)、9.8 h(37 ℃)和3.99 h(50 ℃)。动力学结果显示PQQ对脑内DSer的平衡具有重要的调节作用。该方法简便、可靠。     

Direct Photochemical Titration of a Fluorescent Compound

Abstract

The direct titration of quinine with ultraviolet photons is reported; previous titrations have used an intermediate photogenerator. A single mercury vapor arc was used to both photolyze the sample and to induce fluorescence; the latter is used to follow the course of the titration. Linear calibration plots were obtained over the range of 0.13 to 3.33 ppm of quinine with relative standard deviations as low as 1.6%.     

4th order derivative spectrophotometric determination of quinine in soft drinks

A method is developed for the 4rd order derivative spectrophotometric determination of down to 1–6 g/ml of quinine. This method has been applied to its determination in soft drinks. Comparison are made between this method and a spectrofluorimetric method.     

奎宁与过渡元素钨硼多金属氧酸盐中配位水的取代反应研究

报道了钨硼杂多阴离子[BW11O39M(H2O)]^7-(M=Co^2 ,Cu^2 ,Ni^2 )中配位水与奎宁的取代反应，利用UV—vis和ESR谱进行了表征，并且测定了配合物的旋光度，结果表明奎宁取代了杂多阴离子中的配位水，与杂多阴离于中的取代过渡金属原子形成了配位键．奎宁与杂多阴离子键合生成的杂多配合物，仍然具有旋光活性，其中含Cu^2 的奎宁杂多化合物保持了奎宁的左旋特性，而含Ni^2 的奎宁杂多配合物由左旋变为右旋。并初步探讨了取代反应的机理。     

4—甲基伞形酮荧光猝灭法测定苦味酸

本利用苦味酸对４－甲基伞形酮荧光的猝灭的猝灭效应，提出了一种新的测定苦味酸的方法，线性范围为１×１０＾－４－１×１０＾－８ｍｏｌ／Ｌ，以３σ衡量，检出限为８×１０＾－７ｍｏｌ／Ｌ，用于药品奎宁的间接测定和水样中苦味酸的直接测定，结果令人满意。