Preparation and thermal analysis of synthetic malachite CuCO3·Cu(OH)2

The synthesis of malachite CuCO₃·Cu(OH)₂ or Cu₂CO₃(OH)₂ was studied through titrations of copper(II) salt solutions with a solution of sodium carbonate at different temperatures. The precipitates were characterized by TG, IR and chemical analysis. The composition varies depending on thepH of the solution and the temperature. Purer malachite was synthesized by simple mixing of a solution of copper(II) nitrate or sulfate with a solution of sodium carbonate at 50°C.The kinetics of the thermal decomposition of synthetic malachite was described by eitherR ₃ orA _m(m=1.2–1.4) law, according to TG analysis, both isothermal and nonisothermal. The Arrhenius parameters determined using three different integral methods showed the kinetic compensation effect, which is correlated to the working temperature interval analyzed.The authors thank Mr. H. Takemoto for analyzing kinetics of the thermal decomposition of synthetic malachite.     

Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion‐Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH,Dopamine and Ascorbic Acid

Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis.     

动力学电位法测定硼

本文根据硼酸，苯乙醇酸，孔雀绿形成三元离子缔合型配合物的反应，用孔雀绿离子选择性电极监测反应速率，在最佳实验条件下，用固定时间法，电位变化与硼量在０．２－５．０μｇ／ｍＬ范围呈线性关系，用於测定标准钢样和玻璃标样中的硼，结果与标准值十分接近。     

基于金属有机框架水凝胶的一步式快速富集检测养殖水体中孔雀石绿北大核心CSCD

孔雀石绿是一种三苯甲烷类化合物,在水产品饲养中对疾病的防治有着不错的疗效,但因对人体健康有危害而被列为禁用药。由于实际样品中成分复杂,对于此类染料的检测方法难以同时兼具富集性好、灵敏度高且方便快速的优点。该工作制备了金属有机框架材料(MOF),采用MOF纳米材料掺杂的水凝胶(PAAM-SA/MOF)对养殖水体中的孔雀石绿进行吸附研究。采用一系列表征手段对MOF、PAAM-SA和PAAM-SA/MOF的微观形貌进行分析,结果表明吸附材料已成功合成。通过优化水凝胶吸附剂用量、吸附时间、孔雀石绿溶液pH、吸附温度、孔雀石绿溶液初始浓度等吸附萃取条件,使溶液中的孔雀石绿基本完全吸附在水凝胶中,在最优条件下,吸附效率最高可达97%。此外,采用不同极性的有机溶剂对吸附的孔雀石绿进行洗脱,通过优化洗脱液体积,脱附率最高达99%。在最佳条件下,该方法在高、中、低3个水平下的样品加标回收试验中回收率达到84.8%~118.1%,相对标准偏差小于5.1%,方法的检出限为0.083μg/L(S/N=3),定量限为0.25μg/L(S/N=10)。该方法简化了前处理过程,结合了MOF和水凝胶这二者各自的优点,添加的MOF材料可以在水凝胶体系中发挥其良好的吸附性,既解决了传统的MOF材料因粒径太小而回收率低的难题,便于吸附后直接提取,同时也解决了纯水凝胶吸附效率较低的问题,整体上提高了吸附效率和可回收性。实际样品测试表明该新型水凝胶吸附材料可用于养殖水体中孔雀石绿的快速萃取和检测,在食品检测领域具有很大潜力。     

A New Spectrophotometric Method for the Determination of Ascorbic Acid Using Leuco Malachite Green

A new simple and sensitive and selective spectrophotometric method has been developed for the determination of ascorbic acid (AA) at trace level using a new reagent, leuco malachite green (LMG). AAreacts with potassium iodide‐iodate solution under acidic conditions to liberate iodine and the liberated iodine selectively oxidizes LMG to MG dye. The colour of the dye was measured at 620 nm. Beer's law is obeyed over the concentration range of 0.8–8 iμg μAA per 25 mL of final solution (0.032–0.32 ppm). The apparent molar absorptivity and Sandell's sensitivity of the method were found to be 2.98 × 10⁵ l mol⁻¹ cm⁻¹, 0.0042 μg cm⁻², and respectively. Statistical treatment of the experimental results indicates that the method is precise and accurate. The method is free from interference of common ions and many of the ingredients commonly found in pharmaceuticals. The reliability of the method was established by parallel determination against Leucocrystal violet (LCV) method. The method described was satisfactorily applied for the determination of AA in fruit juices, pharmaceuticals and biological samples.     

数字图像法测定养殖水中的孔雀石绿

建立一种简单、可靠的养殖水中孔雀石绿的数字图像检测方法。以1-己基-3-甲基咪唑四氟硼酸盐离子液体富集水样品,再用手机拍照获取样品信息,最后用数字图像结合多层感知器神经网络定量分析孔雀石绿的含量。该法测定结果的相对标准偏差不大于6%(n=5),加标回收率为97.8%~103.0%。该方法可用于养殖水中孔雀石绿的含量测定。     

液相色谱串联质谱法测定养殖水体中孔雀石绿及其代谢物

研究利用液相色谱-串联质谱(LC-ESI-MS/MS)测定水产品养殖水体中孔雀石绿及其代谢物隐性孔雀石绿的方法.通过一系列实验对样品前处理条件进行了优化研究,养殖水样经乙酸酸化,净化后,采用HPLC-ESI-MS/MS检测分析.在多反应监测模式(MRM)下,外标法定量,定量限均为0.5μg/kg.在0.5～50μg/L...     

Rapid synthesis and characterization of ultra‐thin shell Au@SiO2 nanorods with tunable SPR for shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS)

The recently reported shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) is considered as the next generation of advanced spectroscopy for its surface and molecular generality. With the aim to utilize the virtues of shell‐isolated strategy and advance the SHINERS technique, we introduce a silane‐based rapid synthesis method of silica‐coating Au nanorods (Au@SiO₂ NRs) with manoeuvrable ultra‐thin shell and tunable SPR. The results demonstrate that the SPR of Au NRs could be optimized to obtain large Raman enhancement using either 633 nm or 785 nm laser. Differing from previously reported Au@SiO₂ NRs synthesis method, we can tune the silica shell thickness within several nanometers to maximize the Raman signal while effectively eliminating the exterior interference. And this advanced synthesis method has also significantly reduced the silica‐coating time from one day to ca. 1 h. This method as a new development of SHINERS technique has successfully got enhanced signal in solution Raman tests of malachite green, giving a great potential to be extended to in‐situ measurement for daily life detection. Copyright © 2013 John Wiley & Sons, Ltd.     

超高效液相色谱-串联质谱法测定水产品中孔雀石绿前处理方法的改进

采用超高效液相色谱-串联质谱法(UPLC-MS/MS)测定水产品中孔雀石绿的残留量,以GB/T 19857-2005检测方法为基础,将前处理步骤进行优化.称取5 g样品,加入质量浓度为100μg/L的内标标准溶液100μL,混匀,加入20 m L乙腈、5 g酸性氧化铝,震荡、离心,取4 m L溶液氮气吹干,用流动相定容至1 m L,过0.22μm滤膜,上机测试.按照标准方法测定标准曲线相关系数r:孔雀石绿为0.999,隐色孔雀石绿为0.999.孔雀石绿的回收率分别为71.7%、95.2%和89.9%,精密度分别为4.47%、4.26%和8.57%.隐色孔雀石绿的回收率分别为93.3%、98.8%和89.7%,精密度分别为8.73%、6.87%和9.71%.试验结果满足相关标准和体系文件的要求.