酶抑制技术检测蔬果农药残留量研究进展

综述了国内外近年来酶抑制技术在农药残留检测中的应用研究状况，重点论述了酶抑制光度法的优点及存在的问题以及酶的固定化的应用研究，检测有机磷与氨基甲酸酯农药的酶电极的制备与应用是研究的热点．     

酶抑制法农药残留快速测定仪灵敏度的校准

用农药残留测定仪在波长412 nm处测定农药吸光度的变化值,根据酶抑制法计算抑制率,抑制率与农药浓度呈正相关。用农药标准物质从低于规定的农药检测下限开始配制一系列标准溶液对仪器进行校准,在抑制率为50%处的浓度即为仪器的灵敏度。对影响校准结果的因素进行分析,该方法校准结果的相对扩展不确定度为4%。     

以十二烷基硫酸钠为增敏剂催化光度法测定痕量锰

报道了以阴离子表面活性剂十二烷基硫酸钠(SDS)为增敏剂,高碘酸钾氧化茜素绿催化之度法测定衣量锰的方法。方法中添加了阴离子表面活性剂SDS,灵敏度提高4．3涪(锰含量0-0．6ns·ml-1)和5．7倍(锰含量0．6-1．6ng·ml-1),相对标准偏差为2．6%(n=11),检出限为4．06×10-11g·ml-1。     

双氧水活化-面粉酶抑制法测定蔬菜中有机磷农药

基于α-乙酸萘酯和固蓝B在面粉酶的催化作用下生成紫红色的偶氮化合物,而有机磷农药在双氧水的活化下会抑制酶的催化作用,其抑制程度与农药的浓度在一定范围内呈线性关系,由此建立了一种快速测定有机磷农药的方法。探讨了最佳的反应条件,测定甲基对硫磷和甲胺磷的线性范围分别为1~10μg/mL,1~50μg/mL,最低检出限分别为0.1136μg/mL,0.3525μg/mL。该法具有试剂廉价易得、操作简便、迅速的特点,适合果蔬中常见有机磷农药的快速检测。     

光度法快速测定土壤中呋喃丹

呋喃丹是一种内吸性杀虫剂。因其残留毒性高,口服易急性中毒,是蔬菜生产过程是禁用的农药。但个别错误施用的现象时有发生,给土壤和蔬菜带来了污染。因此,研究呋喃丹在土壤中残留的分析方法具有重要意义。呋喃丹属氨基甲酸酯类农药,可用农药残留快速测定法(酶抑制法)测定,但检出限高且不能准确定量测定。国家标准采用色谱法测定,但样品处理和仪器要求高,不能用于快速检测。     

用于农药残留检测的酶生物传感器

酶生物传感器在农药残留检测方面具有传统检测方法不可比拟的优势.本文介绍了胆碱酯酶和有机磷水解酶在生物传感器中的应用,重点介绍了用于有机磷等农药残留分析的酶生物传感器的种类和研究现状,讨论了几种酶固定化方法存在的优势和局限,指出了目前研究需解决的问题并展望了未来的发展方向.     

气相色谱法测定反季节蔬菜中农药残留

采用气相色谱法测定反季节蔬菜豇豆和苦瓜中毒死蜱、除尽、联苯菊酯、功夫菊酯和氯氰菊酯等5种农药残留量。样品经乙腈提取后,所得豇豆提取液经0.22μm滤膜过滤,所得苦瓜提取液经Agela Cleanert PestiCarb-SPE固相萃取柱净化。在DB-1毛细管色谱柱上,5种农药达到很好分离。5种农药的线性范围均为0.01～5.0mg·L-1。方法用于测定豇豆和苦瓜中5种农药的残留量,并在2个不同浓度水平下进行了回收和精密度试验,所得回收率在64.7%～98.8%之间,相对标准偏差(n=6)小于9.0%。     

电动流动分析和酶抑制法测定池塘水中农药残留折合总量

用电动流动分析和酶抑制法测定池塘水中有机磷和氨基甲酸酯农药残留折合总量。电动流动分析系统由一台自制电渗泵和4个电磁切换阀组成,由计算机编程控制。酶抑制法用面粉酯酶,有机磷和氨基甲酸酯农药作酶抑制剂,底物的酶解产物与显色剂反应,用分光光度计在524 nm检测。有机磷和氨基甲酸酯农药的折合浓度对数线性范围为0.02~0.20 mg/L乐果,检出限为0.01 mg/L乐果,每小时可测24个样品。氨基甲酸酯在80℃完全水解,而有机磷部分水解,据此可判断农药类别。     

农药残留快速检测中酶催化动力学分析的算法改进

本文对现有的农药残留快速检测中酶催化动力学分析法的算法进行了改进,以多点采样最小二乘法代替简单的两点法计算斜率,以光强值代替吸光度值来测量斜率。这些改进简化了计算,提高了分析结果的准确度,并在本研究所开发的便携式农残检测仪上得到了应用。     

酶免疫分析技术在农药残留分析中的应用

介绍了水、土壤和食品中农药残留的酶免疫分析技术的原理、类型及方法的开发与应用。引用文献22篇。     

Mixing Behavior of Cationic Hydrotropes with Anionic Surfactant Sodium Dodecyl Sulfate

Mixing behavior of anionic surfactant sodium dodecyl sulfate (SDS) with cationic hydrotropes aniline hydrochloride (AH), o-toluidine hydrochloride (o-TH), and p-toluidine hydrochloride (p-TH) have been studied using conductivity at different temperatures. Critical micelle concentration for different mixing mole fractions, their ideal values, and different interaction parameters have been estimated. All the parameters show nonideal behavior with synergistic interactions. Thermodynamic parameters are also calculated for these systems.     

十二烷基磺酸钠对大豆过氧化物酶活性和构象的影响

在不同的pH值体系中, 利用酶活测量、圆二色谱、荧光谱和电子吸收谱研究了十二烷基磺酸钠(SDS)对大豆过氧化物酶(SBP)活性与构象的影响情况. 在pH 2.6和4.2 的体系中, 少量的SDS分子可通过静电作用与SBP结合, 进而与SBP分子中的His169残基结合, 降低其与铁卟啉的配位能力, 使其Soret吸收带蓝移, 二级结构发生轻微的变动, 活性永久丧失. 在pH 5.2体系中, SDS和SBP分子都带负电, 由于静电排斥作用, SDS无法进入SBP的分子内部, 失去与SBP分子中His169残基结合的能力, 对SBP分子的二级结构没有影响, 仅对SBP分子的三级结构有所影响. 当SDS的浓度大于临界胶束浓度时, 由于胶束与SBP的静电排斥作用增强, 限制了铁卟啉中乙烯基的运动, 乙烯基与卟啉环的共轭程度增大, Soret 吸收带红移. 由于SBP活性可完全恢复, 此变化是可逆的.     

Precipitating Sodium Dodecyl Sulfate to Create Ultrastable and Stimulable Foams

Ultrastable foams are made very simply by adding salt (NaCl or KCl) to sodium dodecyl sulfate. The addition of high concentrations of salt leads to the precipitation of the surfactant on the bubble surfaces and as crystals in the interstices between the bubbles. As a consequence, the ageing of the foams is stopped to make them stable indefinitely, or until they are heated above the melting temperature of the crystals. The use of KCl is shown to be much more effective than that of NaCl because potassium dodecyl sulfate has a higher melting temperature and faster rates of crystallization. The crystalline structures have been investigated inside the foam using small angle neutron scattering. The larger lattice spacing of the crystals formed with NaCl in comparison with KCl has been evidenced. These simple temperature stimulable foams could have many potential applications.     

Atomic Absorption Spectrophotometry of Chromium Using an Enhancing Effect of Sodium Dodecyl Sulfate

Abstract

In the atomic absorption spectrophotometry of chromium with the air-acetylene flame, the absorption of chromium was increased by about 120% in the presence of sodium dodecyl sulfate (SDS) above the critical micelle concentration (CMC). This phenomenon was applied to overcoming interferences from many coexisting cations and some acids.     

The Electrooxidation of Tetracycline at Acetylene Black Electrode in the Presence of Sodium Dodecyl Sulfate

The electrooxidation of tetracycline (TC) at acetylene black electrode has been studied in the presence of sodium dodecyl sulfate (SDS). Tetracycline (TC) exhibited very sensitive oxidation peak in this system. The peak current was proportional to TC concentration, and the detection limit was 1.2×10-8 mol/L. The system was used to the determination of TC in Pharmaceuticals.     

十二烷基硫酸钠增敏荧光光谱法测定盐酸小檗碱

基于十二烷基硫酸钠(SDS)对盐酸小檗碱荧光有显著增敏作用,建立了测定盐酸小檗碱的荧光光谱法。在pH 7.0的Tris-HCl缓冲溶液中,盐酸小檗碱与0.01mol·L-1的SDS溶液反应15min后,体系在530nm处的荧光强度达到最大。盐酸小檗碱的浓度在1.0~10mg·L-1范围内与体系荧光强度呈线性关系,检出限(3s/k)为0.23mg·L-1。方法应用于制剂中盐酸小檗碱含量的测定,结果与药典法测定结果一致。加标回收率在94.9%~106%之间,测定值的相对标准偏差(n=6)在1.9%~3.7%之间。     

L-半胱氨酸在SDS吸附胶束中的电化学催化氧化

The electrochemical oxidation of L-cysteine can be catalyzed by sodium dodecyl sulfate (SDS) admicelles. The catalytic efficiency increases hardly when SDS concentration is lower than the critical admicelle concentration (CAC) and increases rapidly when SDS concentration is between CAC and the critical micelle concentration (CMC), but decreases when SDS concentration is higher than CMC. Both results of rate constant k^0 and Gibbs free energy ΔG^ck accord with that of catalytic efficiency.