紫外分光光度法测定地下水中NO-3—N的含量

饮用水中NO-3-N的含量对人体有重要影响,因此测定地下水中NO-3-N的含量具有重要意义.本文用UA-1600紫外可见分光光度计,通过标准曲线法,在204nm波长处测定地下水中硝酸盐氮的含量.     

元素紫外—可见分光光度法分析方案设计系统初探

有关元素紫外－可见分光光度法分析方案设计系统及其知识库、推理机制的讨论表明,该系统设计的方案对元素的定量分析提供了显色体系、测量参数、消除干扰的方法等信息。对实际试样的检验表明该系统提供的方案是合理的。     

南蛇藤中9种金属元素含量的测定

采用原子吸收分光光度法，测定了南蛇藤中9种金属元素的含量．结果显示：南蛇藤中含有较丰富的钙镁、锰和铁等金属元素，其含量分别为6．720mg／g、2．410mg／g、0．5180mg／g和0．2281mg／g．     

稀硝酸溶液中微量砷的测定方法

目的为了确定测定稀HNO3溶液中低浓度的砷含量的简便方法,弥补国家标准砷含量测定方法的不足。方法利用HNO3和H2SO4分解温度的差异,将HNO3分解,再用分光光度计测定其中砷含量。结果经过实验确定在λ=515 nm时,稀HNO3中As含量与吸光度之间存在良好的线性关系:即mAs=39.06A-2.81,其中mAs单位为μg(mAs=1~13μg),线性相关系数r=0.9993,稀HNO3中As含量测定结果的相对标准偏差RSD为2.8%~3.5%,检出极限为0.5μg,平均回收率为96.3%。结论此方法可用于测定稀HNO3溶液中的微量砷,而且结果可靠,重现性好。     

青椒中还原型维生素C含量的测定

主要介绍了钼蓝比色法测定青椒中还原型维生素C含量的基本原理和方法。井对最大吸收波长和最佳显色条件进行了探究,实验结果是在波长839nm处有强吸收,维生素c含量在0．004-0．024mg／mL范围内呈线性关系,方法的变异系数小于2．51％,回收率为97．2％。该方法简单、快速、准确,用此法测得市售青椒样品中的还原型维生素c的含量为0．2390mg／g。     

Rapid reductive degradation of azo dyes by a unique structure of amorphous alloys

An Fe-based amorphous alloy was found to significantly enhance the reductive degradation of an azo dye in aqueous solution. The surface-area normalized rate constant was up to 2.0 L m-2 min-1 at room temperature,an order of magnitude larger than any previously reported value. The activation energy of the degradation process was calculated according to the Arrhenius equation,and a much lower value than those previously reported was obtained. Valence band measurement indicated that a depressed valence band maximum and a widened empty band were established in the amorphous ribbon. The unique structure of the amorphous alloy is important-it may reduce the activation energy of the degradation process and enhance the activity of the electrons,thus accelerating the degradation process.     

分光光度计示值不稳的故障分析和检修

本文对可见一紫外分光光度计在使用过程中出现的吸光度读数不稳的故障原因进行了分析,结合实例提出了排除这一故障的方法。     

紫外-可见分光光度法对去甲柔红霉素电离常数的研究

作者用紫外－可见分光光度法（UV－Vis）研究了抗癌药物－去甲柔红霉素的电离常数。配制了一系列pH值的去甲柔红霉素溶液并在去甲柔红霉素的特征波长485nm处分别测定它们的吸光度，根据吸光度的变化求得去甲柔红霉素的pHa值。该方法简单、易行，操作方便。     

Selective formation of tetrahedral Pt nanocrystals from K2PtCl6／PVP

Tetrahedral platinum (Pt) nanocrystals (3-8 nm) are synthesized in high selectivity (ca. 80%) from hydrogen reduction of aqueous K2PtCI6 by using polyvinylpyr-rolidone (PVP: Mw≈360000) as a protector. Morphology (TEM) measurements of the metal colloids and UV-Vis absorption of the colloidal solution are employed to monitor the tetrahedron formation during the syntheses with varying K2PtCl6/PVP ratios. The results clearly show a two-stage process for the selective formation of tetrahedral nanocrystals. Rapid nucleation and crystal formation at the early stage result in round-like crystallites and the external facet evolution in thereafter slow crystal growth leads selectively to the formation of the tetrahedrons.     

日立F-4500型荧光分光光度计的调试及应用

荧光法因其具有灵敏度高、选择性强、用样量少、方法简便等优点，现已广泛应用于食品检验、化学、医学、药物分析、冶金、生命科学和环境科学等各个领域。简单介绍了日立F-4500型荧光分光光度计的基本结构，对其波长扫描的调试方法做了详细介绍。