Study on a New Method of Extraction of Metal Ions from Solid Matrices by Supercritical Fluid

TOdate.mostofthepublishedSFEworkshavefocusedonorganiccompound',andsomereportshaverelatedtoSFEofmetalions2.DirectextractionofmetalionsbysupercriticalCO,ishighlyinefficient.OneapproachofextractingmetalionsbysupercriticalCO=issuggestedtoconvertthechargedmetalionsintoneutralmetalcomplexesbyusingchelatingagentinthesupercriticalCO,.Avarietyoforganicchelatingagentssuchasthiocarbamate,D-diketones,andcrownetherhavebeenusedinSFEofmetalions3.8Hydroxyquinolinecontainsdoublecoordinationatoms(N,O-),…     

改性剂Sb对BaTiO3基PTCR陶瓷电学性能的影响

以溶胶－凝胶一步法合成了含有改性剂Sb的BaTiO3基正温度系数电阻（positive temperature coefficient of resistivity,PTCR)陶瓷,着重讨论了改性剂Sb掺杂量的变化对PTCR陶瓷电学性能的影响。结果表明,随改性剂含量的增加,材料的室温电阻率（ρ室）、电阻－温度系数（α）、耐电压强度（VB.max)均呈现“W”形变化。     

毛细管区带电泳法快速分离硝基酚和除草剂

 运用毛细管区带电泳法 ,通过在缓冲溶液中添加多阳离子化合物改变电渗流方向的方法 ,快速分离了 11种一取代、二取代和三取代硝基酚及 4种在德国常用的除草剂Bromoxynil,DNOC ,Dinoterb和Ioxynil。使用UV检测 ,这些化合物的检测限在 0 5mg/L～ 1 1mg/L。为满足环境样品分析的要求 ,使用固相萃取方法对样品进行了预处理 ,使硝基酚的检测限达到 1μg/L以下 ,并对实际样品进行了分析。     

MBS对PVC的改性机理

MBS改性剂是甲基丙烯酸甲酯MMA－丁二烯PB－苯乙烯St的共聚作。作为透明PVC的改性剂,它的化学组成、粒径尺寸以及粒子结构等诸多因素都影响到了PVC／MBS合金的力学和光学性能。文中在分析MBS改性机理的基础上,合成出化学组成25／60／42,粒径约为0．3μm的核－壳结构型MBS改性剂,测定PVC／MBS的合金的综合性能,均得到很好的数据。     

Determination of trace iron in high purity sodium fluoride by graphite furnace atomic absorption spectrometry

A method is described for the direct determination of iron in high purity sodium fluoride using graphite furnace atomic absorption spectrometry. Interferences caused by the matrix are investigated. It is shown that the ashing temperature can be increased to 1 400°C and matrix interferences eliminated, the sensitivity of iron increased in 1. 27 fold by the addition of nickel nitrate. The method is applied to the determination of iron in sodium fluoride and satisfactory results are obtained. Biography: QIAN Sha-hua (1954-), female, associate professor     

Study of some palladium-containing chemical modifiers in graphite furnace atomic absorption spectrometry

Several chemical modifiers based on palladium have been evaluated: the individual Pd(II) and the mixed modifiers Pd + Zr, Pd + W, Pd + Zr + citric acid, Pd + W + citric acid. The mechanisms by which these chemical modifiers stabilize analytes and control atomization have been suggested. Factors that might have an influence on the characteristic mass and non-spectral interferences are discussed. The advantages and limitations of the palladium-tungsten modifiers are shown.     

L-45脲醛树脂胶粘剂的研制

L-45脲醛树脂胶粘剂是在普通脲醛树脂胶合成方法的基础上,采用一次加料、不脱水工艺,以1.3%左右的三聚氰胺和4%左右的聚乙烯醇为改性剂的改性胶。它的耐沸水性与普通胶相比有显著提高,一般剪切强度也有所提高,游离甲醛含量也下降很多。此种改性胶的耐水强度达到国家Ⅰ类胶合板所用胶粘剂的标准。     

基于模糊修正的叉车自动称重系统研究

针对叉车的工作特点,探讨了叉车自动称重系统的设计方法,分析了叉车的受力情况,对系统的组成、信号采集、数据处理进行了研究.重点阐述了二维测力和模糊修正的组合新方法,实现了称重的智能化,保证了受载信号的精确度,同时论述了称重时货物的偏载影响及消除这些影响的措施,实验证明了本系统的有效性.     

Band broadening arising from stepwise alterations in mobile phase composition in micellar electrokinetic chromatography

Summary Gradient elution in micellar electrokinetic chromatography has been proposed as a technique for extending the elution range and adjusting retention factors for optimum values. It is shown that this approach in practice has not only to be evaluated for adjustment of retention factors but also for the reduced efficiency of the chromatographic system arising from alterations in the separation buffer during the run. Stepwise gradient elution, feasible with commercial instrumentation, results in marked peak broadening attributable to effects of the border zone passing the solute zone.