催化动力学光度法测定新鲜果蔬中痕量亚硝酸根

基于在稀磷酸介质中亚硝酸根对溴酸钾氧化百里酚蓝褪色反应的催化效应 ,建立了一种测定痕量亚硝酸根的催化光度法。该方法测定亚硝酸根的线性范围为 0～ 6 .5 μg/ 2 5ml,灵敏度为 0 .6 7ng·ml- 1。用于新鲜果蔬样品中痕量亚硝酸根的测定 ,结果满意     

偶氮胭脂红B光度法测定痕量铌

铌的测定常采用络合光度法,但络合光度法的灵敏度不高,一般在2~10μg/10 mL[1~4],难以达到痕量铌的分析要求,催化动力学光度法灵敏度高,目前以催化动力学光度法测定铌的报道较少,灵敏度能达到μg·L-1[5~7]。本文研究发现在硫酸中铌对溴酸钾氧化偶氮胭脂红B反应的影响作用,且铌量不同,其对反应的影响不同,据此在一定范围内建立了测定痕量铌的新方法。1试验部分1.1主要仪器与试剂723型分光光度计,CS501型超级恒温槽。铌标准溶液:100 mg·L-1,称取Nb2O50.143 0 g于瓷坩埚中,加焦硫酸钾5 g,缓慢加热熔融至清,冷却,用500 g·L-1柠檬酸溶液浸…     

新催化动力学光度法测定痕量亚硝酸根

在磷酸介质中,痕量亚硝酸根对溴酸钾氧化酰胺黑10B的催化褪色作用,建立了催化动力学光度法测定痕量亚硝酸根的新方法。并探讨了动力学反应条件,方法的线性范围为0.05～1.2μg/10ml,检出限为4.88×10-9·ml-1,用于地面水及雨水中亚硝酸根的测定,结果满意。     

催化荧光光度法测定痕量亚硝酸根

亚硝酸根广泛存在于环境、水体、食品等物质中，它可与胺类及酰胺类化合物反应生成致癌物亚硝胺，因此，它是水质、环境、食品等检测的重要项目之一。催化动力学光度法测定亚硝酸根已有不少报道，而催化荧光法测定亚硝酸根的报道不多。吡啰红B是一种生物染色剂，在水溶液中发射红色荧光。试验发现，稀磷酸介质中，溴酸钾氧化吡哕比B使荧光猝灭，亚硝酸根对此氧化还原褪色反应具有灵敏催化作用，据此建立了测定亚硝酸根的催化荧光光度法。本法灵敏度较高，选择性好，简便快速，用于水及蔬菜中痕量亚硝酸根的测定，结果满意。     

催化光度法测定痕量钒——钒（V）-溴甲酚紫-过氧化氢体系

催化光度法测定钒已有报道[1~3],在0.45 mol·L-1磷酸介质及加热条件下,过氧化氢氧化溴甲酚紫褪色反应非常缓慢,而痕量钒对此反应具有较高的催化活性,且在一定浓度范围内,钒量与褪色反应程度呈线性关系,据此可建立测定痕量钒的方法。方法的检出限为1.9×10-6g·L-1,测定范围为0·003~1.8 mg·L-1。方法操作简便,重现性好,用于钢样中痕量钒的测定,结果满意。1试验部分1.1仪器与试剂721型分光光度计LB801-2型超级恒温器钒(Ⅴ)标准溶液:1.000 0 g·L-1,称取偏钒酸铵0.229 7 g溶于热水中,冷却,定容于100 mL容量瓶中。溴甲酚紫(用R表示)溶液:…     

反相流动注射催化光度法测定亚硝酸根

采用反相流动注射技术与催化光度法相结合 ,研究了亚硝酸根在盐酸介质中催化溴酸钾氧化维多利亚蓝的灵敏褪色反应 ,用自制的微机化流动注射分析仪能准确控制时间 ,优化了试验条件 ,建立了测定痕量亚硝酸根的反相流动注射催化光度新方法。分析速度 36次·h- 1,克服了催化反应时间难以控制引起的方法精密度 ,准确度不高的弱点。亚硝酸根在 0 .0 0～ 2 .0 0mg·L- 1范围内 ,回归方程斜率为 0 .2 6 2。方法直接测定水中的亚硝酸根获得满意结果     

溴酸钾氧化酸性铬深蓝动力学光度法测定痕量亚硝酸根

亚硝酸根是环境中重要的污染物之一,是水质、环境、食品等检测的一个重要项目。催化动力学方法测定痕量亚硝酸根已有较多的报道^[1-6],但未见利用酸性铬深蓝指示物质的报道,酸性铬深蓝是一种配位滴定的指示剂。作者发现在稀疏酸介质中,亚硝酸根对溴酸钾氧化酸性铬深蓝褪色反应有灵敏的催化作用,并研究了该指示反应的动力学条件,建立了催化光度法测定亚硝酸根的新方法。该方法灵敏、简便,可用于水、蔬菜中亚硝根的测定。     

催化动力学光度法测定痕量亚硝酸根

研究了在磷酸介质中 ,亚硝酸根 (NO- 2 )对溴酸钾氧化二甲基黄催化作用的反应条件 ,建立了测定亚硝酸根的光度法。最大吸收波长在 5 15nm ,表观摩尔吸光系数为 3.0× 10 5L·mol- 1·cm- 1,方法的检出限为 9.16× 10 - 10 g·ml- 1,NO- 2 在 0～ 10 0ng·ml- 1范围内符合比耳定律。用于人唾液及洋葱中亚硝酸根的测定 ,结果满意     

溴酸钾氧化吖啶黄催化褪色光度法测定痕量亚硝酸根的研究

研究了在 0.10 mol·L-1的盐酸介质中,亚硝酸根催化溴酸钾氧化伯胺基结构碱性染料吖啶黄褪色反应的适宜条件与影响因素,建立了催化动力学褪色光度法测定痕量亚硝酸盐的新方法。亚硝酸根浓度在0.25~20.00μg/25 mL范围内符合比耳定律,其λmax=455nm,Sandell灵敏度为36.20 ng·cm-2,RSD为1.15%~5.97%,回收率为 97.5%~105.0%。方法用于环境样品、生物材料、食品等实际样品中亚硝酸根的测定,试剂简单,方法快速,选择性好,结果满意。     

催化光度法测定水中的痕量NO2-

基于磷酸介质中亚硝酸根催化溴酸钾氧化靛蓝胭脂红的褪色反应,建立了测定水中痕量亚硝酸根的催化光度法,并利用正交试验对测定方法进行了优化,亚硝酸根的检测限为1.36×10~(-6)g/L,线性范围为0.3～2.0 μg/25mL。该法用于蔬菜及环境水样中痕量亚硝酸根的测定,结果准确。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Effect of the Method of Modification of Zeolite X on Selectivity of Catalytic Methylation of Toluene

Theoretical and Experimental Chemistry - The effect of the method of modification of catalysts based on zeolite X by cesium and magnesium cations (ion exchange and impregnation) on the selectivity...     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of tetrabenzoporphins of the basis of isoindoline

Chemistry of Heterocyclic Compounds -