阻抑催化动力学光度法测定痕量二苯胺

二苯胺是一种易挥发的毒性化工原料,空气中最高允许浓度为10 mg·m-3[1].测定二苯胺的方法主要有荧光法[2],气相色谱法[3,4],气相色谱-质谱法[5],间接光度法[6]等.     

气相色谱-邻苯二甲酸二甲酯内标法同时测定硝基苯酚的三种异构体

酚类已被列为优先控制的环境污染物,属高毒物质,其中硝基苯酚的3种异构体的分析测定备受关注。目前,已有采用分光光度法[1]、离子色谱法[2]、高效液相色谱法[3]测定的报道,但未查阅到采用气相色谱法对硝基苯酚的3种异构体同时分离和测定的系统研究。本文采用乙酸酐衍生化法对3种酚进行衍生,使之成为酯类进行分离[4],并采用邻苯二甲酸二甲酯作为内标物进行定量分析。1　实验部分1.1　主要仪器与试剂　　美国Agilent6890气相色谱仪,氢火焰离子化检测器(FID),HPRev.A.08.01化学工作站;HP 5毛细管柱。邻、间、对硝基苯酚及乙酸酐、甲苯…     

阻抑动力学荧光法测定痕量苯胺

苯胺及其衍生物有剧毒且是致癌性物质。环境中苯胺的含量已成为各国环保、卫生部门重要的检测指标之一。测定苯胺的方法有色谱法、电化学法、分光光度法及荧光法等。动力学分析法灵敏度高、简便快速,已经有测定苯胺的报道,但动力学荧光法测定苯胺的报道极少。有人基于苯胺对溴酸钾氧化荧光素的抑制作用,建立了抑制—褪色分光光度     

紫外分光光度法测定蔗糖含量

有关蔗糖含量的测定法有很多,如旋光法、气相色谱法、液相色谱法、分光光度法等。旋光法测量准确性较差;气相色谱法和液相色谱法测量过程较复杂;文献报道的分光光度法,是在蔗糖的溶液中加入显色剂间苯二酚或2,4,6-三硝基酚,反应生成有色物质,并测其吸光度,文献报道的分光光度法,用酶水解蔗糖,加入4-氨替吡啉苯酚显色,再测吸光度。     

红茶中茶黄素类物质的高效液相色谱分离及其定量测定

红茶中茶黄素类[Theaflavins]物质的含量对茶叶的品质和市场价格影响很大。茶叶中茶黄素类物质含量的测定,最常用的方法是溶剂萃取—分光光度法测定其总量,后来逐步发展了纸色谱法和经典柱色谱法,也有人采用气相色谱法进行测定,但样品需经过复杂的预处理和衍生化处理Hoefler和Coggon首先将高效液相色谱用于茶黄素的分离,但定量工作未见报道。     

气相色谱法快速测定食品中山梨酸和苯甲酸

苯甲酸、山梨酸作为食品添加剂广泛应用于食品、饮料等。其使用限量各国对于不同的食品有不同的要求。有关食品中苯甲酸、山梨酸的测定方法报道较多,有分光光度法、液相色谱法、薄层色谱法及气相色谱法。由于气相色谱法较为普及且应用较为方便,通常都采用气相色谱法进行日常分析。我们在应     

梯度洗脱色谱法同时测定康糖片中盐酸小檗咸、黄芩苷、格列本脲的含量

康糖片是治疗糖尿病的中西药复方制剂,主要由盐酸小檗碱、黄芩苷、格列本脲等组成.其中的单组分含量测定方法报道较多,如盐酸小檗碱有分光光度法[1]、薄层色谱法[2]、高效液相色谱法[3]等;黄芩苷有比色法[4]、薄层色谱法[5];格列本脲有高效液相色谱法[6].但同时测定上述3种组分的方法未见报道.本文报道了同时测定上述3种组分的高效液相色谱方法,方法简单、灵敏、回收率高、专属性强,能有效地控制药品的主成分含量,具有较强的实用价值.     

水体中硝基芳烃类有机污染物分析方法研究进展

硝基芳烃类有机物是一类重要的化工原料,也是性质相对稳定、难以降解的高毒污染物。其检测技术主要有分光光度法、电化学法、液相色谱法、气相色谱-电子捕获检测器法(GC/ECD)、气相色谱-质谱法(GC-MS)等。其中GC/ECD法和GC-MS法因测定准确、灵敏、适用范围广而得到广泛应用。该文从不同类型水体中硝基芳烃类有机物样品的采集、前处理以及检测分析技术的选择角度,对硝基芳烃类有机物检测技术的发展进行了简要评述,同时对其分析方法进行了展望。     

流动注射不可逆双安培法测定对乙酰氨基酚

对乙酰氨基酚(ACOP,扑热息痛)是一种常见的解热镇痛药,其含量测定对于研究药物的药理作用、临床疗效、合理用药、开发资源、质量控制等具有重要意义。目前的测定方法主要是国家药品标准中的紫外分光光度法[1]以及重氮化法[2],高效液相色谱法(HPLC)[3],气相色谱法(GC)[4],毛细管     

正交函数吸光光度法测定食品中山梨酸

食品中常用的添加剂有色素、苯甲酸、山梨酸、糖精钠等,其中苯甲酸、山梨酸、糖精钠常用乙醚提取后测定,但不能互相分离,因此国家卫生标准分析方法采用薄层色谱法、气相色谱法[1],这些均属分离分析方法,也有导数光谱分析方法[2,3]。采用正交函数吸光光度法测定,可有效地消除共存的苯甲酸、糖精钠等的干扰,这种测定方法可以在普通的紫外 可见分光光度计中进行测定,不需要价格昂贵的高档分光光度计,因而具有推广价值。正交函数分光光度计是通过适当的数学处理,对测试波长区间与间隔、测试点数目以及正交多项式次数作合理的选择,求得正交多…     

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。     

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...     

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.     

Synthesis of tetrabenzoporphins of the basis of isoindoline

Chemistry of Heterocyclic Compounds -