分光光度法中的试剂空白问题

在配合物的研究中,常用分光光度法测定配合物的含量.而所用的有机显色试剂往往具有颜色,试剂与有色配合物在测定波长时均产生吸收,通常采用相应的试剂空白作参比,以扣除试剂所产生的吸光度.然而试剂产生的吸光度值在反应开始和结束时是不相同的,因为在反应过程中,显色试剂要被消耗.反应结束后,过量试剂所产生的吸光度比反应开始时试剂的吸光度要小.这样,当反应达到平衡时,溶液总的吸光度值(A_(MR)+A_R)减去一个较大的试剂空白值,使测得的配合物的吸光度比真实值小.为此,需导出一个校正     

双波长分光光度法的研究进展

文中对双波长分光光度法在近十年来的研究进展作了评述。内容分为4部分：①常规双波长分光光度法；②标准加入法-双波长分光光度法；③计算双波长分光光度法及④双峰双波长分光光度法，引述文献23篇。     

分光光度法测定替米沙坦

用分光光度法研究了替米沙坦与茜素的荷移反应,提出了测定替米沙坦的荷移分光光度法。在丙酮溶剂中,替米沙坦和茜素形成的络合物的最大吸收波长为548nm,两者的组成比为1比2。替米沙坦质量浓度在16～240mg·L-1范围内服从比耳定律,表观摩尔吸光率为2.34×103L.mol-1.cm-1。采用此法分别测定了替米沙坦胶囊和片剂中替米沙坦的含量,所得测定值与文献报道值相符。用标准加入法做方法的精密度和回收试验,测得回收率为99.5%(胶囊)和99.8%(片剂)。     

紫外法与红外法测定石油类的比对研究

将新近实施用于测定地表水中石油类的紫外分光光度法与红外分光光度法的方法特性参数以及应用于各类实际水样测定进行比对研究。结果表明,两种方法的实际检出限均为0.004mg/L、测定下限均为0.016mg/L,加标回收样品紫外法测定结果相对标准偏差为4.2%～6.6%,加标回收率为82.0%～96.0%;红外法相对标准偏差为3.8%～5.5%,加标回收率为82.0%～97.0%,精密度和准确度等性能指标相近,在使用不同萃取方式应用于各种不同来源和组成水体的实际样品测定时,同种方法所得结果相对偏差均小于10%,但紫外分光光度法所得结果与红外分光光度法最大相对偏差达到了49.0%,并且红外分光光度法测定结果较之紫外分光光度法与样品理论浓度值更为接近,表明紫外分光光度法对较复杂水体石油类样品的测定存在局限性。     

辣椒素的分析方法比较

采用可见、紫外分光光度法和高效液相色谱法(HPLC)对辣椒不同部位的辣椒素含量进行了对照分析,同时用上述三种方法对色素、辣椒精及辣椒素晶体的辣椒素含量进行了对照分析。分析结果表明,HPLC方法与前两种方法相比,具有方法可靠、测得的结果准确度高等优点。     

2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚树脂相分光光度法测定污水中汞

树脂分光光度法属固相吸光光度法范畴,它对于痕量分析有很多优点,在该法中被测化学组分同时浓集和选择性吸附于树脂上,使分析手段简化,灵敏度和选择性均优于溶液中吸光光度法,故该法多用于环境污染物样品中痕量金属离子的定量测定.树脂相分光光度法基于直接测量吸附被测组分有色络合物树脂相的吸光度进行定量分析.本文研究了汞(Ⅱ)-与5-Br-PADAP反应生成络合物后富集于D152H型弱酸性阳离子交换树脂上于波长63Onm处测量吸附达平衡后的树脂相的吸光度,测定污水样品中痕量汞,结果满意,方便简便、快速、灵敏,选择性好.     

食物中微量元素硒的分析方法研究进展

就国内近年来对食物中微量元素硒的分析方法研究进展作一综述。包括：分光光度法，荧光光光度法、原子吸收分光光度法，电感耦合等离子体发射光谱法、极谱法、色谱法和中子活化法。     

茜素红与头孢哌酮的荷移反应研究与应用

实验以茜素红(ARS)为荷移试剂,采用分光光度法研究了ARS与头孢哌酮(CPZ)形成络合物的光谱性质及其反应的适宜条件.实验结果表明:头孢哌酮在2.0～200 μg/mL范围内遵循比尔定律,回归方程为:A=0.0036 p+0.000095(p:μg/ml),检出限0.75μg/mL,表观摩尔吸光系数2.64×10(4)L·mol-1·cm-1,相关系数为r=0.9965,并初步探讨了反应机理.用实验方法对尿样及生物样品进行加标回收测定,回收率在95.4%～104.8%.     

荷移分光光度法测定酒石酸美托洛尔

研究了酒石酸美托洛尔与紫色素之间的荷移反应。确定了反应条件,建立了一种测定酒石酸美托洛尔的荷移分光光度法。酒石酸美托洛尔与紫色素在乙醇介质中,室温条件下即可形成稳定的1∶1型荷移络合物,该络合物的最大吸收波长为540 nm,表观摩尔吸光率为6.83×103L.mol-1.cm-1。酒石酸美托洛尔质量浓度在10~80 mg/L范围内服从比耳定律,相关系数为0.9991。相对标准偏差为1.3%(n=11),回收率为99.3%~102.7%。     

某些分子光谱分析法测定核酸的进展

对近年来利用分光光度法、荧光法和共振光散射法定量测定核酸的现状进行了评述，表中列出了重要的反应体系及分析特征，引用文献77篇。     

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 -