ICP－AES中内标法的应用研究 Ⅲ．用内标法校正基体干扰

通过观测基体对分析元素发射强度的干扰情况，分析干扰机制，从而确定用来校正基体干扰的内标元素与分析元素的匹配条件。实验结果表明，只要选择合适的内标元素，可以校正基体干扰。     

Thermodynamics of phenylated polyphenylene between 0 and 340 K

In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C _p of phenylated polyphenylene and initial comonomer 1,4-bis(2,4,5-triphenylcyclopentadienone-3-yl)benzene was studied between 6 and 340 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield their energies of combustion DUcomb were measured. From the experimental data, the thermodynamic functions C _p ⁰ (T), H ⁰(T)-H ⁰(0), S ⁰(T)-S⁰(0), G ⁰(T)-H ⁰(0) were calculated from 0 to 340 K, and standard enthalpies of combustion ΔH _comb ⁰ and thermodynamic parameters of formation-enthalpies ΔH _f ⁰, entropies ΔH _f ⁰, Gibbs functions ΔG _f ⁰ - of the substances studied were estimated at T=298.15 K at standard pressure. The results were used to calculate the thermodynamic characteristics (ΔH _f ⁰ ,ΔS _f ⁰, ΔG _f ⁰) of phenylated polyphenylene synthesis in the range from 0 to 340 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

The solubilization of alcohols in micellar solutions

The specific conductivities of dodecyldimethylbenzylammonium bromide (C12BBr) have been determined in aqueous butanol and aqueous benzyl alcohol solutions in the temperature range of 5-40°C. From these data the temperature dependent critical micelle concentration (cmc) was determined. The molar fraction of alcohol in the micelle was estimated using the theory suggested by Motomura et al. for surfactant binary mixtures. The thermal properties such as standard Gibbs free energy, enthalpy and entropy of solubilization of alcohols in the micelles were estimated for the phase separation model. The change in heat capacity upon solubilization of alcohol in the micelle has been estimated form the above properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermodynamics of hydrogen-isotope-exchange reactions. Proton solvation inn-hexanol and water

This paper reports our results for the direct experimental determination of the equilibrium constant for the hydrogen-isotope-exchange reaction, 1/2D₂(g)+HCl(hexOH)=1/2H₂(g)+DCl(hexOD), where hexOH isn-hexanol and hexOD isn-hexanol with deuterium substitution in the alcohol function. The reaction was studied in electrochemical double cells without liquid junction for which the net cell reaction is the above isotope-exchange reaction. The experimentally determined value of ε° (296.0°K) for this cell is 4.03±0.95 mV (strong electrolyte standard states, mole-fraction composition scale); the value of the equilibrium constant for the reaction is 1.17±0.05. The contributions of isotope-exchange and transfer effects to the magnitude of the standard Gibbs energy change for the above reaction and for the analogous reaction 1/2D₂(g)+HCl(aq)=DCl(daq)+1/2H₂(g) are considered. Our results support the conclusion of Heinzinger and Weston that the formulation of the solvated proton in water as H₃O⁺, as opposed to H₉O₄ ⁺, is sufficient for the interpretation of the thermodynamics of hydrogen-isotope-exchange reactions in water. We also find that the formulation of the solvated proton inn-hexanol as ROH ₂ ⁺ is sufficient for the interpretation of our results on the thermodynamics of hydrogen-isotope-exchange inn-hexanol.     

Calorimetric and thermal decomposition kinetic study of Tb(Tyr)(Gly)<Subscript>3</Subscript>Cl<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O

The solid-state ternary complex of terbium chloride with L-tyrosine and glycine, [Tb(Tyr)(Gly)₃Cl₃·3H₂O], was synthesized and characterized. Using a solution-reaction isoperibol calorimeter, the enthalpy of reaction for the following reaction, TbCl₃·6H₂O(s)+Tyr(s)+3Gly(s)=Tb(Tyr)(Gly)₃Cl₃·3H₂O(s)+3H₂O(l), was determined to be (5.1±0.6) kJ mol^-1. The standard enthalpy of formation of Tb(Tyr)(Gly)₃Cl₃-3H₂O at T=298.15 K has been derived as -(4267.3±2.3) kJ mol^-1. The thermal decomposition kinetics of the complex was studied by non-isothermal thermogravimetry in the temperature range of 325-675 K. Two main mass loss stages existed in the process of the decomposition of the complex, the kinetic parameters for the second stage were analyzed by means of differential and integral methods, respectively. Comparing the results of differential and integral methods, mechanism functions of the thermal decomposition reaction for its second stage were proposed. The kinetic equation can be expressed as: d/dt=Aexp(-E/RT)(1-)². The average values of the apparent activation energy E and pre-exponential factor A were 213.18 kJ mol^-1 and 2.51·10²⁰ s^-1, respectively.     

Standard enthalpy of formation of 3,4,5-trimethoxybenzoic acid

The energy of combustion of crystalline 3,4,5-trimethoxybenzoic acid in oxygen at T=298.15 K was determined to be -4795.9±1.3 kJ mol^-1 using combustion calorimetry. The derived standard molar enthalpies of formation of 3,4,5-trimethoxybenzoic acid in crystalline and gaseous states at T=298.15 K, Δ_fH_m ^Θ (cr) and Δ_fH_m ^Θ (g), were -852.9±1.9 and -721.7±2.0 kJ mol^-1, respectively. The reliability of the results obtained was commented upon and compared with literature values. This revised version was published online in August 2006 with corrections to the Cover Date.     

Some thermodynamic aspects of nitrides in materials science

The energies of combustion in fluorine of gallium nitride and indium nitride in wurzite crystalline structure have been measured in a two-compartment calorimetric bomb, and new standard molar enthalpies of formation have been calculated: Δ_fH_m⁰(GaN(cr) 298.15 K)= –(163.7±4.2) kJ mol^–1 and Δ_fH_m⁰(InN(cr) 298.15 K)= –(146.5±4.6) kJ mol^–1 . Comparison with the recommended values of the Δ_fH_m⁰ nitrides from the literature is also presented.     

Some aspects of quality assessment of the k0-based method of NAA

Neutron activation analysis is one of the analytical techniques often used for certification of reference materials. The k₀-based method of instrumental neutron activation analysis can also be applied in intercomparison runs in the certification process and therefore it is desirable to know its accuracy in advance. Possible systematic errors related to the application of nuclear data at given neutron flux rate parameters, that can affect the uncertainties of the results obtained by this specific method, are elucidated and error propagation factors calculated for a typical irradiation position in the TRIGA Mark II reactor of the Jozef Stefan Institute. It was found that these uncertainties are at the level of 1–2% on the average.     

指纹图谱法在参麦注射液质控中的应用

 中医药理论和实践要求综合评价中药的质量 ,指纹图谱法是对中药制剂进行综合宏观分析的可行手段之一 ,因此采用反相高效液相建立了参麦注射液的特征指纹图谱。条件 :Hypersil C18(4 6mmi d × 2 5 0mm ,5 μm)反相柱 ,流动相由水 (A)和乙腈 (B)组成 ,B的体积分数在 5 0min内由 5 %线性增长到 95 % ,流速为1 0mL/min ;紫外检测 ,波长为 2 0 2nm。 2 3个特征指纹峰与内标 (联苯 )的峰面积比作为指标 ,结合主成分分析 投影判别法比较了同一厂家不同批次产品和不同厂家同类产品的化学指纹差异。     

Blood lead monitoring in Italy: Assessment of the quality of results obtained between 1992 and 1994

Between 1992 and 1994, a new screening campaign for blood Pb monitoring in the Italian general population was carried out. Since the first campaign (started in 1978, in accomplishment of the European Community Directive 77/312/EEC) a working group of the Laboratory of Clinical Biochemistry at the Italian National Institute of Health (Istituto Superiore di Sanità), as the Reference Centre (RC), has coordinated the activity of various laboratories spread over the national territory. Appropriate quality assurance procedures, including an external quality assessment scheme (EQAS), were elaborated. Within the EQAS, three or four trials were carried out every year. Each laboratory participating in the trial analyzed eight control samples prepared from cow blood at different Pb concentrations. The results obtained by each peripheral laboratory and the RC between 1992 and 1994 have been compared by regression analysis. The same statistical method was adopted to compare the results obtained by each peripheral laboratory and the RC in the duplicate analysis of about 10 per cent of the human samples collected during the 1992–1994 monitoring campaign. There was no evidence of systematic differences between the regression lines obtained on control and human samples. In spite of the lower Pb concentration in the control samples analyzed during the 1992–1994 campaign, the analytical performance of the laboratories was better than that obtained in the previous screening campaign (1985–1986). Blood Pb levels observed in human samples collected between 1992 and 1994, confirm the downward time trend observed in the campaigns carried out in 1978–1979, 1980–1981 and 1985–1986. This study confirms that the results obtained in an EQAS are representative of the actual performance in the analysis of real (human) samples.