高纯氧化铕中微量稀土杂质的化学光谱测定

将高纯Ｅｕ２Ｏ２通过Ｐ５０７萃淋树脂分离富集，分离掉大量基体Ｅｕ２Ｏ３剩下微量稀土杂质用碳粉吸附，加ＫＢＨ４作载体进行光谱测定，本方法可测定９９．９９９９％，纯度的Ｅｕ２Ｏ３中微量稀土杂质。     

Cluster approximation for covalent and ionic-covalent crystals

Suggested earlier technique of taking into account the boundary conditions for crystal structures with a significant constituent of a chemical bond has been realized basing on the method of high order finite differences. The consideration is carried out on the example of impurity substitution centers in GaAs (Si) and Si (P, S) crystals. Rather good agreement with the experimental results and the crystal approach has been achieved.     

用电感耦合等离子体质谱法测定高纯稀土中稀土杂质时的基体影响

考察了基体对待测稀土杂质元素信号的影响，研究了内标对基体效应的补偿作用。对于不同的基体元素最佳的内标元素是不一致的，Ｇａ、Ｉｎ、Ｉ、Ｃｓ和Ｔｌ是稀土纯度分析中合适的内标元素。内标法简便易行，效果好，其测定方法的精度和回收率令人满意。     

As-As dimerization, Fermi surfaces and the anomalous electrical transport properties of UAsSe and ThAsSe

A temperature dependent electron diffraction study has been carried out on UAsSe to search for evidence of As-As dimerization at low temperature. A highly structured characteristic diffuse intensity distribution, closely related to that recently reported for ThAsSe, has been observed at low temperature and interpreted in terms of a gradual charge density wave type phase transition upon lowering of temperature involving disordered As-As dimerization within (001) planes. Plausible models of the proposed As-As dimerization have been obtained using a group theoretical approach. Electronic band structure calculations of ThAsSe and UAsSe have been used to search for potential Fermi surface nesting wave-vectors. The results are in good agreement with the experimentally observed diffuse intensity distributions in both cases.     

The importance of impurity analysis in pharmaceutical products: an integrated approach

To purify a material and remove the excess impurities one should first recognize that whether they are actually present and what their nature is. In the past, this was not always done. But presently drug analysis and pharmaceutical impurities are the subjects of constant review in the public interest. The International Conference on Harmonisation (ICH) guidelines achieved a great deal in harmonizing the definitions of the impurities in new drug substances. It is necessary to perform all the investigations on appropriate reference standards of drug and impurities to get meaningful specifications. In order to meet the challenges to ensure high degree of purity of drug substances and drug products, a scheme is proposed for profiling drug impurity. Finally, analytical methods based on analytical instrumentation must be employed to quantitate drug substance and its impurities. Important aspects and suggestions related to drug analysis and pharmaceutical impurities are discussed.     

气相色谱-质谱法测定组合工艺己内酰胺产品中的微量关键杂质

己内酰胺（CPL）是重要的化工原料，CPL中即使存在微量的杂质都会对聚合产物的性能产生一定的影响，因此对聚合级CPL的纯度有很高的要求。该文对光密度值严重超标的组合工艺工业试验产品采用气相色谱-火焰离子化检测技术（GC/FID）、气相色谱-质谱（GC-MS）等手段进行了定性分析，确定该杂质的相对分子质量为188，分子式为C₁₂H₁₆N₂，环加双键数为6，为八氢吩嗪。结合组合工艺生产CPL所涉及化学反应的特点对八氢吩嗪的来源进行了理论推测，认为该杂质来源于Beckmann重排反应的副反应Neber重排，结构中含有较强的生色基团，对产品的光密度指标影响严重。因此，CPL生产过程中必须对八氢吩嗪的产生过程和生成浓度严格控制。     

铁、钠杂质对甲硫醚合成中γ-Al2O3催化行为的影响

系统地研究了γ－Al2O3催化剂中杂质Fe和Na对甲硫醚合成的催化行为的影响。随着Fe含量的增大，甲醇分解反应加剧，硫醇产率增高，甲硫醚产率下降；Na含量越低，甲醇分解率越高。Na含量在0．2％－0．4％时，甲硫醚产率最高，甲硫醇生成率最高；Na含量进一步增大时，甲醇双分子脱水生成甲硫醚的量增加，甲硫醇产率增高，生成甲硫醚的选择性下降。     

Structural and electronic properties of La‐doped CaTiO3 crystal

There is experimental and computational evidence that some important properties such as electrical conductivity and ferroelectricity in the CaTiO₃ crystal change according to the dopant states. Using an INDO quantum‐chemical computational method modified for crystal calculations we explore the stability of the La‐doped CaTiO₃ crystal in both phases, cubic and orthorhombic. The calculations are carried out by means of the supercell model based on the LUC (large unit cell) approach as it is implemented into the CLUSTERD computer code. The equilibrium geometry for impurity is found together with the crystalline lattice distortions. Atomic displacements and relaxation energies are analyzed in a comparative manner for the two crystallographic phases. A new effect of electron transfer from the local one‐electron energy level within the band‐gap to the conduction band is observed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Quantitation ofE. coli protein impurities in recombinant human interferon-γ

A multiple antigen ELISA for E. coli proteins (ECPs) that may be present in purified recombinant human interferon-gamma (rIFN-gamma) was developed. SDS-PAGE and Western blotting analyses showed that the assay antibodies reacted with a wide spectrum of ECPs in the standard and with ECPs in a production run. In spike recovery studies, rIFN-gamma at concentrations of 0.05 mg/mL and higher augmented the immunoreactivity of the ECPs in the standard curve (1.3-40.0 ng ECPs/mL) by approx 50%. To determine ECP content in purified rIFN-gamma, 0.2 mg/mL of rIFN-gamma was added to the standard curve diluent to compensate for enhanced immunoreactivity. The assay was precise (interassay precision of ECP controls < or = 4.1 %CV) and accurate with recoveries of 111-115% of expected for ECPs (15-40 ng/mL) spiked into purified rIFN-gamma (1 mg/mL). Linearity of dilution for ECPs spiked into rIFN-gamma was obtained (r = 0.999). Moreover, linearity of dilution was obtained for ECPs in "in-process" samples, demonstrating the required condition of antibody excess for this type of multiple antigen ELISA. ECPs were not detectable in several purified lots of rIFN-gamma. Therefore, these lots contained < 1.3 ppm ECPs.     

在线柱分离ICP-MS测定高纯Eu2O3中Tm

报道了一种在线柱分离ICP－MS快速测定高纯氧化铕中杂质铥的方法，采用一种新型膦酸类萃取剂，大大降低了林洗酸度，洗脱液中的Tm直接进入ICP－MS进行在线测定。整个分离测定周期为40min，方法检出限为0．12ng/mL，加示加收率为91．5％－98％，RSD为4．1％，该方法快速，简便。用于高纯氧化铕中杂质铥的测定，结果满意。