Multicomponent analysis with a computerized flow injection system using LED photometric detection

An original computer-controlled solid-state photometer has been developed and its potential for simultaneous multicomponent flow-injection analysis of binary and ternary mixtures is demonstrated. The device is simple in construction. Its principle of operation is based on rapid sequential measurements of the absorbance of the complexes formed by the analytes with chromogenic reagents at the wavelengths corresponding to the emission maxima of three light emitting diodes (563, 580 and 638 nm).     

Preparation and partial characterization of a soluble site-to-site directed enzyme complex composed of alcohol dehydrogenase and lactate dehydrogenase

A soluble, bifunctional enzyme complex has been prepared by crosslinking lactate dehydrogenase and alcohol dehydrogenase with glutaraldehyde. The crosslinking was performed on a solid phase while the active sites of alcohol dehydrogenase and lactate dehydrogenase were held adjacent to one another with the aid of a bis-NAD analog. Subsequently, the enzyme complex was released from the solid phase. The soluble enzyme complex was then purified by using NAD-Sepharose as an affinity adsorbent. Based on gel filtration experiments, the complex was estimated to consist of one of each dehydrogenase. By using a third enzyme, lipoamide dehydrogenase, which competes with lactate dehydrogenase for NADH produced by alcohol dehydrogenase, the effect of site-to-site orientation was studied. It was found that about 83% of the NADH produced by alcohol dehydrogenase was oxidized by site-to-site oriented lactate dehydrogenase compared to a figure of only about 61% obtained in an identical system of separate enzymes. This indicates that given two alternative routes, the preference for the one to lactate dehydrogenase over the one to lipoamide dehydrogenase is enhanced when lactate dehydrogenase and alcohol dehydrogenase are site-to-site oriented.     

Mass Spectra of N-Arylglycines and Substituted Aniline-N,N-Diacetic Acids

The electron impact mass spectra of eleven N-arylglycines and seven substituted aniline-N,N-diacetic acids were obtained under 70 eV and 14 eV ionization energies. The fragmentation patterns are similar to those of α-amino acids except for the degree of cleavage. The dehydration process of the diacetic acids may be considered as the characterestic process for this group of compounds.     

PAN共沉淀富集原子吸收测定饮水和人发中的微量锰

使用PAN-Ni(Ⅱ)共沉淀体系分离富集、微量流向进样火焰原子吸收光谱测定饮水和人发中的微量锰。样品中的共存元素不干扰测定，锰的标准加入回收率90%-108%之间。12次重复测定锰含量为0.15μg/mL的试样溶液的变异系数为4.6%,本法简便快捷,取得了较满意的结果.     

5-Acyl-4-amino-2-phenyl-1,3-oxazin-6-ones

Intramolecular cyclization of acyl(ethoxycarbonyl)keteneN-benzoylaminals in boiling Ph₂O gives 5-acyl-4-amino-2-phenyl-1,3-oxazin-6-ones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1322–1323, July, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08964).     

Surface modification of proteins by covalent binding of acrylic polymers

Surface modification of enzymes for a potential use in therapy was obtained with a new type of tailor-made copolymers ofNacryloylmorpholine andN-acryloxysuccinimide. The first monomer was designed to confer solubility on the polymer, whereas the second was used to give it reactivity toward protein amino groups. The reactivity of polymers of different composition towards amino acid derivatives and model proteins, such as catalase and ribonuclease-A, is described. Water soluble and catalytically active enzyme derivatives were obained using copolymers prepared with a mixture of N-acryloxysuccinimide andn-acryloylmorpholine in a 1:99 molar ratio. At increasing molar ratio (3:97, 10:90) extensive crosslinking between polymer and enzymes takes place, yielding insoluble adducts.     

Chiroptical detection. Novel possibilities of its application to enantiomers

Summary Polarimetric and/or circular dichroic detection of enantiomers after liquid chromatography on optically active sorberts has been used for the following purposes: determination of enantiomeric purity in spite of peak overlap, investigation of enantiomerization during chromatography, monitoring of racemizations and recording of circular dichrograms without preparative enrichment of enantiomers. Novel examples for all applications are give. The general prospects for chiroptical detection are discussed.     

中药一枝黄花、黄连、天麻、蛇床子中8种微量元素的测定

采用原子吸收光谱仪对一枝黄花、黄连、天麻、蛇床子中Fe、Ca、Mg、Mn、Cr、Cu、Zn、Pb八种无机元素的含量进行了测定,为进一步研究其药理和用途提供基础。     

液体色谱,凝胶色谱分析低聚芳砜及其双烯大分子单体

本文用液相色谱和凝胶色谱对双酚A、双酚S型低聚芳砜及α,ω-双甲基丙烯酸聚芳砜酯大分子单体进行了组分分析,通过改合成条件、测定数均分子量等辅助手段确定液相色谱各峰的归属,计算其分子量及分子量分布指数,并对两种方法测定的结果进行了比较。用液相色谱观察低聚体每个组分的含量及其反应过程中的消长情况比凝胶色谱清晰。