各种氨基酸衍生物在Chirasil—Val固定相上的气相色谱分离

本文叙述氨基酸及其对映体的全氟酰基烷基脂(O-异丙基、-异丁基、-正丁基;N(O,S)-三氟乙酰基,TFA、-七氟丁酰基,HFB)在Chirasil-Val上的洗脱特性。随烷基取代增大,保留时间增加;用HFB代替TFA,对映体的分离因子降低。此外,DL-氨基酸与另丁醇衍生,生成的对映及非对映衍生物在Chirasil-Val上可拆分成四个色谱峰。     

气相色谱法测定饮料中乙醇含量

采用样品用注射器吸附后直接经C18柱后进样，用气相色谱法测定，该方法适合多样饮料中的乙醇测定，平均回收率为98．6％，检出限为7．7mg/L。     

人尿中诺龙和炔诺酮代谢物的气相色谱-质谱分析

本文对合成的19-去甲雄烷醇酮的四个差向异构体混合物进行气相色谱分离,对诺龙和炔诺酮用药后,留取的人尿样通过化学预处理,MSTFA/TMSI衍生化反应,GC/MS分析,确证了尿样中诺龙的两个主要代谢产物为19-去甲雄酮和19-去甲原胆烷醇酮,炔诺酮的两个主要代谢物是四氢炔诺酮(THINE)的两个形式,可能是3α-OH-5α-THINE和3α-OH-5β-THINE,在炔诺酮代谢前期,还发现有诺龙的上述两个代谢物存在。     

Dynamic percolation transition induced by phase separation: A Monte Carlo analysis

The percolation transition of geometric clusters in the three-dimensional, simple cubic, nearest neighbor Ising lattice gas model is investigated in the temperature and concentration region inside the coexistence curve. We consider quenching experiments, where the system starts from an initially completely random configuration (corresponding to equilibrium at infinite temperature), letting the system evolve at the considered temperature according to the Kawasaki spinexchange dynamics. Analyzing the distributionn _l(t) of clusters of sizel at timet, we find that after a time of the order of about 100 Monte Carlo steps per site a percolation transition occurs at a concentration distinctly lower than the percolation concentration of the initial random state. This dynamic percolation transition is analyzed with finite-size scaling methods. While at zero temperature, where the system settles down at a frozen-in cluster distribution and further phase separation stops, the critical exponents associated with this percolation transition are consistent with the universality class of random percolation, the critical behavior of the transient time-dependent percolation occurring at nonzero temperature possibly belongs to a different, new universality class.     

Spin interaction with an ideal Fermi gas

We consider the equilibrium dynamics of a system consisting of a spin interacting with an ideal Fermi gas on the lattice , 3. We present two examples: when this system is unitarily equivalent to an ideal Fermi gas or to a spin in an ideal Fermi gas without interaction between them.     

L—氨基酸氧化酶电极的制作及电极特性的研究

报道了一种新的Ｌ－氨基酸氧化酶电极，这种酶电极系由氨气敏电极和以氨基化玻璃布为载体的酶膜所组成；研究了固定化条件对酶膜活性的影响以及底物浓度、温度和ｐＨ对电极响应特性的影响。该电极在６．０×１０＾－５～４．０×１０＾－３ｍｏｌ／Ｌ的底物浓度范围内呈良好的线性关系，检测下限为５．０×１０＾－５ｍｏｌ／Ｌ。在最宜条件下，酶电极具有良好的稳定性。     

Thermal decomposition of Cd(CH3COO)2·2H2O studied by a coupled TG-DTA-MS method

The thermal decomposition of cadmium acetate dihydrate in helium and in air atmosphere has been investigated by means of a coupled TG-DTA-MS method combined with X-ray diffraction analysis. Dehydration of Cd(CH₃COO)₂·2H₂O is a two-stage process with Cd(CH₃COO)₂·H₂O as intermediate. The way of Cd(CH₃COO)₂ decomposition strongly depends on the surrounding gas atmosphere and the rate of heating. CdO, acetone and CO₂ are the primary products of decomposition in air. In helium decomposition goes by two parallel and consecutive reactions in which intermediates, Cd and CdCO₃, are formed. Metallic cadmium oxidizes and cadmium carbonate decomposes giving CdO. Some of the metallic cadmium, depending on the heating rate and the concentration of oxygen, evaporates. Acetone is partially oxidized in secondary reactions with oxygen. This revised version was published online in July 2006 with corrections to the Cover Date.     

气相-质谱法测定粮谷中恶草酮的残留量

 应用微量化学法和固相萃取技术 ,建立了粮谷中恶草酮残留量的气相 质谱 (GC MS)测定方法。用苯 正己烷 (体积比为 1∶1)萃取 ,中性氧化铝小柱净化。净化液用GC MS测定 ,采用外标法定量。恶草酮在大米中的回收率为 90 4%～ 115 .7% ,RSD为 2 %～ 6 % ,在玉米中的回收率为 81 3%～ 10 9 7% ,RSD为 4%～ 9% ,最低定量检出限为 0 0 0 5mg/kg。该法快速、灵敏、准确 ,各项技术指标均满足农药残留检测的要求。     

Dynamic headspace analysis of trace volatile components in polymeric materials by wide bore capillary gas chromatography

A novel dynamic headspace gas chromatographic system equipped with a wide bore capillary column was constructed for direct analysis of less volatile components in polymeric materials such as coating paints. With this system, the determination of typical paint additives such as hindered amine light stabilizers and ultraviolet absorbers could be carried out within a short time.     

Reaction gas chromatography: Study of the photodecomposition of selected substances

Summary A simple apparatus that permits to carry out photolytic reactions in direct connection with a gas chromatograph has been designed. The photodecomposition of C₅–C₇ aliphatic alkanes, C₁–C₅ primary, secondary and tertiary aliphatic alcohols and of some other substances was studied using this apparatus. The degradation products are characteristic of the individual types of alcohols. The identification of the individual types of alcohols. The identification of the degradation products confirms the proposed schemes for the photodegradation reactions. The apparatus described can also be used for the study of photolysis kinetics, as it permits the easy and rapid variation of the reaction conditions.