烷类特种气体分析装置的研制及其应用

研制烷类特种气体分析专用的多维气相色谱仪，特制的热导检测器，具有手动－自动功能。设计了输气－配气装置和多维气相色谱流程。以微机控制，可按编辑程序清洗系统。检查本底，自动进样，显示或打印谱图和分析结果。可检测多种烷类特种气体组份及其中氧，氮，一氧化碳和甲烷等痕量杂质。     

Comparison of combustion sources for sulfur chemiluminescence detection

Three different types of SCD combustion source have been evaluated for use in the chromatographic analysis of atmospheric sulfur compounds. The conventional FID source and the newer inverted burner source were found to be less sensitive and less stable than the flameless design. Overall, the flameless source was superior for use with HRGC-SCD.     

A new method for characterizing solid surface acidity - an infrared spectroscopic method using probe molecules such as N2 and rare gases

A new infrared-spectroscopic method to characterize acid sites of zeolites using small and weakly basic molecules such as diatomic and monoatomic molecules is reviewed. It has been revealed that N2 is an effective probe molecule to characterize both Brønsted acidity and Lewis acidity of H-form zeolites. The characteristics of the N 2 probe are discussed in detail in comparison with the CO probe. O2 and rare gases have also been applied to monitor the strong acid sites in the H-form zeolites. Further, the studies of the adsorption of water on H-form zeolites are shortly reviewed: a recent IR study of the H₂ ¹⁸O adsorption on H-ZSM-5 has given direct experimental evidence that the main feature of the observed IR bands is due to the hydrogen-bonded adsorption of water on the Brønsted acid sites.     

Enthalpies of aqueous solution of noble gases at 25°C

The standard enthalpies of solution of rare gases (helium, neon, argon, krypton, and xenon) in water at 25°C have been measured by a high precision steady-state calorimetric method. The aqueous solvation process is energetically favorable at 25°C for the gases studied. Values of the standard free energy, enthalpy, and entropy changes are found to be well correlated with cavity surface areas and the number of water molecules in the first solvation shell. Also, the values of the standard enthalpy and entropy of solution for the rare gases are found to have the same dependence on the number of solvation shell water molecules as inorganic and hydrocarbon gases. These results imply that the dominant source of enthalpy and entropy change resides in the first solvation shell.     

Separation of mixtures of permanent gases and light hydrocarbons on spherical carbon molecular sieves by gas-solid chromatography

Summary Experimental results are presented on the application of Carbosieve S (Supelco) and Spherocarb (Analabs) spherical carbon molecular sieves for the gas chromatographic separation of mixtures of permanent gases and C₁–C₃ hydrocarbons using a single column or two columns in series. At a programmed temperature of 35–300°C, good separation of the sample components was obtained when using helium as the carrier gas. When hydrogen was used as the carrier gas and the analysis was carried out under isothermal conditions the elution sequence of oxygen and nitrogen reversed as the temperature was increased. This behaviour was observed within a temperature range of 35–225°C for Carbosieve S, and within a temperature range of 35–300°C for Spherocarb.     

Oxygen chemisorption on divalent chromium ions in chromosilicate systems

A study has been made of the chemisorption of O₂ from various gaseous media on divalent chromium ions in chromosilicate systems under dynamic conditions. After passing through the chemisorbent layer the residual O₂ content of the gaseous mixtures is 10^–6–10^–7 vol. %. The adsorption capacity of the chemisorbents increases in proportion to their Cr(II) content and decreases as the moisture content increases in the gas mixture from which the oxygen is absorbed. The chemisorbents can be repeatedly regenerated by treating them with hydrogen.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2500–2505, November, 1992.     

Application of HPLC to measure vanadium in environmental,biological and clinical matrices

Vanadate and vanadium compounds exist in many environmental, biological and clinical matrices, and despite the need only limited progress has been made on the analysis of vanadium compounds. The vanadium coordination chemistry of different oxidation states is known, and the result of the characterization and speciation analysis depends on the subsequent chemistry and the methods of analysis. Many studies have used a range of methods for the characterization and determination of metal ions in a variety of materials. One successful technique is high performance liquid chromatography (HPLC) that has been used mainly for measuring total vanadium level and metal speciation. Some cases have been reported where complexes of different oxidation states of vanadium have been separated by HPLC. Specifically reversed phase (RP) HPLC has frequently been used for the measurement of vanadium. Other HPLC methods such as normal phase, anion-exchange, cation-exchange, size exclusion and other RP-HPLC modes such as, ion-pair and micellar have been used to separate selected vanadium compounds. We will present a review that summarizes and critically analyzes the reported methods for analysis of vanadium salts and vanadium compounds in different sample matrices. We will compare various HPLC methods and modes including sample preparation, chelating reagents, mobile phase and detection methods. The comparison will allow us to identify the best analytical HPLC method and mode for measuring vanadium levels and what information such methods provide with regard to speciation and quantitation of the vanadium compounds.     

Fast-cycle trace analysis of dioxin in flue gas. Monitoring of the incineration of dioxin-containing waste from seveso

The fast trace analysis method used to monitor 2,3,7,8-TCDD in stack gas during the incineration of the waste from Seveso is described. The sampling of volatile organic compounds from flue gases, distributed between all three aggregation states, is based on a micromethod developed for the trace analysis of water using a specially dimensioned adsorptive charcoal filter (1.5 mg charcoal). In conjunction with subsequent GC/MS measurements the rapid “fast cycle trace analysis” ensured specific 2,3,7,8-TCDD detection down to 100 pg per m³ flue gas in cycle times of about 1–2 hours.     

Gas permeability and permselectivity of fluorinated polybenzoxazoles

Gas permeability and permselectivity are investigated for polybenzoxazoles from bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (BAHHP) and aromatic diacid chlorides. Effects of thermal cyclization on the permeation properties are also investigated. The polybenzoxazole from BAHHP and 4,4′-(1,1,1,3,3,3-hexafluoroisopropylidene)dibenzoyl chloride (HFDB) displays high performance for CO₂/CH₄ separation ( $ {\rm P}_{{\rm CO}_2 } $ = 6.1 × 10^?9 cm³ (STP) cm^?1 s^?1 cm-Hg^?1, and $ {{{\rm P}_{{\rm CO}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm CO}_2 } } {{\rm P}_{{\rm CH}_4 } }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CH}_4 } }} $ = 38 at 35°C). The polybenzoxazole from BAHHP and 2,6-naphthalene dicarbonyl chloride displays high performance for H₂/CO or H₂/CH₄ separation ( $ {\rm P}_{{\rm H}_2 } $ = 2.4 × 10^?9 cm³ (STP) cm^?1 s^?1 cm-Hg^?1, $ {{{\rm P}_{{\rm H}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm H}_2 } } {{\rm P}_{{\rm CO}} }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CO}} }} $ = 71, and $ {{{\rm P}_{{\rm H}_2 } } \mathord{\left/ {\vphantom {{{\rm P}_{{\rm H}_2 } } {{\rm P}_{{\rm CH}_{\rm 4} } }}} \right. \kern-\nulldelimiterspace} {{\rm P}_{{\rm CH}_{\rm 4} } }} $ = 250). Permeation properties for the polybenzoxazole from BAHHP and HFDB are close to those for a polyimide of similar chemical structure. The permeation properties are discussed in connection with packing density and local segmental mobility. © 1992 John Wiley & Sons, Inc.     

Gastrennung mit Hilfe des Zirkulations-Diffusions-Verfahrens Teil I : Hochanreicherung von Gasen in Trennrohren mit natürlicher Zirkulation

Auf der Grundlage des Zirkulations-Diffusions-Prinzips wurden zwei Trennrohre für die Hochanreicherung von Gasen enytwickelt. Als Modellgasmischungen dienten H₂-N₂ Kr-CH₄ und Luft. Neben Wasserdampf wurden Methanol- und Äthaanoldämpfe als Treibmittel benutzt. Gute Trennungen wurden in einem nur 20 cm langen Rohr erzielt, dessen Trennspalt horizontal durch Lamellen in kleine Sektionen und durch ein Drahtdiaphragma vertikal in zwei Ringkammern geteilt wird. Drei Rohre dieses Typs wurden in einer rechteckigen Kaskadenanordnung getestet. Die Theorie des Transportes im Trennrohr sowie die Behandlung des hydrodynamischen Problems werden angegeben. Eine Anwendung des beschriebenen Trennrohres zur Isotopentrennung und zur Gashochanreicherung erscheint aussichtsreich.