固相萃取-气相色谱法测定北京市水样中的邻苯二甲酸酯

研究了使用毛细管柱（OV-1701）分离、FID作为检测器的气相色谱法测定水中5种邻苯二甲酸酯（PAEs）[邻苯二甲酸二乙酯（DEP）,邻苯二甲酸二丁酯（DBP）,邻苯二甲酸丁基苄基酯（BBP）,邻苯二甲酸二（2-乙基己基）酯（DEHP）,邻苯二甲酸二环己酯（DCHP）]的色谱条件。5种PAEs检出限在0．1～0．3μg／L之间,所测PAEs的质量浓度在0．5～100μg／L范围内,RSD在2．2％～3．3％之间,各物质校正曲线（质量浓度与峰面积）的相关系数在0．9970～0．9993之间。利用固相萃取技术萃取水中PAEs,回收率在82．5％～110．5％之间,RSD在1．1％～4．0％之间。北京市吴家村污水处理厂4个采样点中邻苯二甲酸酯浓度在（0．7～193．3）μg／L之间。北京市南护城河的3个采样点中邻苯二甲酸酯浓度在（0．1～241．8）μg／L之间。     

A new catalyst for direct synthesis of dimethyl ether from synthesis gas

A new catalyst has been prepared by coprecipitation sedimentation method developed in our laboratory. It exhibits excellent catalytic activity, selectivity and stability for conversion of synthesis gas to dimethyl ether: conversion of CO 92%, selectivity of dimethyl ether 98%. Catalytic properties of the catalyst show no evident change after being used for 100 h.     

Bioaccumulation study of acrylates in algae (<Emphasis Type="Italic">Chlorella kessleri</Emphasis>) by Py-GC and Py-GC/MS

Acrylate monomers methylmethacrylate (MMA) and cyclohexylmethacrylate (CHMA) bioaccumulation has been determined in aquatic organism, algae (Chlorella kessleri). Algae were collected in amount of 0.4 mg and directly injected to the pyrolytical cell. In algae bodies accumulated monomers were analysed by pyrolysis gas chromatography (Py-GC) and pyrolysis gas chromatography coupled with mass spectrometry (Py-GC/MS). Traces of the accumulated monomers in algae body can be determined after 1-, 2-, 3-weeks of incubation. Maximum content of MMA was determined after 3-week of experiment, contrariwise in the case of CHMA after 2-week exposition. Relationship with pyrolysis temperature has also been studied.     

Facial selectivity of the (R)-1,3-dimethyl-1-cyclohexyl cation in the gas phase

The model reaction between the (R)-1,3-dimethyl-1-cyclohexyl cation (I) and methanol has been investigated under gas-phase radiolytic conditions (750 Torr; 25-120 degrees C) with the aim of evaluating the intrinsic factors that govern the facial selectivity of biased carbocations. The peculiarity of the experimental approach allows the formation of different CH(3) (18)OH.I ionic adducts. Subsequent conversion of these adducts to give the corresponding E/Z covalent products follows different reaction coordinates, which are characterized by their own activation parameters. On the grounds of density functional theory (DFT) results, several [CH(3)OH.I] structures have been located on the relevant potential-energy surface (PES). The experimental results point to a gas-phase facial selectivity, which is mainly governed by entropic factors that arise as a result of the occurrence of different noncovalent ion-molecule "facial adducts" (FA). The formation of FAs may also play an important role in both the reaction dynamics and the positional selectivity. The present results cannot be interpreted by any of the models based on solution-phase experiments.     

基于氦离子化气相色谱法测定微量氧、氮的影响因素

探讨氦离子化气相色谱法测定样品中微量氧、氮含量的影响因素。采用控制变量法,对色谱柱温度、进样流量、进样管道环境及极化电压等因素对微量氧、氮测定结果的影响进行讨论和分析。结果表明,当色谱柱温度为25~45℃时,色谱柱对氧、氮吸附量最小;当进样流量不小于70 mL/min时,微量氧、氮测定结果受外界干扰最小;当极化电压为80~160 V时,氧、氮具有最佳的响应值;初次测定样品中微量氧、氮含量时,需使进样管道表面吸附的氧、氮处于饱和状态,以便获得理想的测定结果。讨论的结果可为氦离子化气相色谱法测定相关样品中微量氧、氮含量时提供技术参考。     

Elution behaviour and environmental impact of heavy metals and rare-earth elements from volcanic ashes of Mt. Oyama,Miyake Island

To obtain information on the environmental impact of materials eluted from volcanic ashes of Mt. Oyama, Miyake Island, which erupted in July 2000, the dissolution behaviours of heavy metals and rare-earth elements from the volcanic ashes were examined. The most important characteristic of the Mt. Oyama eruption is that sulphur dioxide (SO₂) gas has been continuously released, and all persons living on Miyake Island have been required to evacuate. To estimate in terms of the volcanic eruption using SO₂ gas, the ash nature in Mt. Usu, Hokkaido, was also examined and compared with that in Mt. Oyama. When rain water mixed the ashes, the water from the ashes of Mt. Oyama became acidic because of the sulphuric acid. Therefore, SO₂ gas in Mt. Oyama can accelerate the dissolution of protons and heavy metals in the ashes, whereas the rain water in Mt. Usu was not acidic and the dissolution of the heavy metals was not so evident compared with that in the case of Mt. Oyama. With this sulphuric acid, heavy metals such as As, Cd, Pb and Hg in the ashes in Mt. Oyama easily dissolved owing to the low pH. The ashes in Mt. Oyama had been released for eight years and the amount of fallen ashes was estimated to be 33 billion tons. The weights of the harmful heavy metals in the volcanic ashes, such as As, Cd, Pb and Hg, were estimated to be 3.8?×?10², 1.3?×?10³, 1.1?×?10³ and 29?kg, respectively, and these heavy metals were dissolved and diluted in seawater. Therefore, the concentration and species (chemical form) of these metals should be carefully monitored in the future. Moreover, SO₂ gas, which has a direct effect on human health and has been monitored continuously, causes other effects, such as facilitation of metal ion elution and rock aeration.     

Near- and mid-infrared laser-optical sensors for gas analysis

Semiconductor diode lasers were first developed in the mid-1960s and found immediate application as much needed tunable sources for high-resolution laser spectroscopy commonly referred to as tunable diode laser absorption spectroscopy (TDLAS). In this paper, currently available semiconductor lasers for spectroscopy in the near- and mid-infrared spectral region based upon gallium arsenide, indium phosphite, antimonides and lead-salt containing compounds will be reviewed together with the main features of TDLAS. Room-temperature measurements of atmospheric carbon dioxide near 2 μm will be discussed and recent results obtained with a fast chemical sensor for methane flux measurements based on lead-salt diode lasers operating near 7.8 μm will be presented.     

水平管液塞区相分布特征研究

设计建造了研究段塞流中液塞卷吸气体的实验装置,采用双头电导探针测量了水平管内固定液塞区域的局部相分布。液塞区含气率的径向分布存在峰值,表明液塞区存在湍流剪切层。随着进入液塞距离增大,含气率峰值减小,峰值对应的径向位置升高。这说明湍流剪切层内的湍流程度减弱,剪切层厚度变大。提出了计算水平管液塞截面平均含气率的方法,发现随着进入液塞距离的增大,截面平均含气率首先迅速减小,然后逐渐趋于稳定。     

双重净化-气相色谱法测定植物油中指示性多氯联苯

为了考察食用油中7种指示性多氯联苯(PCBs)的残留情况,建立了食用油中痕量多氯联苯测定的双重净化-气相色谱法。以乙腈提取样品,提取液浓缩至干后用正己烷溶解,经浓硫酸、硅胶分散固相萃取双重净化后进行气相色谱分析,外标法定量。优化的色谱条件为:HP-5石英毛细管柱(30 m×0.32 mm×0.25 μm)程序升温分离,流速0.8 mL/min,进样量1.00 μL,电子捕获检测器检测。结果表明:在优化的条件下,7种多氯联苯在10~500 μg/L范围内线性良好,相关系数大于0.999,不同基质中的检出限(S/N=3)范围为1.8~8.9 μg/kg,定量限(S/N=10)范围为5.9~29.8 μg/kg。在橄榄油、花生油和棕榈油空白样品中添加10、20、100 μg/kg 3个水平的7种多氯联苯,其加标回收率范围为71.0%~105.5%,相对标准偏差(RSD)范围为4.0%~11.3%。该方法具有操作简便、快速、准确的特点,可用于植物油中指示性多氯联苯残留量的日常检测。