四苯基卟啉锌薄膜/K+交换玻璃光波导传感器检测挥发性有机化合物气体

利用Alder法合成了四苯基卟啉锌配合物并对它进行表征;用匀胶机将一定浓度的四苯基卟啉锌溶液做成薄膜固定在钾离子(K⁺)交换玻璃光波导表面研制了高灵敏的四苯基卟啉锌薄膜/K⁺交换玻璃光波导传感器,并对挥发性有机气体进行检测。 实验结果表明,在室温下该传感器对低浓度的苯乙烯、二甲苯、甲苯等蒸气具有一定的响应,其中对苯乙烯的响应最大;能够检测到1×10^-9(V(苯乙烯)/V(空气))的苯乙烯蒸气,其响应和恢复时间分别为2和7 s。 该传感器具有灵敏度高,回复-响应时间快,可逆性等特点。     

车内空气污染物超标堪比“尾气”等

车内空气污染主要来自VOCs。VOCs是熔点低于室温而沸点在50～260℃之间的挥发性有机化合物的总称,包含多种已知对人体有害的致癌物,如苯、甲苯、甲醛、乙醛等。如今普通乘用车内充斥着大量的人造材料,如果这些材料中含有并释放VOCs,加上车内空间狭小且完全密闭,车辆通常在室外温度较高的环境下运行,将使其成为高危地带。     

连续测量水中挥发性有机物的膜进样-单光子电离-质谱仪的研制及其应用

研制了膜进样-单光子电离-飞行时间质谱仪,并应用于水中挥发性有机物(VOCs)的连续在线快速测量.以50 μm硅橡胶膜为富集膜,用蠕动泵和电动切换阀,实现了水中VOCs的自动进样、富集和测量,无记忆效应.采用真空紫外灯发出的10.6 eV的光子,对待测有机物实现单光子电离,无碎片离子,便于根据分子量进行定性分析.苯、甲苯、二甲苯和氯苯等样品的响应时间均低于100 s; 苯的检出限可达3×10-9(V/V),且在10×10-9～1×10-6(V/V)范围内具有良好的线性.将仪器应用于某化工厂排污水的在线检测中,在200 s时间内可检测到20多种10×10-9(V/V)量级的有机物.结果表明: 膜进样-单光子电离-飞行时间质谱在水中VOCs在线检测方面具有广泛应用前景.     

天冬氨酸功能化石墨烯量子点-金复合物的制备及用于毒死蜱、多菌灵和啶虫脒电化学检测

制备了天冬氨酸功能化石墨烯量子点-金复合物并表征了其结构和催化活性。利用天冬氨酸功能化石墨烯量子点与小尺寸纳米金结合产生的高催化活性,通过Au-S键将农药适配体连接到纳米金表面,然后修饰到玻碳电极表面得到电化学生物传感器,构建了测定毒死蜱、多菌灵和啶虫脒的电化学方法。研究表明,农药分子与适配体的特异性结合导致了生物传感器脉冲差分伏安曲线电流的下降,峰电流响应与毒死蜱、多菌灵和啶虫脒的浓度分别在1×10^-11～1×10^-4 mol/L,1×10^-10～1×10^-4 mol/L和1×10^-9～1×10^-5 mol/L呈良好的线性关系,检出限分别为3×10^-11,3×10^-10和3×10^-9mol/L。该方法已成功应用于苹果中毒死蜱、多菌灵和啶虫脒的检测。     

车内空气污染物超标堪比“尾气”

<正>车内空气污染主要来自VOCs。VOCs是熔点低于室温而沸点在50~260℃之间的挥发性有机化合物的总称,包含多种已知对人体有害的致癌物,如苯、甲苯、甲醛、乙醛等。如今普通乘用车内充斥着大量的人造材料,如果这些材料中含有并释放VOCs,加上车内空间狭小且完全密闭,车辆通常在室外温度较高的环境下运行,将使其成为高危地带。车型与VOCs释放没有直接关系,良好的车辆使用习惯可以降低车内的VOCs。消费者不开车时,要充分通风,甚至适当暴晒,让材料中的VOCs充分释放;驾驶过程中,保持适宜温度,建议低于25℃,低温不利于VOCs的挥发;保持     

电冷阱富集-光电离移动质谱快速检测痕量挥发性有机物

采用电动制冷机设计并搭建了一套低温富集-高温解析冷阱装置,与光电离移动质谱联用,实现了大气中痕量挥发性有机物(VOCs)快速、自动富集检测。与传统冷阱制冷方式相比,电动制冷机低温可至!196℃,体积小巧、无制冷剂消耗、便于携带。利用冷阱结合在线质谱分析了苯、甲苯和二甲苯混合气,对冷阱各参数进行了优化,结果表明:冷阱富集后苯、甲苯和二甲苯的信号强度分别提高了212、254和242倍,回收率分别达到98%、87%和85%,单样品分析时间14 min。将电冷阱结合移动式在线质谱直接分析含有39种VOCs的EPA TO-14标准混合气和室内环境空气,仪器灵敏度低于国家对室内空气中VOCs阈值。电冷阱富集在线移动式质谱可以实现大气、室内环境中痕量VOCs快速富集检测,在挥发性有机污染物现场、实时监测中具有重要的应用潜力。     

热脱附-气相色谱-三重四极杆串联质谱法测定环境空气中的挥发性有机物

采用热脱附(TD)结合气相色谱-三重四极杆串联质谱(GC-MS/MS)建立了环境空气中23种挥发性有机物(VOCs)同时检测的分析方法。空气样品通过主动采样的方式富集到装有Tenax-TA填料的热脱附管中,热解吸后在选择反应监测(SRM)模式下用GC-MS/MS进行检测,内标法定量。结果表明,23种VOCs在0.01~1 ng和1~100 ng低、高两个范围内线性关系良好,相关系数(r²)均大于0.99,方法定量限为0.00008~1 μ g/m³。加标水平为2、10和50 ng时,23种VOCs的平均回收率为77%~124%。除了最低加标水平的氯苯,相对标准偏差(RSD, n=6)均小于20%。对市内3个采样点的环境空气进行测定,其中苯、甲苯、乙苯、二甲苯、苯乙烯、1,2,4-三甲基苯和六氯丁二烯均有检出。实验证明,该TD和GC-MS/MS相结合的检测方法具有准确、可靠、灵敏度高等优点,适用于环境空气中VOCs的同时测定。     

偶氮苯-PVP复合薄膜光波导传感器检测苯乙烯

将掺杂偶氮苯（Azo）的聚乙烯吡咯烷酮（PVP）作为敏感试剂,利用旋转甩涂法将其固定在钾离子（K⁺）交换玻璃光波导表面,研制了Azo-PVP复合薄膜/K⁺交换玻璃光波导气敏元件,并对其气敏特性进行研究。实验结果表明,该敏感元件对苯乙烯蒸汽有较好的选择性响应,其最低检测浓度为1.0×10^-8体积比（V/V₀）,响应-恢复时间分别为9 s和24 s。在浓度1.0×10^-81.0×10^-3（V/V₀）范围内,气体浓度与输出光强度之间有较好的线性关系。     

在线质谱仪在车内VOCs现场快速监测中的应用

挥发性有机物(VOCs)影响车内空气质量和驾乘者的身心健康。自主研发的在线挥发性有机物质谱仪(SPI-MS 2000),实现了有机物分子的单光子电离,产生无碎片的分子离子,可实现秒级响应,仪器的质量分辨率优于800 FWHM,质量精度优于0.02 amu,对甲苯的测定限优于3μg/m^3,且在3~8000μg/m^3范围内有良好的线性关系。将该仪器应用于某客车车内空气的在线检测:在5 s内检测到20多种微克~毫克每立方米量级的有机物。该仪器在车内VOCs现场快速监测方面有广泛的应用前景。     

多束毛细管柱–离子迁移率谱检测环境大气中的苯系物

采用多束毛细管柱–离子迁移率谱(MCC–IMS)系统对环境大气中的苯、甲苯、乙苯、二甲苯和苯乙烯5种苯系物进行快速检测。IMS漂移管温度为80℃,载气和漂移气均为洁净空气,测得苯系物的约化迁移率。苯、甲苯、乙苯、二甲苯和苯乙烯分别在0.20~3.00,0.20~2.00,0.15~1.00,0.25~3.00,0.08~1.00 mg/m~3质量浓度范围内线性良好,线性相关系数均不小于0.96。基于3倍噪声计算,苯、甲苯、乙苯、二甲苯和苯乙烯的检出限分别为0.055,0.023,0.017,0.065和0.013 mg/m~3。MCC–IMS法可快速检测混合样品中5种苯系物,其中苯、甲苯和苯乙烯的定量相对误差分别为5.0%,9.4%,0.2%,测定结果的相对标准偏差分别为2.7%,5.0%,6.7%(n=6)。MCC–IMS的单次测量可在3 min内完成。     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。