二次热解吸测定室内空气中TVOC的方法研究

总挥发性有机化合物(Total Volatile Organic Compound,TVOC)用于评价室内空气中多种挥发性有机化合物的污染水平,可以比较全面地反映室内空气的污染程度,是评价室内空气质量的重要指标.TVOC是评价室内空气质量的重要指标.GB 50325-2001中规定TVOC吸附管的热解吸方法为手工进样法或直接进样法.二次热解吸是在直接进样法的基础上增加二次吸附.热解吸,可有效改善各化合物色谱峰形,提高测量的重现性.二次热解吸仪与进口热解吸仪相比,价格低廉,易于维护,运行成本也较低.     

车间空气中二甲基乙酰胺、丁酮和癸烷的气相色谱分析

采用Tenax吸附管吸附车间空气中的二甲基乙酰胺、丁酮和癸烷（十烷）,经热解吸,样品在SE30大口径毛细管气相色谱柱上分离,外标法峰面积定量,系统分析了这三种挥发性有机化合物的含量。研究表明,这三种有机物经热解吸后的回归曲线的相关系数均在0．992以上,Tenax管吸附效率达90％以上,热解吸率达85％以上,样品的平均回收率为85％～110％。     

热脱附-气相色谱-质谱法测定聚氨酯发泡床垫中12种挥发性有机化合物北大核心CSCD

采用热脱附-气相色谱-质谱法测定聚氨酯发泡床垫中12种挥发性有机化合物的含量。采用挥发性有机化合物的环境气候箱模拟室内环境,用含有Tenax TA的吸附管收集释放出的挥发性有机化合物。在气相色谱分离中采用DB-5MS毛细管色谱柱,在质谱分析中采用全扫描模式。12种挥发性有机化合物的质量在一定范围内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为1.0μg·m^(-3)。加标回收率为84.3%～106%,测定值的相对标准偏差(n=6)为8.0%～9.8%。     

吸附/一级热解吸/气相色谱联用测定室内空气中的挥发性有机物

本文以高聚物TenaxTA动态吸附,一级热解吸/毛细管气相色谱法联用测定室内空气中的挥发性有机物。优化了热解吸温度和热解吸时间,建立了苯、甲苯、乙酸正丁酯、乙苯、对二甲苯、苯乙烯、邻二甲苯、正十一烷等8种典型有机污染物的外标定量曲线,各化合物线性范围为103,相关系数R为0.9983～0.9999,最低检出浓度可达2×10-4mg/m3;考察了方法的重复性、热解吸率和残留率,并分析了实际空气样品。     

23种挥发性有机化合物在3种吸附剂上漏出容量的测定评价

采用吸附热解吸－气相色谱－质谱法对23种挥发性有机化合物Chromosorb 106、Tenax TA、Tenax TG等3种吸附剂上漏出容量进行了测定。根据实验结果确定了不同的化合物应选择不同的吸附剂及相应的采样体积。结果表明,Chromosorb 106可较好地吸附低沸点的挥发性有机化合物,Tenax TA、Tenax TG均可用于沸点较高的挥发笥有机化合物吸附,这对测定大气中的有机化合物含量采样有一定的参考价值。     

室内空气中挥发性有机化合物污染及检测方法

室内空气中挥发性有机污染物的释放严重影响了室内空气质量,本文较详细的叙述了这些有机污染物的来源、种类及处理方法等,并对空气中VOCs的采集和检测方法作以介绍,阐述了不同机制的热解吸仪与气相色谱联用时的优缺点及其应用．     

吹扫捕集-气相色谱-质谱联用法测定农作物种子表面挥发性有机化合物

提出气相色谱-质谱联用法测定农作物种子表面的挥发性有机化合物的方法。样品经吹扫、捕集及热解吸后,于气相色谱-质谱分析仪测定,内标法定量。二氯甲烷、1,2-二氯乙烷、氯苯、1,2,4-三氯苯和萘5种挥发性有机化合物的质量浓度与其峰面积在一定的浓度范围内呈线性关系,方法的检出限(3s)在0.20~0.40μg.kg-1之间。标准加入平均回收率在86.5%~96.3%之间,相对标准偏差(n=7)均小于5.5%。     

活性炭吸附–热脱附–气相色谱法测定室内空气中5种挥发性卤代烃

建立活性炭吸附–热脱附–气相色谱法测定室内空气中三氯甲烷、四氯化碳、三氯乙烯、四氯乙烯、三溴甲烷5种挥发性卤代烃含量的方法。选用活性炭为固体吸附剂,热脱附进样,温度为300℃,时间为3 min,捕集阱温度为–5℃,采用配有FID检测器的气相色谱仪检测,以保留时间定性,外标法定量。5种卤代烃的质量浓度在20～500μg/m~3范围内与色谱峰面积有良好的线性关系,相关系数大于0.998,方法检出限为2.7～5.3μg/m~3。样品加标回收率为82.6%～107.5%,测定结果的相对标准偏差为7.3%～13.6%(n=6)。该法具有操作简便,结果准确、可靠等优点,可用于室内空气中挥发性卤代烃的检测。     

顶空气相色谱-质谱法测定废水中挥发性有机化合物和卤化溶剂

建立顶空气相色谱–质谱法测定废水中挥发性有机化合物和卤化溶剂的含量。样品采用DB–624色谱柱净化,以顶空方式进样,用气相色谱–质谱法对挥发性有机化合物和卤化溶剂进行测定,外标法定量。挥发性有机化合物和卤化溶剂的含量在0.01～2.0μg范围内与峰面积呈良好的线性关系,相关系数均大于0.998,方法检出限为0.1μg/L。测定结果的相对标准偏差为1.30%～2.22%(n=6),样品加标回收率为85.3%～106.4%。该方法简单、快速,结果准确、可靠,适用于废水中挥发性有机化合物和卤化溶剂的测定。     

环境舱-热脱附-气相色谱/质谱联用法测定软体家具面料中40种挥发性有机物

建立了同时检测软体家具面料中40种挥发性有机物的环境舱-热脱附-气质联用(ETC-ATD-GC/MS)检测方法。以Tenax TA吸附管吸附环境舱内不同面料中释放的挥发性有机物,经热脱附仪加热,将挥发性有机物脱附后随载气进入GC/MS进行定性和定量分析。考察了吸附管脱附温度、脱附时间,冷阱温度等不同参数对挥发性有机物的脱附效率的影响。结果表明,40种挥发性有机物在2~200 ng质量范围内呈良好的线性关系,相关系数在09949~0.9999之间,方法的检测限为0.011~0.277μg/m~3。方法回收率为88.0%~109.9%,相对标准偏差在1.5%~9.5%之间。方法适用于不同软体家具面料中挥发性有机物的定量分析。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.