吹扫捕集-GC／MS测定水中的挥发性卤代烃和苯系物

以吹扫捕集系统富集,PONA毛细管柱分离,GC/MS法测定水中的挥发性卤代烃和苯系物。对色谱柱的选择,吹扫流量、时间以及解析时间等影响因素进行了优化选择。方法实现了对水中苯、乙苯、对、间二甲苯、邻二甲苯、甲苯、苯乙烯、三氯化碳、四氯化碳、三氯乙烯、四氯乙烯等挥发性卤代烃和苯系物的同时富集和测定,成功分离了苯乙烯和邻二甲苯。方法平均回收率为90%~105%,检出限为0.017~0.194μg/L,精密度(RSD)为1.8%~4.3%(n=6)。方法可用于水中挥发性卤代烃和苯系物的同时测定。     

顶空毛细管柱气质联用法测定饮用水中15种挥发性有机物

采用顶空毛细管柱GC–MS法测定饮用水中卤代烃、苯系物、氯苯等15种挥发性有机物。色谱柱为DB–624石英毛细管柱(60 m×0.25 mm,1.8μm),程序升温,直接进样顶空毛细管柱气质联用法同时测定饮用水中15种挥发性有机物。该方法具有良好的线性,线性相关系数均大于0.996。方法的检出限为0.10~0.22μg/L。15种挥发性有机物的平均回收率在94%~103%之间,测定结果的相对标准差为2.9%~6.7%(n=7)。该方法简便、快速,检测结果均能满足GB 5749–2006检测要求。     

气相色谱-质谱法测定汽车材料中7种苯系物

采用气相色谱-质谱法测定汽车材料中7种苯系物的含量。在气相色谱分离中用HP-5MS色谱柱为固定相,在质谱分析中采用全扫描和选择离子监测模式。以氘代苯-D6为内标物。7种苯系物的线性范围均为1 0~1 000ng,检出限(3s)在9~18ng之间。苯系物测定结果的相对标准偏差(n=6)在0.81%~2.4%之间,加标回收率在99.0%~102%之间。     

吹扫捕集-气相色谱-质谱法测定地下水中的挥发性有机物

采用吹扫捕集-气相色谱-质谱联用技术,建立了适用于地下水中卤代烃、氯代苯和苯系物等27种挥发性有机污染物的分析方法。水样经吹扫捕集后,待测物在Rtx-5MS毛细管色谱柱上分离,质谱分析中采用电子轰击离子源和选择离子监测模式,内标法定量。考察了不同解析时间、不同分流比以及固定剂盐酸对测定的影响。27种挥发性有机物的线性范围均为0.4~40μg·L~(-1),检出限(3s)在0.10~0.32μg·L~(-1)之间。加标回收率在91.6%~111%之间,测定值的相对标准偏差(n=7)在1.3%~8.8%之间。     

热脱附-气相色谱-质谱法测定胶粘剂中苯系物的释放量

将胶粘剂样品置于模拟实际环境的气候箱中,在280℃条件下解吸5min,脱附的苯系物气体引入DB-1MS毛细管色谱柱进行分离并进入质谱仪进行测定。质谱分析中采用电子轰击离子源(EI)和选择离子监测(SIM)模式。6种苯系物的质量在10.73~1 216ng之间呈线性,最低检出浓度(以采样体积5.0L计)为0.2μg·m~(-3)。用标准加入法测得6种苯系物的回收率在87.8%~105%之间,测定值的相对标准偏差(n=8)在8.2%~11%之间。     

气相色谱法分离和测定溶剂型木器涂料中正丁醇与苯系物

在气相色谱法测定溶剂型木器涂料中正丁醇及苯系物(包括苯、甲苯及二甲苯)时采用了VF-200MS型号的毛细管色谱柱。由于此型号的毛细管柱具有较强极性,不仅能达到正丁醇与苯系物之间的有效而满意的分离,而且还能使苯系物(包括苯、甲苯、乙苯、二甲苯)之间和二甲苯的同分异构体之间的有效分离。测定中采用正戊烷作内标和用火焰离子检测器检测。此方法的检出限(2S/N)在1.7~3.5 ng之间。用一含有正丁醇的硝基漆样品按所提出的方法进行多次重复测定,并在此样品的基础上加入各被测化合物的标准后进行测定,从而对方法的回收率和精密度作了测试,测得其回收率在87.8%~100.0%之间,测定值的相对标准偏差(n=6)均小于2.5%。     

高效液相色谱法测定建筑用胶中苯系物和邻苯二甲酸酯类增塑剂

采用高效液相色谱法同时测定建筑用胶中苯系物和邻苯二甲酸酯类增塑剂。样品以乙酸乙酯为萃取剂超声提取,采用C18柱为固定相,乙腈、水为流动相进行梯度洗脱,采用二极管阵列检测器,在254 nm处测定。5种苯系物和5种邻苯二甲酸酯类增塑剂的峰面积与其质量浓度呈线性关系,线性范围在1~3个数量级之间,对苯系物的检出限(3S/N)在0.003~0.006 g.L-1之间,对邻苯二甲酸酯类增塑剂的检出限(3S/N)在0.003 g.L-1之内。对水基型和溶剂型建筑用胶中各物质的回收率在98.1%~101.9%之间。5个实验室间对相同建筑用胶样品中不同目标物测定的相对标准偏差(n=6)在0.8%~4.2%之间。     

顶空-气相色谱法测定海水中8种苯系物

提出了顶空-气相色谱法测定海水中残留的8种苯系物的方法。分别选择40℃及30min作为样品在顶空瓶中的平衡温度和平衡时间。选用Nukol毛细管色谱柱(30m×0.25mm,0.25μm)分离,氢火焰离子化检测器测定。8种苯系物在13min内能完全分离。8种苯系物的质量浓度在10.0～200μg.L-1范围内与其峰面积呈线性关系,检出限(3S/N)均为2μg.L-1。以海水样品为基体,在3个浓度水平上进行加标回收试验,回收率在93%～119%之间,相对标准偏差(n=6)在1.1%～5.3%之间。     

家具白乳胶中苯系物含量测定

建立了气相色谱内标法测定家具白乳胶中苯系物含量的方法。样品中苯系物经甲醇提取、离心,上清液用60 m EN-20色谱柱分离,气相色谱检测,内标法定量。优化条件下苯系物回收率在96.84%~103.86%,相对标准偏差(RSD)为0.79%~2.28%,定量下限2.4~2.9 mg/L。方法操作简单,准确度和精密度较高,是一种检测白乳胶产品中苯系物含量的有效方法。     

固相微萃取-气相色谱/质谱联用分析室内空气中的苯系物

自制了一种固相微萃取采样装置,建立了固相微萃取-气相色谱/质谱(SPME-GC/MS)联用测定室内空气中苯系物的分析方法。方法的线性范围为1~300μg/m3,检出限为0.1~0.3μg/m3,RSD(n=6)3.2%~15%。采用该方法研究了广州市内20户新装修民居中苯、甲苯、乙苯、对二甲苯和1,3,5-三甲苯的含量及分布,并探讨了苯系物的来源。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.