固相微萃取-气相色谱联用测定饮料中残留的10种可挥发性卤代烃

建立了固相微萃取(SPME)与气相色谱(GC)联用测定饮料中残留的可挥发性卤代烃(VHH)的检测方法.探讨了影响SPME萃取效果的纤维涂层、离子强度、萃取时间等因素,并对饮料样品的预处理进行了研究.方法的检出限0.3μg/L,线性范围3～90μg/L,回收率在79.5%～104.3%之间,RSD在1.3%～12%之间.     

三苄基杯[6]芳烃固相微萃取复合涂层的研制及其应用

采用溶胶-凝胶方法制备了三苄基杯[6]芳烃/羟基硅油(C[6]/OH-TSO)固相微萃取(SPME)探头, 通过对多环芳烃和酞酸酯(PAEs)的分析考察了新型C[6]/OH-TSO探头的性能. 结果表明: 杯[6]芳烃SPME探头对这些非极性和弱极性的芳香化合物有很好的萃取效果和选择性, 具有耐高温、使用寿命长等特点. 建立了SPME与气相色谱-氢火焰(GC-FID)联用测定化妆品中PAEs的方法. 该方法检测限低, 重现性好(RSD＜9%), 线性范围宽(2～3个数量级). 回收率在83.42%～98.85%之间.     

顶空固相微萃取-气相色谱质谱联用测定烷基铅的研究

建立了顶空固相微萃取(HS SPME)与气相色谱 质谱(GC/MS)联用测定水样中四甲基铅和四乙基铅的方法,探讨了SPME萃取烷基铅的实验条件,并对GC/MS条件进行了优化。结果表明:四甲基铅和四乙基铅分别在5～1000ng/mL和1～500ng/mL范围内有良好的线性关系,检出限分别为四甲基铅5.19ng/mL,四乙基铅1.05ng/mL。方法用于合成水样分析,四甲基铅和四乙基铅的回收率在87.5%～110.6%之间,相对标准偏差在1.7%～6.5%之间。     

介孔涂层固相微萃取-高效液相色谱法测定水样中邻苯二羧酸酯化合物

以苯基官能化MCM-41介孔复合体作为固相微萃取(SPME)的吸附涂层, 与高效液相色谱(HPLC)联用测定了不同水样中邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二辛酯(DOP)的含量, 对SPME的吸附和解吸时间、温度、搅拌速度进行了优化, 线性范围分别为1.19×10-4～119 μg/L、 1.12×10-4～112 μg/L、 1.05×10-4～105 μg/L和9.80×10-5～98 μg/L, 检出限依次为0.030、 0.027、 0.029和0.022 ng/L. 使用该方法测定了多种水样中邻苯二羧酸酯类化合物.     

固相微萃取-气相色谱法测定涂料中苯系物

采用固相微萃取(SPME)技术结合气相色谱法对涂料中的苯系物进行检测和分析,针对涂料中存在的主要污染物,对影响SPME的参数进行了优化.建立的方法在所测的范围内具有良好的线性(相关系数:0.9991～0.9996);检出限达0.05～0.60 μg/L;重复测定的相对标准偏差小于2.3%.     

固相微萃取-气相色谱-质谱联用分析环境水样中痕量有机磷农药

研究了固相微萃取(SPME) 气相色谱 质谱联用(GC MS)同时测定环境水样中二嗪农、甲基对硫磷、对硫磷和水胺硫磷4种有机磷农药(OPPs)的分析方法。选择聚丙烯酸酯(PA)萃取纤维,对SPME的条件如萃取时间、萃取溶液的pH值和离子强度、解吸温度、解吸时间和GC MS的条件进行了优化。对二嗪农和水胺硫磷方法线性范围为0.001～10μg L,对甲基对硫磷和对硫磷方法线性范围为0.001～100μg L。二嗪农、甲基对硫磷、对硫磷、水胺硫磷的检出限分别为0.015,0.020,0.013和0.039μg L。分析加标自来水、矿泉水和湖水样品,回收率在89.0%～102%之间,RSD在2.1%～14.1%之间。适合于环境水样中痕量OPPs的快速分析。     

镍钛合金表面离子液体掺杂聚苯基吡咯纤维涂层的制备及其对多氯联苯的高效固相微萃取

采用水热法和电沉积法在镍钛(NiTi)合金表面构筑1-丁基-3-甲基咪唑六氟磷酸盐离子液体(IL)掺杂聚苯基吡咯(PPPy)纤维涂层,成功制备了新型IL@PPPy-TiO_2/NiOCNSs固相微萃取(SPME)纤维。将该新型纤维与高效液相色谱(HPLC)联用,以多氯联苯(PCBs)、邻苯二甲酸酯(PAEs)、多环芳烃(PAHs)和紫外线(UV)吸收剂为模型分析物评价其萃取性能。结果显示,该纤维对PCBs有较强的萃取选择性和较高的萃取效率。在优化条件下,5种PCBs在一定质量浓度范围内呈良好线性,相关系数r≥0.998 6,检出限(LOD)为0.015～0.11μg/L。采用单支纤维在同日和隔日对50μg/L PCBs混合标准溶液进行萃取测定,相对标准偏差(RSD)分别为4.7%～6.1%和5.4%～7.0%,相同方法制备的5支纤维测定的RSD为6.5%～7.7%。实际水样的加标回收率为83.0%～104%,RSD不大于8.6%。所建立的SPME/HPLC法适用于不同环境水样中痕量PCBs的快速萃取和高效测定。     

有机硅改性聚酰亚胺固相微萃取涂层的制备及其应用

以N,N-二甲基甲酰胺为溶剂,用3,3′,4,4′-二苯甲酮四羧酸二酐、4,4′-二氨基二苯醚及1,3-双(3-氨基丙基)-1,1,3,3-四甲基二硅氧烷合成了有机硅改性的聚酰亚胺作为固相微萃取(SPME)中基质(石英纤维)的涂层材料。通过红外光谱法、热重法及扫描电子显微镜对此涂层的结构、热稳定性和表面形貌进行了分析,证明了通过聚合反应将有机硅链段引入到聚酰亚胺结构中可增加链的柔韧性,减少分子链间的极性作用,改善其吸附性能,而且经高温脱水反应使涂层键合在石英纤维表面,使其性质稳定,不易脱落。将有此涂层的SPME应用于气相色谱法测定水中7种苯系物,取得良好的分离效果,7种苯系物测定值的相对标准偏差(n=6)在4.1%~6.0%之间,检出限(3S/N)在0.02~0.11mg·L-1之间,回收率在98.0%~117%之间。     

顶空固相微萃取-气相法测定酒中的甲醇和杂醇油

 采用环氧树脂作为固相涂层制作固相微萃取 (SPME)装置 ,建立了顶空固相微萃取 气相法 (HS SPME GC)测定酒精饮料中甲醇和杂醇油的方法 ,并对萃取条件和条件进行了优化。方法的检出限为 0 0 2mg/L～0 0 4mg/L ,相对标准偏差为 1 4 %～ 4 1% ;与顶空气相法相比 ,灵敏度可提高 2 0倍～ 30 0倍。将该法用于啤酒、葡萄酒和保健酒中的甲醇和杂醇油的测定 ,加标回收率为 80 8%～ 110 3% ;与顶空气相法 (国家标准方法 )进行了比较 ,相对误差不大于 7 3%。该法简便、快速、灵敏、精密度好 ,拓宽了SPME的应用范围。     

固相微萃取气相色谱法测定水产品中五氯苯酚及其钠盐残留量

采用自动固相微萃取(Automated SPME)超声波辅助萃取技术(UE)与气相色谱联用测定水产品中五氯苯酚及其钠盐残留量.实验优化了SPME直接萃取技术,样品调pH 2,超声波40℃萃取30 min后,用85μm聚丙烯酸酯(PA)萃取头90℃自动搅拌萃取30 min,270℃解吸5 min.最低检出量为0.01μg/kg;五氯苯酚线性范围0.001～10 μg/L,r=0.9999;对鳕鱼加标五氯苯酚1.0、5.0μg/kg回收率分别为71.0%～80.0%、77.2%～91.4%,相对标准偏差(RSD)为6.3%和8.6%(n=3).该方法简便、灵敏、稳定,无溶剂污染,是测定水产品中五氯苯酚及其钠盐残留量的理想方法.     

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.     

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.