土壤中痕量水胺硫磷的微波辅助萃取-固相微萃取-GC-MS法测定

研究了微波辅助萃取(MAE)-固相微萃取(SPME)联合萃取、气相色谱-质谱法(GC-MS)测定土壤中水胺硫磷的分析方法；采用正交设计试验优化了微波升温程序、萃取温度、萃取时间、萃取溶剂体积等MAE条件；研究了SPME萃取涂层、萃取时间、解吸温度等对萃取效率的影响；方法的线性范围在1．O～20μg/L之间，检出限为O．49ng/g；测定25、100ng/g加标土壤样品，回收率分别为79％和107％。RSD分别为2．6％和6．5％；方法综合了MAE快速高效和SPME富集浓缩的优点，以水为萃取溶剂，特别适合于固体样品中痕量有机物的分析。     

微波辅助萃取气相色谱-质谱联用测定蔬菜中的扑草净

研究了微波辅助萃取气相色谱．质谱联用测定植物样品中扑草净的方法，比较了几种不同溶剂的微波萃取效率，从而选取二氯甲烷为萃取溶剂，并采用三因素三水平的正交设计试验对溶剂体积、微波辐射时间、微波功率进行了优化。在优化的实验条件下分析了合成菠菜样品，对0．2μg/g和0．02μg/g的合成菠菜样品，回收率分别为99．5％和92．5％，相对标准偏差分别为5．0％和ll％，方法的线性范围为1．0—400ng／g，检出限为0．22ng／g。方法适合于分析植物样品中的扑草净。     

顶空衍生固相微萃取-气相色谱质谱法测定聚碳酸酯树脂中的环境雌激素

建立了固相微萃取-气相色谱质谱联用测定聚碳酸酯树脂中环境雌激素4-枯基苯酚和双酚A的分析方法。优化了固相微萃取纤维、萃取温度和时间、解吸时间、搅拌速度、pH等萃取条件及衍生化温度和时间、衍生化方式等衍生化条件，并对样品浸泡时间、浸泡温度等进行了研究。方法的线性范围为0．05μg/L～1mg／L，4-枯基苯酚和双酚A的检出限分别为50ng／L和0．5ng／L，相对标准偏差（RSD，n=5）分别为5．2％和1．6％，平均回收率（n=3）在90．50％～107．3％之间，该方法简单、快速、灵敏。     

顶空固相微萃取-气相色谱-质谱联用分析纺织品中挥发性有机物

建立了顶空固相微萃取（HSSPME）-气相色谱（GC）-质谱（MS）联用测定纺织品中甲苯、4-乙烯基环己烯、苯乙烯、萘和1-苯基环己烯5种挥发性有机物（VOCs）的分析方法。选择聚二甲基硅氧烷（PDMS）作为萃取涂层，优化了SPME的萃取条件，包括平衡时间、萃取时间、萃取温度、顶空体积、离子强度、搅拌速度、解吸温度和时间以及GC—MS仪器条件。对于甲苯、4-乙烯基环己烯、苯乙烯、萘和1-苯基环己烯方法线性范围分别为0．087～870、3．32～3320、2．28～2280、0．015～150和0．050～50．0ng／g；检出限分别为0．005、0．042、0．670、0．008和0．011ng／g。实际样品加标回收率在80．1％～122％之间，RSD在0．8％～8．6％之间。方法符合纺织品中痕量VOCs的快速分析要求。     

固相微萃取-气相色谱-质谱联用分析水中的痕量扑草净

研究了固相微萃取－气相色谱－质谱联用测定水中扑草净的方法，采用聚丙烯酸酯（PA）萃取头，对影响固相微萃取萃取效率的萃取时间、搅拌速度、pH值以及盐度等进行了优化。在优化实验条件下，方法线性范围在0．1mg/mL-1000ng/mL之间，检出限为1．5ng/L。用该法分析了合成井水、自来水和湖水样品，回收率在85．4％－89．1％之间，相对标准偏差在1．8％－5．2％之间。本方法适合于水中痕量扑草净的分析。     

固相微萃取-原子荧光测定鱼样品中痕量甲基汞

研制了一种用HF处理石英纤维表面的萃取纤维和一次性微量注射器组成的固相微萃取装置，研究了用甲基聚硅氧烷作为萃取头涂层对氢化甲基汞的萃取，得到的最佳条件是：在室温条件下，缓冲液的pH值为5、萃取时间为lh、NaCl的用量为2g、洗脱时间为50min、KBH4质量浓度为60g／L。在上述优化条件下，甲基汞的萃取率可以达到70％，检出限为0.17ng。测定了鱼样品中甲基汞，所测鱼虾中甲基汞的质量分数为12．4～53．4ng／g，加标回收率为87．6％～112．8％。     

固相微萃取-脉冲火焰光度法测定大气及水中的路易氏剂

建立了固相微萃取（SPME）与气相色谱/脉冲火焰光度检测器（GC／PFPD）联用测定大气和水中路易氏剂及其水解产物的方法。探讨了影响SPME萃取效率的萃取头类型、萃取时间、解吸时间等因素。优化了PFPD的条件参数、衍生化试剂及衍生条件。在优化的条件下，路易氏剂衍生产物的响应值与浓度有良好的线性关系。本方法对水中路易氏剂及其水解产物的检出限为0．1μg/L；气体中路易氏剂的检出限为10ng／m^3；水样的加标回收率为96．7％-102．1％；气体样品的加标回收率为94．9％-103．0％；RSD为2．06％。     

微波辅助-顶空液相微萃取/高效液相色谱分析水样中的邻硝基苯酚

建立了基于微波辅助-顶空液相微萃取在线联用、高效液相色谱法测定水样中邻硝基苯酚的分析方法。采用L16(45)正交实验设计对影响萃取的各种因素,如萃取有机溶剂、微波辐射功率、萃取时间、离子强度、样品液体积,进行了优化。优化后萃取条件为,以乙酸丁酯作为萃取溶剂,功率和时间分别为100W和12min条件下,离子强度为0的样品溶液体积为20mL。在优化萃取条件下,邻硝基苯酚的检出限LOD(S/N=3)为0.94μg/L,萃取富集倍数为30,实际水样的加标回收率为85.2%。理论分析和实验结果表明,微波辅助-顶空液相微萃取在线联用方法具有简便、快速、高效、节省溶剂、选择性好、应用范围广的特点。     

茶叶中三氯杀螨醇残留量的微波萃取-固相微萃取-气相色谱快速检测方法

建立了微波辅助萃取-固相微萃取-气相色谱/电子捕获检测法快速测定茶叶中三氯杀螨醇的方法。采用自制的PDMS萃取头,优化了萃取溶剂的种类,微波辐射时间和微波功率等微波辅助萃取条件;研究了SPME萃取时间、搅拌速度、离子强度、解吸温度和解吸时间对萃取效率的影响。方法对三氯杀螨醇的检出限为0.048 ng/mL,线性范围为0.2~200 ng/mL。在优化的实验条件下,对乌龙茶进行添加回收试验,平均回收率为61.3%~72.8%,相对标准偏差为8.0%~16.3%。本方法适合于茶叶中痕量三氯杀螨醇快速检测。     

顶空固相微萃取-气相色谱-质谱测定水中异味化合物

采用顶空固相微萃取-气相色盐／质谱联用测定了水中常见的3种异味化合物，即2-甲基异茨醇、土腥素和β-柠檬醛。研究并讨论了纤维头的类型、盐的种类和浓度、温度、萃取时间、搅拌和解吸时间等因素对异味化合物萃取量的影响。结果表明：在水样中加入30％（W／V）的NaCl溶液，采用65μm PDMS／DVB纤维头，在搅拌的条件下，于60℃顶空萃取40min为异味化合物固相微萃取的最佳条件。在优化的条件下，使异味化合物吸附于纤维涂层后，将其在250℃高温下解吸，再用GC—MS分析。土腥素、β-柠檬醛、2-甲基异茨醇的检出限依次为1．0、1．3和1．7ng／L；其相对标准偏差分别为4．9％、8．4％和6．2％：3种异味化合物在5～1000ng／L的范围内线性关系良好，相关系数均大于0．997。因此，用该方法分析水中痕量（ng／L级）的异味化合物，结果满意。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.