微波辅助萃取/气相-质谱联用分析蔬菜中的有机磷农药

 建立了微波辅助萃取 (MAE) /气相 质谱联用法 (GC MS)测定蔬菜样品中二嗪磷、对硫磷、水胺硫磷的分析方法 ,研究了不同溶剂的萃取效率。选择二氯甲烷为萃取溶剂 ,采用二因素三水平的正交设计实验优化了萃取溶剂体积和萃取时间。方法的线性范围分别为二嗪磷和对硫磷 4ng/ g～ 40 0ng/ g、水胺硫磷 2 0ng/ g～ 40 0ng/ g,检出限分别为二嗪磷 0 2 9ng/g、对硫磷 1 70ng/g、水胺硫磷 2 30ng/g。测定 2 0 0 0ng/g和 50 0ng/g加标蔬菜样品 ,回收率为 72 2 %～ 1 0 2 0 % ,RSD为 1 5 %～ 1 1 0 %。。     

动态液相微萃取-气相色谱法测定水样中残留有机磷农药

应用动态液相微萃取与气相色谱联用技术测定了水样中3种有机磷农药(敌敌畏、甲基对硫磷、对硫磷).考察了萃取溶剂、溶剂体积、萃取次数、水样pH值以及离子强度对液相微萃取的影响.该方法甲基对硫磷、对硫磷的线性范围在30～70μg·L-1之间,敌敌畏的线性范围在40～70μg·L-1之间,回收率在84.9%～103.0%之间,相对标准偏差(n=7)在5.1%～9.4%之间,检出限(3S/N)为26.5～35.7μg·L-1.     

固相微萃取与气相色谱-质谱联用测定有机磷杀虫剂的残留量

建立了固相微萃取与气相色谱-质谱(SPME-GC/MS)联用测定水样中有机磷杀虫剂残留量的方法。探讨了影响SPME萃取效果的萃取头类型萃取时间 解吸时间 离子强度等诸因素,优化了GC-MS仪器条件。在优化的GC-MS条件下, 杀虫剂的响应值与浓度有良好的线性关系, 检出限分别为敌敌畏0.40 μg/L 甲基对硫磷0.01 μg/L 马拉硫磷0.025 μg/L 对硫磷0.004 μg/L。方法用于实际水样分析,结果令人满意,样品的加标回收率为94.7%-110.0%。该方法具有分析速度快 灵敏     

固相微萃取-高效液相联用分析环境水样中的痕量■

 应用固相微萃取与高效液相联用技术 (SPME HPLC)分析了环境水样中的痕量 艹屈 。对SPME的条件如萃取时间、萃取温度、离子强度、解吸方式、解吸溶剂、解吸时间和HPLC条件进行了优化 ,建立了SPME HPLC分析环境水样中痕量 艹屈 的方法 ,并将其用于分析自来水、雨水、矿泉水和江水等实际水样。方法的线性范围为 0 0 13μg/L～ 3 0 μg/L ,检出限为 2 7ng/L ,相对标准偏差 (RSD ,n =6 )为 5 6 % ,回收率为 10 3 2 %～ 119 3%。该方法适合于环境水样中痕量 艹屈 的分析 ,体现了SPME在样品前处理中快速、灵敏、简单、无溶剂的特点。     

气相色谱-火焰光度法测定土壤中有机磷农药残留

建立了气相色谱-火焰光度(GC-FPD)分析土壤中敌敌畏、氧化乐果、二嗪农、乐果、甲基对硫磷、马拉硫磷、对硫磷、水胺硫磷、喹硫磷等9种有机磷农药残留量的方法。样品用丙酮-二氯甲烷(1:3)提取,浓缩、定容后用Hp-5MS(30m×0.25 mm×0.25μm)毛细管柱分离,FPD检测器检测。方法回收率在68.71%～110.39%之间;RSD在5.5%～11%之间;检出限在0.397～1.60μg/mL之间,方法可用于环境土壤样品中有机磷农药残留的测定。     

微波辅助萃取/气相色谱-质谱联用分析蔬菜中的有机磷农药

建立了微波辅助萃取（MAE）/气相色谱-质谱联用法（GC-MS）测定蔬菜样品中二嗪磷、水胺硫磷的分析方法，研究了不同溶剂的萃取效率。选择二氯甲烷为萃取溶剂，采用二因素三水平的正交设计实验优化了萃取溶剂体积和萃取时间。方法的线性范围分别为二嗪磷和对硫磷4ng/g-400ng/g，水胺硫磷20ng/g-400ng/g，检出限分别为二嗪磷和对硫磷4ng/g-400ng/g、水胺硫磷20ng/g-400ng/g，检出限分别为二嗪磷0.29ng/g、对硫磷1.70ng/g、水胺硫磷2.30ng/g。测定200.0ng/g和50.0ng/g加标蔬菜样品，回收率为72.2%-102.0%,RSD为1.5%-11.0%。与传统的机械振荡萃取法相比，不仅萃取效率相当，而且还具有省时省溶剂的优点。     

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.     

固相微萃取-高效液相色谱法测定垃圾渗滤液中的双酚A

本文应用固相微萃取一高效液相色谱法(SPME—HPLC)分析了垃圾渗滤液中的痕量双酚A。对SPME的条件如测定模式、pH值、萃取时间、解吸方式、解吸溶剂、解吸时间和HPLC条件进行了优化。建立了SPME—HPLC分析垃圾渗滤液中痕量双酚A的方法。方法的线性范围为12．8～192μg／L,相关系数为0．9975,检出限为3．25μg／L(3σ,n=11)。以12．8μg／L的双酚A标准溶液平行测定11次,相对标准偏差(RSD)为4．4％,回收率为94．5％～103．3％。将其用于分析具有垃圾填埋场的渗滤液实际水样,结果十分满意。该方法具有快速、灵敏、简单、无溶剂的特点,适合于环境水样中痕量双酚A的分析。     

固相微萃取-高效液相色谱联用测定水样中的痕量苯并(k)荧蒽

研究了固相微萃取(SPME)-高效液相色谱(HPLC)联用测定水样中痕量苯并(k)荧蒽的的分析方法。对SPME的条件如萃取时间、萃取温度、离子强度、解吸方式、解吸溶剂、解吸时间和HPLC条件进行了优化，建立了SPME-HPLC联用分析水样中痕量苯并(k)荧蒽的方法，并用于自来水、雨水和纯净水等实际水样的分析。SPME优化的条件为室温、搅拌速度1100r／min、萃取时间30min、甲醇解吸溶剂、解吸时间2min。HPLC的条件为C18反相色谱柱、甲醇流动相、流速1mL/min、紫外检测器、波长244nm，以峰高为测量信号。方法的线性范围为0～8．00μg／L，检出限为0．014μg／L，相对标准偏差(n=6)为6．7％，回收率为82．0％～104．2％。该方法适合于水样中痕量苯并(k)荧蒽的分析。     

浊点萃取-气相色谱法同时测定6种有机磷农药

建立了浊点萃取-气相色谱法同时测定6种有机磷农药(OPPs)的分析方法。以聚乙二醇6000为萃取剂,乙酸乙酯和正己烷混合液(65∶35)作为反萃取剂,兼顾不同极性OPPs的萃取,并解决了表面活性剂因沸点高、粘度大无法进入气相检测的问题。在最佳条件下,6种OPPs在2.5～8 000μg/L范围与峰面积呈现良好的线性关系(r~2≥0.9958),检出限在0.8～5.0μg/L范围内,相对标准偏差(RSD)5.18%(n=6)。该方法成功应用于测定环境水样和土壤中的6种OPPs,加标回收率为89.7%～109.9%。     

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.     

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.     

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.     

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.     

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.     

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.     

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.