二氧化锡气体传感器对有机磷农药残留的动态检测

研究了一种快速检测和识别农药敌百虫、乙酰甲胺磷和乐果气体的新方法,即动态检测方法。这种方法利用单个SnO2气体传感器而非阵列在方波温度调制的状态下可实现3种农药气体的快速检测。实验结果表明：在0．02Hz的调制频率和250—300℃的温度调制范围,传感器表现出高的选择性和稳定性;利用FFT频谱和极坐标构建完成对敌百虫、乙酰甲胺磷和乐果的定性和定量检测。     

固相微萃取/二氧化锡气体传感器联用技术对果蔬中有机磷农药残留的快速检测

研究了固相微萃取(SPME)和二氧化锡气体传感器的联用技术对果蔬中有机磷农药残留乐果、氧乐果、甲胺磷、乙酰甲胺磷、马拉硫磷、敌百虫等的快速检测。结果表明，在85℃下，解吸8min，二氧化锡气体传感器在2min内完成对有机磷农药残留的快速检测。零解吸时间测量的甲胺磷的动态响应曲线表明。SPME／二氧化锡气体传感器联用技术对分析SPME的解吸平衡非常有利。     

芹菜、草莓基质对甲胺磷等4种有机磷农药测定的影响

研究芹菜、草莓基质对甲胺磷、乙酰甲胺磷、氧化乐果、毒死蜱4种有机磷农药检测的影响。利用样品基质溶液配制标准样品,对比草莓、芹菜样品、丙酮溶液中4种农药的保留时间、峰形、峰面积。结果发现DB–5MS色谱柱上,丙酮溶液、芹菜基质、草莓基质中甲胺磷、乙酰甲胺磷、氧化乐果色谱峰出峰时间不完全重合,保留时间最大漂移0.1 min。丙酮溶剂、芹菜基质较草莓基质中的甲胺磷、乙酰甲胺磷、氧化乐果更容易出现峰拖尾现象,且芹菜基质溶液中相同浓度的甲胺磷、乙酰甲胺磷峰面积分别约是草莓基质溶液中的75%,90%。毒死蜱的保留时间、峰形、响应面积在草莓基质、芹菜基质、丙酮溶液中基本一样。     

高效液相色谱-串联质谱法测定烟草中有机磷农药的残留量

建立了一种基于液相色谱-串联质谱法(LC-MS/MS)定量分析微量有机磷农药残留的方法,并应用于烟草中农药残留物的定量检测。采用乙腈超声提取烟草中的有机磷农药残留,以甲醇-水（含0.1%乙酸铵）(体积比为95∶5)为流动相,经高效液相色谱分离,以串联质谱在多反应监测(MRM)模式下测定,在2.5 min内完成了甲胺磷、乙酰甲胺磷、乐果、敌百虫、毒死蜱5种常用有机磷农药的定量分析。5种农药在1~200 μg/L内的线性关系良好(r>0.998),平均回收率为77%~104%,检出限为1.0~5.0 μg/kg。     

无氧条件~(60)Co-γ辐射降解乙酰甲胺磷的研究

利用60Co-γ辐射降解无氧条件有机磷农药乙酰甲胺磷(Acephate)的稀水溶液,研究了不同吸收剂量下的乙酰甲胺磷稀水溶液辐照前后的毒性变化;采用高效液相色谱(HPLC)和离子色谱(IC)对降解产物进行了分析。结合溶液毒性、降解率和生成的无机离子浓度变化等,比较了两种无氧气氛的降解效果。     

L-古洛糖酸γ-内酯对蔬菜中有机磷农药残留测定基质效应的补偿作用研究

建立了一种采用掩蔽试剂对有机磷农药残留测定时的基质效应进行补偿的方法.研究了其对仪器稳定性、耐受性的影响及对基质效应的补偿效果.结果显示,1.0 g/L的L-古洛糖酸γ-内酯对敏感农药甲胺磷、乙酰甲胺磷、氧乐果和久效磷的色谱行为改善显著,响应值分别提高了2.8、9.1、10.4和4.8倍,未对非敏感农药测定产生负面影响...     

液相色谱-串联质谱法测定水产品中7种有机磷类农药残留物

使用高效液相色谱-串联质谱仪(LC-MS/MS)同时测定水产品中的敌百虫(Dipterex)、敌敌畏(Dichlorvos)、蝇毒磷(Coumaphos)、乙酰甲胺磷(Acephote)、甲胺磷(Methamidophos)、毒死蜱(Chlorpyrifos)、乐果(Dimethoate)等7种有机磷类药物的残留量.采用酸化的乙酸乙酯提取均质后的样品,提取液过酸性氧化铝柱净化去脂,经(LC/MS/MS)电喷雾电离(ESI)源,正离子多反应检测(MRM)模式检测,外标法定量.敌百虫、敌敌畏、蝇毒磷、乙酰甲胺磷、甲胺磷、毒死蜱、乐果检出限均可达到10 μg/kg,在添加浓度10～200 μg/kg之间线性关系良好,相关系数(r)均>0.9990,对于10、15、20 μg/kg水平添加回收率范围在72.9%～106%之间,相对标准偏差(RSDs)范围在1.89%～11.6%之间.     

茶叶中乙酰甲胺磷及甲胺磷对映体的气相色谱法分离与测定

建立了乙酰甲胺磷、甲胺磷对映体在茶叶基质中的手性拆分与定量方法。比较了2种手性柱对乙酰甲胺磷及甲胺磷对映体的分离效果,并对分离效果较优的BGB-176手性柱进行色谱条件优化。茶叶样品经改良QuEChERS法处理后,气相色谱测定,外标法定量。在0.04,0.08,0.4 mg/kg 3个加标水平下,甲胺磷、乙酰甲胺磷的回收率分别为58.3%~66.4%和50.8%~57.6%,相对标准偏差(n=5)均小于7%。方法检出限为0.003~0.01 mg/kg。该方法简便、可靠,满足分析要求。通过实际样品的检测,发现乙酰甲胺磷、甲胺磷对映体在茶树上存在一定的降解差异。     

基于CdSe/ZnS量子点构建乙酰甲胺磷荧光检测方法研究

本文以CdSe/ZnS量子点为荧光探针,基于乙酰甲胺磷对CdSe/ZnS量子点的荧光猝灭效应,建立了一种可快速测定乙酰甲胺磷的荧光检测方法。通过透射电子显微镜(TEM)、紫外-可见吸收光谱和荧光光谱对CdSe/ZnS量子点进行表征。在反应时间为5 min条件下,乙酰甲胺磷的浓度在0.487×10~(-6)～7.225×10~(-6) mol/L范围内与CdSe/ZnS量子点的荧光猝灭强度比值呈良好的线性关系(R~2=0.9987),方法检出限为2.55×10~(-7) mol/L。在2.0、5.0μmol/L加标水平下的回收率为94.5%～102.8%,相对标准偏差(RSD,n=5)小于4%。该方法选择性好,灵敏度高,可用于水果和蔬菜中农药乙酰甲胺磷的快速检测。     

基于大肠杆菌的全细胞微生物传感器的构建及其在急性生物毒性检测中的应用

构建了以大肠杆菌为指示生物的全细胞微生物传感器,初步探讨了其在重金属(Cu2+,Zn2+,Pb2+)及其二元联合毒物、农药污染物(莠灭净、乙酰甲胺磷)的急性生物毒性分析中的应用性能。结果表明,基于对数生长后期和稳定期的大肠杆菌微生物传感器具有良好的毒性分析性能。最优实验条件为:E.coli培养16 h,苯醌为电子传递介体,呼吸基质pH 6～8。所测毒物对E.coli的呼吸抑制作用大小顺序为:Cu2+>Zn2+>Pb2+,乙酰甲胺磷>莠灭净,与发光细菌、鱼类、藻类等其它方法检测所得结果一致。这种电化学全细胞生物传感器毒性分析方法具有快速灵敏、成本低廉、操作简单等优点,有望用于水体急性生物毒性的在线监测。     

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.