Fe3O4/g-C3N4磁性固相萃取湖水中的3种苯甲酰脲杀虫剂

建立了Fe3O4/g-C3N4磁性固相萃取,结合高效液相色谱-可变波长紫外检测,用于测定湖水中3种苯甲酰脲杀虫剂的新方法.实验考察了溶液pH、离子强度、吸附剂用量、吸附时间、洗脱溶剂种类和体积对3种目标物回收率的影响.在最优实验条件下,氟铃脲和虱螨脲在0.50～500 ng/mL(r≥0.9997)、氟啶脲在0.20～...     

高效液相色谱-串联质谱法测定猪肉中10种苯甲酰脲类杀虫剂

建立了猪肉中除虫脲、氟幼脲、杀铃脲、氟铃脲、氟酰脲、氟苯脲、虱螨脲、啶蜱脲、氟虫脲、氟啶脲10种苯甲酰脲类杀虫剂药物残留量测定的高效液相色谱-电喷雾串联质谱方法。样品采用丙酮-正己烷提取,经中性氧化铝固相萃取柱净化,高效液相色谱-电喷雾串联质谱仪多反应监测,外标法定量和质谱确证。10种苯甲酰脲类杀虫剂在5~200μg/L范围内响应与浓度的线性关系良好,相关系数均大于0.9984;检测低限为5.0μg/kg;回收率范围为57.6%~110.0%,相对标准偏差在2.8%~12%(n=6)之间。方法满足国际上对苯甲酰脲类杀虫剂类药物最大残留限量的分析要求,已应于猪肉中苯甲酰脲类杀虫剂残留的检测。     

基质固相分散-超高效液相色谱-串联质谱法检测蔬菜中残留的苯甲酰脲类和双酰肼类杀虫剂

建立了基质固相分散技术结合超高效液相色谱-串联质谱(UPLC-MS/MS)测定蔬菜中苯甲酰脲类杀虫剂(除虫脲、灭幼脲、杀铃脲、氟苯脲、氟虫脲、氟啶脲、氟铃脲)和双酰肼类杀虫剂(甲氧虫酰肼、虫酰肼)的方法。蔬菜样品经中性氧化铝和石墨化炭黑研磨,乙酸乙酯淋洗,洗脱液浓缩定容后,经超高效液相色谱分离,分别在正、负离子多反应监测(MRM)模式下用电喷雾电离串联质谱测定,外标法定量。结果表明,9种杀虫剂在1～100 μg/L质量浓度范围内有良好的线性关系(R2≥0.99);在1、5、10、100 μg/kg 4个加标水平上的回收率为78.5%～112.8%;相对标准偏差为2.3%～10.2%,检出限为0.5～1.0 μg/kg。该方法操作简便快速,样品和溶剂用量少,检出限低,可满足蔬菜中苯甲酰脲类和双酰肼类杀虫剂同时检测的要求。     

ZIF-8@Fe_3O_4磁性固相萃取结合高效液相色谱法测定果汁中3种苯甲酰脲杀虫剂

发展了磁性沸石咪唑酯骨架材料(ZIF-8@Fe_3O_4)磁性固相萃取结合高效液相色谱-二极管阵列检测器,测定果汁中氟幼脲、四螨嗪和氟啶脲3种苯甲酰脲杀虫剂(BUs)的新方法。利用X射线衍射仪、傅立叶变换红外光谱仪、扫描电子显微镜和振动样品磁强计对合成的ZIF-8@Fe_3O_4吸附剂进行表征,考察了溶液pH值、吸附剂用量、吸附时间、洗脱溶剂种类和体积(单次洗脱体积×洗脱次数)对BUs萃取效率的影响。在最优实验条件下,氟幼脲和四螨嗪在2.0～200 ng/mL、氟啶脲在3.5～350 ng/mL范围内线性关系良好(相关系数r=0.999),检出限(S/N=3)和定量下限(S/N=10)分别为0.6～1.0 ng/mL和2.0～3.5 ng/mL。3个加标水平下的回收率为82.7%～98.6%,日内和日间(n=3)相对标准偏差(RSD)分别为1.2%～6.1%和1.3%～9.0%。当上样体积为10 mL时,ZIF-8@Fe_3O_4对果汁中3种BUs的富集倍数为43.4～48.1倍,吸附剂重复使用10次后,3种BUs回收率的RSD不大于8.8%。该方法灵敏、高效,可用于果汁样品中BUs的分析。     

聚多巴胺涂敷的聚酰胺-胺功能化二氧化硅复合材料用于水样中苯甲酰脲类杀虫剂的分散微固相萃取北大核心CSCD

近年来,由农药残留导致的环境污染问题已引起社会的广泛关注,开发便捷高效的分析方法对农药残留进行检测和监测十分必要。研究设计并成功制备了聚多巴胺涂敷的聚酰胺-胺树状分子功能化的二氧化硅复合材料(SiO-PAMAM-PDA),并采用透射电镜对其进行表征。开发了以此复合材料为吸附剂的分散微固相萃取方法(D-μ-SPE),并结合高效液相色谱对水基质中的4种苯甲酰脲类杀虫剂(BUs)残留进行了富集检测。多巴胺结构中含有丰富的苯环、氨基及羟基,可与目标物形成氢键、π-π相互作用,从而增强了材料对苯甲酰脲的萃取能力。对吸附剂用量、萃取时间等可能影响萃取效率的条件进行了单因素优化。在最优条件下,该方法的线性范围在10~500μg/L之间,根据3倍信噪比(S/N)计算所得的检出限(LOD)为1.1~2.1μg/L,回收率为82.8%~94.1%,相对标准偏差(RSD)为2.1%~8.0%。将建立的方法与已报道的以苯甲酰脲作为目标物的方法进行了对比,发现方法样品用量及萃取剂用量均较少,且所需前处理时间较短,有机溶剂消耗也较少,为苯甲酰脲类农药的检测提供了更快速、绿色的选择。为评估所开发方法的实际样品适用性,将其应用于3种河水样品中4种苯甲酰脲类杀虫剂的分析检测,所得回收率及RSD分别为69.5%~99.4%和0.2%~9.5%,表明此方法在实际样品中同样具有较高的准确性和精密度。     

MIL-53(Fe)@聚多巴胺@Fe_3O_4磁性复合材料的制备及其用于环境水样中磺酰脲类除草剂的磁固相萃取

制备了MIL-53(Fe)和聚多巴胺(PDA)修饰的磁性Fe_3O_4复合材料MIL-53(Fe)@PDA@Fe_3O_4,并将其作为吸附剂用于磁固相萃取-高效液相色谱法(MSPE-HPLC)检测环境水样中4种磺酰脲类除草剂(甲嘧磺隆、苄嘧磺隆、吡嘧磺隆和氯嘧磺隆)。实验优化了高效液相色谱条件(乙腈和含0.01%(体积分数)三氟乙酸的水溶液为流动相进行梯度洗脱,检测波长为233 nm)及磁固相萃取条件(洗脱剂为5 mL丙酮,萃取时间为4.5 min,吸附剂用量为60 mg,NaCl加入量为0.5 g,溶液pH值为3),在最佳条件下进行方法学考察,4种磺酰脲类除草剂均得到良好的线性关系,相关系数(r)≥0.998 0。方法的检出限(LOD,S/N=3)为0.28~0.77μg/L。将建立的方法用于3种环境水样中4种磺酰脲类除草剂的检测,其加标回收率为78.8%~109.7%。结果表明,制备的功能化复合材料结合了MIL-53(Fe)和Fe_3O_4的优点,可以简便快速地萃取分离环境水样中磺酰脲类除草剂。     

蔬菜中11种苯甲酰脲类农药残留的液相色谱-串联质谱法测定

建立了同时测定蔬菜中氯吡苯脲、除虫脲、灭幼脲、杀铃脲、氟铃脲、氟丙氧脲、氟苯脲、氟啶蜱脲、氟虫脲、丁醚脲、氟啶脲11种苯甲酰脲类农药残留的液相色谱-串联质谱分析方法.试样经乙腈提取,N-丙基乙二胺(PSA)和C18填料分散固相萃取净化,C18柱反相液相色谱分离,以甲醇-0.005 mol/L醋酸铵溶液为流动相梯度洗脱,电喷雾负离子模式离子化,多反应监测方式监测,三重四极杆质谱测定.结果表明:试样中添加10、20、50 μg/kg的11种苯甲酰脲类农药,回收率为69% ～109%,相对标准偏差小于16%(n=5).该方法操作简便、稳定性好、灵敏度高,检出限(LOD)为3 μg/kg,定量下限(LOQ)为10 μg/kg.     

果蔬中8种苯甲酰脲类农药残留量的液相色谱-串联质谱法测定

建立了果汁蔬菜中8种苯甲酰脲类(杀虫脲、氟苯脲、氟虫脲、氟啶脲、除虫脲、氟铃脲、灭幼脲、氟丙氧脲)农药残留量的液相色谱-电喷雾串联质谱(LC-ESI MS/MS)测定方法。样品用乙腈提取后无需净化,经盐析过滤并以水稀释(1∶1)后,经Waters Atlantis(d C18色谱柱分离,5 mmol/L乙酸铵水溶液和乙腈梯度洗脱,以电喷雾电离串联质谱在负离子多反应监测(MRM)模式下进行测定并确证,外标法定量。8种苯甲酰脲类农药在1.0~100μg/L范围内线性良好,相关系数为0.990 0~0.999 9。对8种农药在毛豆基质中3个添加水平下的回收率进行测定,平均回收率为92%~110%,相对标准偏差为5.5%~12%。方法的检出限(S/N=3)为0.04~0.42μg/kg,定量下限(S/N=10)为0.2~1.5μg/kg。     

高效液相色谱-串联质谱法测定水果中7种苯甲酰脲类杀虫药的残留量

提出了高效液相色谱-串联质谱法测定水果中7种苯甲酰脲类杀虫药(除虫脲、灭幼脲、杀铃脲、氟铃脲、氟苯脲、氟虫脲和氟啶脲)残留量的方法。该方法采用多反应监测(MRM)负离子扫描模式,可一次对水果中7种苯甲酰脲类杀虫药进行准确的定性和定量分析;样品用石油醚提取,提取液经分取、水浴45℃氮气吹干、溶解后进行分析。除虫脲、灭幼脲、杀铃脲、氟虫脲和氟啶脲的测定下限(10S/N)为2μg.kg-1,氟铃脲和氟苯脲测定下限(10S/N)为0.5μg.kg-1。7种苯甲酰脲类杀虫药在100μg.kg-1以内呈线性。方法在3个水平的加标回收率在83.8%~94.4%之间,日内相对标准偏差在3.12%~7.43%之间,日间相对标准偏差在3.96%~7.63%之间。     

蔬菜中苯甲酰脲类药物残留的测定方法研究

建立了一步有机溶剂提取、HPLC分离、紫外检测器检测7种苯甲酰脲类药物(除虫脲、灭幼脲、杀铃脲、氟铃脲、氟苯脲、氟虫脲和氟啶脲)在蔬菜中残留量的方法。考察了不同提取溶剂(乙酸乙酯和乙腈)的提取效率;研究了不同C18固相萃取小柱、活性碳、自制弗罗里硅土柱和GPC对蔬菜样品的净化效果;实验了不同的梯度淋洗程序分离7种药物。通过对黄瓜、大白菜、西红柿和包心菜4种蔬菜的4种添加水平和4次重复性实验,建立了一种以乙腈为提取溶剂和以弗罗里硅土柱为净化柱的高效液相色谱法测定7种苯甲酰脲类药物。该方法线性范围为:0.02~1.5mg/L,7种苯甲酰脲类药物的相关系数均大于0.999,其检出限为0.02~0.05mg/kg(S/N=10);在0.05~1.0mg/kg之间的添加回收率为80%~120%;相对标准偏差小于15%。方法完全符合残留分析的要求。     

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.     

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.     

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.