Determination of 29 pesticide residues in tobacco by gas chromatography-electron impact ionization mass spectrometry

开展了卷烟和烟叶中有机氯、有机磷和拟除虫菊酯3类29种农药残留的气相色谱-电子轰击离子源质谱(gC-EI/MS)的分析方法研究。优化与选择了卷烟和烟叶样品的前处理条件,样品经正己烷-丙酮(体积比为1∶1)混合提取剂超声提取、flOrISIl硅土和中性氧化铝双净化剂固相萃取柱净化、二氯甲烷-正己烷(体积比为95∶5)混合洗脱剂洗脱和浓缩后,以磷酸三苯酯(TPP)为内标物,采用gC-EI/MS的选择离子监测方式(SIM)进行定性和定量分析。当样品的加标水平为20,50,100μg/kg时,加标回收率为70%--110%,相对标准偏差在2%--8%之间;除了甲氰菊酯、氯菊酯和溴氰菊酯的方法检出限(lOd)分别为1.85,1.74与2.54μg/kg外,其余的26种农药的lOd均小于0.8μg/kg;线性范围为5.0--500.0μg/kg,相关系数都大于等于0.999 4。此分析方法已成功地应用于卷烟和烟叶样品中3类29种痕量农药残留的分析。A method was developed for rapid determination of 29 pesticide residues in tobacco based on gas chromatography coupled with electron impact ionization mass spectrometric detection(GC-EI/MS).After the optimization of different parameters,such as the extraction solvent,elution solvent,purificant,pesticides were extracted from tobacco with hexane-acetone(1∶1,v/v) in an ultrasonic bath,cleaned-up on a column,packed with Florisil and neutral alumina,eluted with dichloromethane-hexane(95∶5,v/v),and then determined by GC-EI/MS in the selected ion monitoring mode(SIM) with triphenyl phosphate(TPP) as internal standard.The recoveries were performed at 20,50 and 100 μg/kg fortification levels for each pesticide,and the recoveries ranged from 70% to 110% with the relative standard deviations between 2% and 8%.The detection limits were less than 0.8 μg/kg for 26 pesticides except for the fenpropathrin,deltamethrin and permethrin.The method was linear over the range of 5.0-500.0 μg/kg with the correlation coefficients between 0.9994 to 0.9999.The method was successfully applied to the analysis of these pesticides in tobacco.国家基础科学人才培养基金项目(J0630429

仪器分析实验课程对拔尖人才培养的探讨与思考

以"拔尖班"实验教学为例,阐述了仪器分析实验课程如何实行多元化教学。仪器分析实验利用网络教学平台,实现了师生跨时间、空间的交流,通过开展拓展性实验,强化了"拔尖班"学生的探究与创新性思维体验。同时对"拔尖班"人才培养中存在的一些问题进行了探讨。国家基础科学人才培养基金(J1310024)2016年福建省本科高校教育教学改革研究项目(生物工程专业实验精品资源共享课建设项目)2017年福建省本科高校教育教学改革研究项目(FBJG20170277

Determination of 19 Organophosphorous Pesticides Residues in Milk Drink and Milk Powder by Gas Chromatography-Negative Chemical Ionization-Mass Spectrometry

将气相色谱-负离子化学源质谱法(GC-NCIMS)应用于牛奶饮品和奶粉中19种有机磷农药残留的同时分析。牛奶饮品和奶粉经乙腈提取剂超声提取、Florisil硅藻土和中性氧化铝双净化剂同时净化及正己烷-乙酸乙酯(体积比1∶1)混合洗脱剂洗脱后,以三苯基磷酸酯为内标物,采用GC-NCI MS的选择离子监测方式(SIM)定性与定量分析。当牛奶饮品和奶粉的加标浓度水平为20、100、500μg/kg时,平均加标回收率为64.5%~129%,相对标准偏差为2%~20%;除喹硫磷的方法检出限(MDL)为2.4μg/kg外,其余18种有机磷农药的MDL均小于1.0μg/kg;线性范围为10~500μg/kg,相关系数均大于0.9988,此分析方法成功地应用于牛奶饮品和奶粉中多种痕量有机磷农药残留的分析。A rapid method was developed for the determination of 19 organophosphorous pesticides residues in commercial milk drink and milk powder.Under optimized conditions,the pesticides were extracted from milk drink or milk powder with acetonitrile in an ultrasonic bath and cleaned up on a Florisil and neutral alumina column,and were determined by gas chromatography with negative chemical ionization mass spectrometric detection in the selected ion monitoring mode with triphenyl phosphate as internal standard.The recoveries for all the pesticides studied ranged from 64.5% to 129% with a relative standard deviation range of 2%-20%.The detection limit of the method was less than 1.0 μg/kg for most of the pesticides except for the quinolphos.The linear ranges of the calibration curves ranged from 10 μg/kg to 500 μg/kg with correlation coefficients of 0.998 8.The proposed method was successfully applied to the analysis of these compounds in milk drink and milk powder

Multiresidue Determination of Organophosphorus Pesticide Residues in Vegetables and Fruit by Gas Chromatography-Negative Ion Chemical Ionization-Mass Spectrometry

将气相色谱-负离子化学电离质谱法(GC-NC I-M S)应用于蔬菜水果中9种有机磷农药残留的分析测定,初步解析了这些农药的NC I-M S特征阴离子结构和断裂机理,并初步探讨了GC-NC I-M S分析蔬菜水果中有机磷农药残留时基体效应的影响。采用空白样品基体匹配校准曲线法(M C)进行定量分析,有效地降低了基体效应的影响。蔬菜水果样品用乙酸乙酯超声提取,以乙硫磷为内标物,采用GC-NC I-M S的选择离子监测方式(S IM)进行定性和定量分析。9种有机磷农药的方法检测限为0.12~1.0μg/kg。在方法的检测限与1 000μg/kg范围内,线性相关系数都大于0.999 3。当空白蔬菜水果(西红柿)样品的加标水平为100,400,800μg/kg时,平均加标回收率为78%~126%,相对标准偏差为0.58%~14.7%。An analytical method of gas chromatography coupled with negative ion chemical ionization-mass spectrometry for simultaneous determination of nine organophosphorus pesticide residues in vegetables and fruit has been developed,and the negative ions structure and partition mechanism of the nine organophosphorus pesticides were interpreted.Meanwhile,the matrix effect for sample analysis was discussed,and matrix-matched calibration for quantification was introduced to reduce the matrix effect in this method.Pesticides were extracted from sample with ethyl acetate in an ultrasonic bath,then determined by gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode,and ethion was used as an internal standard.The detection limits of the method were 0.12-1.0 μg/kg for the nine organophosphorus pesticides,and the relative coefficients were higher than(0.9993).A blank sample(tomato) was spiked at 100,400,800 μg/kg for each pesticide,and the recoveries were determined to be from 78% to 126% with relative standard deviations from 0.58% to 14.7% for the pesticides

Determination of Multiple Pesticide Residues in Honey Using Gas Chromatography-Mass Spectrometry

开展了蜂蜜中23种农药残留的气相色谱-电子轰击离子源质谱(GC-E I/M S)分析方法的研究,并对其中3种农药的E I/M S碎片离子的断裂机理与结构进行了初步解析。探讨了蜂蜜试样前处理条件的优化与选择。将蜂蜜试样用乙酸乙酯提取剂超声提取、F lo ris il硅藻土色谱柱净化和正己烷-乙酸乙酯(体积比为7∶3)混合洗脱剂洗脱后,以PCB103为内标物,采用选择离子监测(S IM)方式下的GC-E I/M S分析。当试样的加标浓度为50,100和200μg/kg时,加标回收率为82%~120%,相对标准偏差小于11.0%。23种农药的检测限都小于10.0μg/kg,线性范围为10~500μg/kg,相关系数都大于0.995。此分析方法已成功地应用于蜂蜜中23种痕量农药残留的分析。An analytical method was developed for the simultaneous determination of 23 pesticide residues in various commercial honeys.Meanwhile,the characteristic ions and fragmentation mechanism of three pesticides in the process of electron ionization mass spectrometry(EI/MS) were evaluated.After the optimization of different parameters such as the extraction solvent,pesticides were extracted from honey with ethyl acetate in an ultrasonic bath,cleaned up on a Florisil column by an elution of mixture of hexane and ethyl acetate(7∶ 3,v/v), and analyzed by gas chromatography-electron ionization mass spectrometry(GCEI/MS) in the selected ion monitoring mode(SIM) with PCB103 as internal standard.Recovery studies were performed at 50,100 and 200 μg/kg fortification levels for each pesticide,and the recoveries ranged from 82% to 120% with relative standard deviations between 1.8% and 11.0% for different pesticides.The limit of detection was less than 10.0 μg/kg for all the pesticides.The developed method was linear in the range of 10-500 μg/kg,with correlation coefficients larger than 0.995.Finally,the developed analytical method has been successfully applied to the determination of pesticide residues in several honey samples

Determination of Five Polybrominated Diphenyl Ether Residues in Deep-Sea Fish Oil Using Gas Chromatography-Negative Chemical Ionization/Mass Spectrometry

建立了气相色谱-负离子化学电离质谱法(GC-NCI/MS)同时分析深海鱼油食品中5种多溴联苯醚残留的分析方法。深海鱼油食品用正己烷超声提取、中性与酸性硅胶色谱柱净化和正己烷洗脱后,以PCB103为内标物,采用GC-NCI/MS的选择离子监测方式(SIM)分析;同时探讨了5种多溴联苯醚的NCI/MS特征离子的断裂机理。当空白深海鱼油食品的加标浓度为20.0和100.0μg/kg时,加标回收率为88.6%-111.3%,相对标准偏差为3.8%-13.5%,方法的检测限为0.77-1.34μg/kg,线性范围为1.0-500.0μg/kg,相关系数均大于0.999 2。此方法已成功地应用于深海鱼油食品中5种痕量多溴联苯醚残留的同时分析。Polybrominated diphenyl ethers(PBDEs) are a kind of brominated flame retardants(BFRs),which refer to compounds used in some plastics to impede or even suppress the combustion process.As the emission or disposal of plastics,PBDE residues have been found in both environment and biota.In this work,an analytical method was developed for the simultaneous determination of 5 PBDE residues in deep-sea fish oil.PBDEs were extracted from deep-sea fish oil with n-hexane,cleaned up on a silical gel column,and determined by using gas chromatography-negative chemical ionization/mass spectrometry(GC-NCI/MS) in the selected ion-monitoring(SIM) mode,with PCB103 as the internal standard.Meanwhile,the characteristic ion and fragmentation mechanism of some PBDEs in NCI/MS were evaluated.Recovery studies were performed at 20.0 and 100.0 μg/kg fortification levels for each PBDE,and the recoveries ranged from 88.6% to 111.3% with relative standard deviations between 3.8% and 13.5% for different PBDEs.The limits of detection(LOD) were from 0.77 to 1.34 μg/kg for different PBDEs.The developed method was linear over the range assayed,1.0-500.0 μg/kg,with correlation coefficients larger than 0.999 2.The developed method has also been successfully applied to the determination of PBDEs in several deep-sea fish oil samples and the three most abundant PBDEs(PBDE-47,PBDE-99 and PBDE-100) were found

Electric-field-induced selective catalysis of single-molecule reaction

随着单分子电学检测技术的迅速发展，分子电子学的研究不再局限于分子电子学器件的构筑及其电学性质的测量，而且扩展到单分子尺度化学反应过程的探索。然而目前相关的研究仍然局限于理论计算方面，在单分子尺度上实时监测和调控化学反应的活性和选择性是化学领域的长期目标和挑战。针对这一挑战，洪文晶教授课题组与程俊教授课题组合作，自主研发了精密科学仪器，将单个有机分子定向连接在两个末端尺寸为原子级的电极之间，解决了化学反应中分子取向控制的问题.理论计算结果证实了定向电场可以有效地稳定化学反应的过渡态，从而降低反应能垒。该研究工作在化学化工学院洪文晶教授、程俊教授、能源材料化学协同创新中心（iChEM）刘俊扬副研究员的共同指导下完成，由硕士研究生黄晓艳、iChEM博士研究生唐淳、博士研究生李洁琼以及兰州大学的陈力川博士作为共同第一作者，化学化工学院师佳副教授、陈招斌高级工程师、夏海平教授和田中群教授，萨本栋微纳研究院杨扬副教授、环境与生态学院白敏冬教授以及兰州大学张浩力教授参与了研究工作的讨论并给予指导，博士后乐家波、博士研究生郑珏婷、张佩（已毕业）、李瑞豪、李晓慧也参与了研究工作。Oriented external electric fields (OEEFs) offer a unique chance to tune catalytic selectivity by orienting the alignment of the electric field along the axis of the activated bond for a specific chemical reaction; however, they remain a key experimental challenge. Here, we experimentally and theoretically investigated the OEEF-induced selective catalysis in a two-step cascade reaction of the Diels-Alder addition followed by an aromatization process. Characterized by the mechanically controllable break junction (MCBJ) technique in the nanogap and confirmed by nuclear magnetic resonance (NMR) in bottles, OEEFs are found to selectively catalyze the aromatization reaction by one order of magnitude owing to the alignment of the electric field on the reaction axis. Meanwhile, the Diels-Alder reaction remained unchanged since its reaction axis is orthogonal to the electric fields. This orientation-selective catalytic effect of OEEFs reveals that chemical reactions can be selectively manipulated through the elegant alignment between the electric fields and the reaction axis.This work was supported by the National Key R&D Program of China (2017YFA0204902), the National Natural Science Foundation of China (21722305, 21703188, 21673195, 21621091, 51733004, 51525303, and 91745103), the China Postdoctoral Science Foundation (2017M622060), and the Young Thousand Talents Project of China. 该工作得到国家自然科学基金委（21722305、21703188、21673195、51733004、51525303、91745103），国家重点研发计划课题（2017YFA0204902），中国博士后面上基金（2017M622060）的资助，以及固体表面物理化学国家重点实验室、醇醚酯化工清洁生产国家工程实验室、能源材料化学协同创新中心的支持

Single-Molecule Plasmonic Optical Trapping

人们对于在常温常压条件下尤其是溶液环境中俘获或者操控微观粒子的追求从未停止，以期不断减少可操控的微观粒子的尺寸，最终实现单分子操控的目标。化学化工学院田中群教授和洪文晶教授团队合作，利用等离激元光学纳米间隙实现单分子的直接捕获与释放。该工作由化学化工学院田中群教授、洪文晶教授以及萨本栋微米纳米科学技术研究院杨扬副教授共同指导，由化学化工学院已毕业博士生战超提出思路并设计实验、与萨本栋微米纳米研究院已毕业硕士生王干共同完成主要实验工作，已毕业博士生易骏完成理论模拟工作。魏珺颖硕士、博士生李之豪、陈招斌高工和师佳副教授参与了部分研究和课题讨论。【Abstract】The volume of the object that can be manipulated in solution is continuously decreasing toward an ultimate goal of a single molecule. However, Brownian motions suppress the molecular trapping. To date, free-molecule trapping in solution has not been accomplished. Here, we develop a strategy to directly trap, investigate, and release single molecules (∼2 nm) in solution by using an adjustable plasmonic optical nanogap, which has been further applied for selective single-molecule trapping. Comprehensive experiments and theoretical simulations demonstrated that the trapping force originated from plasmonic nanomaterials. This technique opens an avenue to manipulate single molecules and other objects in the size range of primary interest for physics, chemistry, and life and material sciences without the limitations of strong bonding group, ultra-high vacuum, and ultra-low temperature, and makes possible controllable single-molecule manipulation and investigation as well as bottom-up construction of nanodevices and molecular machines.This work is financially supported by the National Natural Science Foundation of China (21533006, 21621091, 21673195, 21973079, and 21722305), and the National Key R&D Program (2017YFA0204902, 2015CB932300). 该工作得到国家自然科学基金、国家重点研发计划课题的资助，以及固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Multiresidue determination of polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) in egg samples by gas chromatography-mass spectrometry

建立了气相色谱-负离子化学源-质谱法(gC-nCI-MS)同时分析禽蛋食品中10种多溴联苯(PbbS)和多溴联苯醚(PbdES)残留的分析方法。禽蛋食品用正己烷超声提取、浓硫酸酸化、中性和酸性硅胶层析柱净化和正己烷洗脱后,以PCb209为内标物,采用gC-nCI-MS的选择离子监测方式(SIM)分析;同时探讨了目标物PbdE100 nCI-MS特征离子的断裂机理。当禽蛋食品空白的加标质量浓度为5(3.5)和50(35)μg/kg时,加标回收率为75.2%~107%,相对标准偏差为2.3%~8.8%,方法检测限为0.14~0.39μg/kg,线性范围为1~250μg/kg,相关系数皆大于0.9991,方法已用于禽蛋食品中10种痕量PPbS和PbdES残留的同时分析。A method for the simultaneous determination of 10 PBBs and PBDEs in egg samples was developed.PBBs and PBDEs were extracted from egg samples with hexane and cleaned up on an acid silica gel column,then were determined by using gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode,and with PCB209 as internal standard.Meanwhile,fragmentation mechanism of PBDE100 negative chemical ionization mass spectrometry was evaluated.Recovery studies were performed at 5(3.5) and 50(35) μg/kg fortification levels for each PBDEs(PBBs),and the recoveries ranged from 75.2% to 107% with relative standard deviations between 2.3% and 8.8% for the different PBDEs and PBBs.The developed method was linear over the range of 1～250 μg/kg,with correlation coefficients more than 0.9991.Finally,the developed analytical method has been applied to the determination of PBDEs and PBBs in several egg samples.国家基础科学人才培养基金(J0630429)项目资

Multiresidue Determination of 17 Organochlorine and Pyrethroid Pesticides in Tea by Gas Chromatography-Negative Chemical Ionization-Mass Spectrometry

建立了茶叶试样中17种农药残留(8种有机氯和9种拟除虫菊酯农药)的气相色谱-负化学离子源-质谱(GC-NC I-MS)联用的分析方法.茶叶试样用V(正己烷)/V(丙酮)=1/1混合提取剂超声提取,经F lorisil硅藻土和中性氧化铝混合层析柱净化后,以环氧七氯为内标物,采用GC-NC I-MS的选择离子监测方式(SIM)分析;探讨了茶叶试样的基体诱导色谱响应增强影响所产生的分析误差及其减小的措施,用空白试样基体匹配校准曲线法(MC法)定量分析.当加标质量浓度水平为20,50和200μg/kg时,加标回收率为67.9%~129%,相对标准偏差为1.0%~20%,除氯菊酯农药的检出限为8.3μg/kg外,其余大部分农药的检出限均小于1.0μg/kg,线性范围为10~500μg/kg,相关系数均大于0.996,此方法成功地应用于茶叶试样中痕量农药残留的分析.An analytical multiresidue method for the simultaneous determination of 17 pesticides(8 organochlorines and 9 pyrethroids) in tea was developed.Pesticides were extracted from tea with hexane-acetone(volume ratio is 1∶1) in an ultrasonic bath and cleaned up on a Florisil and neutral alumina column, then were determined by gas chromatography with negative chemical ionization mass spectrometric detection in the selected ion monitoring mode,and with heptachlor epoxide as the internal standard.Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination.The recovery studies were performed at 20,50 and 200 μg/kg fortification levels for each pesticide,and the recoveries ranged from 67.9% to 129% with a relative standard deviation between 1.0% and 20% for the different pesticides. The detection limit of the method was less than 1.0 μg/kg for most of pesticides except for the permethrin.The developed method was linear over the range assayed,10-500 μg/L,with determination coefficients>0.996.Finally,the developed analytical method was successfully applied to the determination of pesticides in several tea samples