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

继往开来,任重道远--纪念中国半导体事业五十周年

今年是中国半导体事业五十周年.其实谁也没有这么规定过,也没有任何文件中提到.事实上,中国的半导体事业从新中国一成立就开始进行,那为什么将1956年作为中国半导体事业的开始?中文核心期刊要目总览(PKU)中国科学引文数据库(CSCD)012987-9903

FORMATION AND OPTICAL EXCITATION MECHANISM of Er LUMINESCENCE CENTERS IN RARE EARTH Er-LMPLANTED InP

用离子注人法对InP晶体实现高浓度稀土（rE）Er的掺杂，探索了优质材料的制作规律和条件。在低温（10~200k）测量了光致发光谱（Pl），观测到Er的尖锐发光峰，其峰值波长1.538μM，其发光强度较大；研究了该材料的热退火行为，Er发光中心的形成和光激活过程；用ruTHErfOrd背散射谱（rbS）测量给出了热退火前后注Er-InP晶体中Er离子浓度的数值及深度分布；并对Er发光中心的组成和光激发机制作了分析讨论。The rare earth doped Ⅲ - Ⅴ compound luminescence material InP: Er was prepared by ion implantation method.The photoluminescence spectra(PL) of the samples were measured at low temperature (10-200K ).The sharp luminescence peak (wavelength 1.538μm) of Er centers has been observed.The Er concentration profiles were measured by RutherFord back-scattering spectrometry (RBS) in Er-implanted Inp crystals.The Formation and optical excitation mechanism of Er luminescence centers in the samples were analysed.国家自然科学基金;北京大学稀土材料化学及应用国家重点实验室资

SECONDARY ION MASS SPECTROMETRY STUDIES of ERBIUM IMPLANTED IN SEMICONDUCTORS GaP,GaAs AND InP

近年来掺稀土元素的Ⅲ—V族化合物研究在基础物理和器件应用方面都越来越引起人们的关注,其中又由于Er-(3+)的-4I_(13/2)—4-I——(15/2)的特征发光波长为1.54μM,恰好对应于石英光纤的低损耗区,且离子注入技术简单易行,因而倍受重视.国际上已报道了不少有关Er注入Ⅲ—V族化合物的研究,大多选用较低的注入剂量(约10-(12)~10-(14)Er/CM-2),而对较高剂量的注入有待于进一步研究.Er ions were implanted in II-V compounds semiconductors GaP,GaAs and InP with relatively high dosages 5X1014/cm2 at 150keV and 350keV,respectively.Secondary Ion Mass Spectrpmetry(SIMS)depth profiles were carried out on a Cameca IMS4F ionmi-croprobe using a 600nA,15keV O2+ primary beam,rastered by 400mX400m over the sample.A mechanical aperture was employed to select positive secondary ions From the central portion of the crater(-60m in diameter).The crater total depth was measured using a profilometer.Depth profiles have been obtained and the peak depths in GaP, GaAs,InP are 55nm,51nm,56nm and 85nm,83nm,80nm at 150keV and 350keV,respectively.The sharp photoluminescence (PL)spectra have been observed at 1.538m, which correspond to the transition From the First state 4I13/2 to the ground state 4I15/2 of Er3+ aFter Face to Face annealing.国家自然科学基金资助项

SECONDARY ION MASS SPECTROMETRY of ERBIUM AND OXYGEN CO IMPLANTED IN GaAs

在Ⅲ-V族半导体gAAS外延层上共注入Er和O离子（gAAS：Er，O）.经面对面优化退火后，光致发光（PHOTOluMInESCEnCE-Pl）谱中观测到对应Er3＋第一激发态到基态4I13/2-4I15/2跃迁，其相对强度较单注入Er的gAAS（gAAS：Er）增强10倍，且谱线变窄.从二次离子质谱（SECOndAryIOnMASSPECTrOMETry-SIMS）和卢瑟福背散射实验给出退火前后Er在gAAS：Er样品中的剖面分布.SIMS测量分别给出O注入前后Er和O在gAAS：Er，O中的深度剖面分布，分析表明Er和O共注入后形成光学激活有效的发光中心.Er and O ions were co implanted in Ⅲ Ⅴ compound semiconductor GaAs (GaAs:Er,O).AFter Face to Face annealing the sharp photoluminescence (PL) spectra were observed at 1.538μm, which correspond to the transition From the First excited state 4I 13/2 to the ground state 4I 15/2 of Er 3+ .The intensity of PL was enhanced about ten times in comparison with the only Er implanted GaAs sample: GaAs:Er. Depth profiles of Er implanted concentration were obtained and analyzed by Secondary Ion Mass Spectrometry(SIMS) and RutherFord Back Scattering(RBS) measurements as implanted and annealed.Depth profiles of Er and O co implanted were analyzed and studied by SIMS.The results indicate that a kind of optically active eFFicient luminescence center is Formed in GaAs:Er,O.国家自然科学基金;北京大学稀土材料化学应用国家重点实验室基

中西科学传统的比较研究(笔谈)

由于中西自然环境以及经济、政治、文化等社会历史背景的不同 ,中西科技传统有着本质性的差异。由于这种差异的深刻影响 ,造成近代科学没有在中国产生 ,也使当前科学在面临大量复杂性现象时有着巨大的困惑。对中华科学传统的某种回归 ,实现东西文化的结合已成为当代国内外学术界许多学者的共识。重新审视中华科学传统 ,大力进行中西科学传统的比较研究 ,这是中国学术界的一项重要任务 ,借此可以推动新世纪世界科学和中国科学的突破与发展