液液萃取-程序升温大体积进样-气相色谱串联质谱法测定地表水中25种痕量有机氯农药

建立了液液萃取-程序升温大体积进样-气相色谱-串联质谱分析地表水中25种有机氯农药(OCPs)的方法。样品由正己烷溶液萃取氮吹仪浓缩后,经HP-5 ms色谱柱分离,在柱流速1.2 mL/min条件下电子轰击电离源多反应监测(MRM)模式进行检测,内标法定量。结果表明,取样量为250 mL时,25种OCPs方法检出限范围为0.32～1.34 ng/L,校准曲线的相关系数范围在0.9990～0.9999之间,各组份质量浓度在0～50.0μg/L线性范围内线性良好。低中高3组加标实际样品25种OCPs和2种替代物测定结果的相对标准偏差为3.5%～13%,加标回收率为74.0%～103%。方法能够满足地表水中有机氯的检测要求。     

气相色谱法测定虾中有机氯农药和多氯联苯残留量

建立了气相色谱法检测虾中12种有机氯农药(OCPs)和7种多氯联苯(PCBs)残留的方法。捣碎匀浆后的样品采用正己烷/二氯甲烷提取,H2SO4(浓)净化,气相色谱仪电子捕获检测器进行分析测定。有机氯农药和多氯联苯的定量限为0.3~1.5μg/kg;在虾中2,10,20μg/kg添加水平的平均回收率为70.6%~102%,相对标准偏差为2.4%~6.2%。方法适用于虾中有机氯农药和多氯联苯的定性定量分析。     

ASE/GC-MS法同时测定海洋沉积物中65种多氯联苯、多环芳烃与有机氯农药

建立了加速溶剂萃取/气相色谱-质谱法(ASE/GC-MS)同时测定海洋沉积物中28种多氯联苯(PCBs)、16种多环芳烃(PAHs)和21种有机氯农药(OCPs)的分析方法.结果表明,ASE的最佳萃取温度为100 ℃,最佳静态时间为5 min.GC-MS同时分析65种化合物时,PAHs的线性范围为0.05 ～5.00 ...     

气相色谱-电子捕获检测法和气相色谱-质谱法同时测定鱼体内19种有机氯农药

建立了气相色谱-电子捕获检测(GC-ECD)法同时测定,及气相色谱-离子阱-多级质谱(GC-IT-MS/MS)法定量确证鱼体中19种有机氯农药(OCPs)残留的检测方法。目标物采用浸渍-振荡法提取,固相萃取(SPE)(脂肪含量≤1.0%)和凝胶色谱(GPC)净化,浓缩,定容后上机测定。草鱼肌肉空白组织中目标化合物的添加浓度为2.0、5.0μg/kg时,GC-ECD法与GC-IT-MS/MS法的回收率分别为72.8%～96%和78.8%～106%,相对标准偏差分别为2.1%～14.9%和4.8%～11%。定量限(S/N=10)分别为0.07～1.44μg/kg和0.10～4.27μg/kg。本方法已成功应用于长江圆口铜鱼体中多种OCPs残留的同时测定。     

气相色谱-质谱法分析蜂蜜中多种有机氯农药残留

建立了气相色谱-电子轰击离子化-质谱法（GC-EI-MS）同时分析蜂蜜试样中12种有机氯农药残留的分析方法.蜂蜜试样用V（正己烷）：V（乙酸乙酯）=5：1混合提取剂超声提取和Florisil硅藻土层析柱净化后,以PCB 103为内标物,采用GC-EI-MS的选择离子监测方式（SIM）分析,同时探讨了一些有机氯农药EI-MS特征离子的结构与断裂机理.当空白试样的加标浓度为10、50、200μg/kg时,加标回收率为80%～112%,相对标准偏差为0.4%～9.8%,方法检出限为0.2～4.0μg/kg,其中8种农药的MDL＜1.0μg/kg,线性范围为10～500μg/kg,相关系数皆大于0.996,此方法已用于蜂蜜试样中多种痕量有机氯农药残留的分析.     

溶胶-凝胶法制备C18固相微萃取头及其在有机氯农药残留检测中的应用

以十八烷基三乙氧基硅烷(C18-TEOS)、四乙氧基硅烷(TEOS)、乙醇、盐和水酸为原料,采用溶胶-凝胶法制备了十八烷基(C18)固相微萃取头,利用所制备萃取头实现了水样中11种有机氯农药的检测。在优化条件下,使用该萃取头对有机氯农药(OCPs)萃取后用气相色谱/电子捕获检测器(GC/ECD)测定,检出限为0.01～0.24μg/L,相对标准偏差为3.0%～13.3%。该方法用于鱼塘水、湖水及自来水中OCPs的检测,结果满意。所制备的萃取头在不同溶剂中浸泡后,对有机氯农药的萃取性能无明显变化。使用50次后,C18萃取头的萃取性能未变化。结果表明,所制备的C18固相微萃取头涂层均匀,具有多孔结构,稳定性高,有很好的实用价值。     

悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量

建立了悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量的方法。样品经石油醚提取、浓硫酸净化、悬浮固化-分散液液微萃取法浓缩后,用气相色谱-电子捕获检测器(GC-ECD)检测,外标法定量。结果表明,9种农药含量在1~100μg/L范围内线性关系良好,相关系数R2在0.99以上,方法检出限(S/N=3)为0.01~0.07μg/kg。9种有机氯农药在1.75,7.00,28.0μg/kg 3个水平添加下,平均回收率范围为83.3%~116.7%,相对标准偏差(RSD)范围为1.5%~14%,方法已用于野木瓜中9种有机氯农药残留的测定。     

固相萃取/气相色谱-质谱法对土壤中有机氯农药的分析及基质效应研究

建立了一种固相萃取/气相色谱-质谱法同时测定土壤中23种有机氯农药的方法,并研究了不同基质效应补偿方式。土壤样品经正己烷∶丙酮(体积比1∶1)提取,弗罗里土小柱净化,采用气相色谱-质谱仪检测。结果发现7种有机氯存在中/强程度的基质效应;在10 mL二氯甲烷∶正己烷(体积比1∶9)+10 mL丙酮∶正己烷(体积比1∶9)为固相萃取的洗脱剂,且脉冲压力为275.8 kPa条件下,可将23种有机氯的基质效应均控制在20%以内。23种有机氯农药在0.4～10μg·mL~(-1)质量浓度范围内线性良好,相关系数(r~2)均不小于0.999 2,检出限为1.0～8.6μg·kg~(-1),定量下限为4.0～34.4μg·kg~(-1);在20、60、100μg·kg~(-1)3个加标水平下空白土壤中的平均回收率为46.3%～127%,相对标准偏差(n=6)为0.68%～15%。采用该方法在某土壤样品中检出α-六六六、γ-六六六、p,p′-DDE、异狄氏剂醛、p,p′-DDT 5种有机氯农药。     

加速溶剂萃取-硅胶萃取净化-气相色谱/质谱法检测地表水中有机氯农药和多氯联苯

建立了加速溶剂萃取-硅胶固相萃取净化-气相色谱/质谱同时检测地表水中15种有机氯农药(OCPs)和82种多氯联苯(PCBs)的方法.对影响OCPs和PCBs回收率的主要因素进行优化,得出最优的萃取条件:3次静态萃取循环,100℃的萃取温度,丙酮/正己烷(1∶1,V/V)为萃取液,静态萃取10 min.在最优条件下,15种OCPs和82种PCBs在加标水溶液中的回收率分别为70.9％～130％和52.5％～89.1％.日内和日间相对标准偏差分别为1.7％～16.1％和2.4％ ～33.3％.OCPs和PCBs混合标样在10～ 800 μg/L范围内线性相关系数(R2)均大于0.995.OCPs和PCBs方法检测限分别为0.13 ～0.38 ng/L和0.10 ～0.32 ng/L.相比于传统萃取方法,本方法回收率高、萃取时间短、试剂用量少.应用本方法测得北京城区地表水中OCPs和PCBs的含量范围分别为n.d.～ 3.45 ng/L和n.d.～4.88 ng/L.     

气相色谱法测定菊花中25种有机氯农药残留量

建立了菊花中25种有机氯农药多残留量的气相色谱-电子捕获检测器分析方法。样品以石油醚-丙酮(体积比1∶1)为提取剂,冰浴超声提取,提取液用浓硫酸净化,采用HP-5与DB1701毛细管色谱柱双柱定性分离,电子捕获检测器(ECD)测定25种有机氯农药的残留量。结果表明:在20、50、100μg/kg 3个添加水平下的回收率分别在69.9%～113.9%、69.4%～100.3%、70.1%～103.1%,相对标准偏差(RSD)分别为2.3%～11.9%、3.2%～10.3%、2.9%～10.8%。方法检出限为4.0μg/kg,定量限为12.0μg/kg,符合农药多残留检测要求。该方法操作简便快速,适用范围广,净化效果较好,可用于菊花中25种有机氯农药多残留量检测。     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

Hard and soft acids and bases: structure and process

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Syntheses and structures of P-anilino-P-chalcogeno- and P-anilino-P-iminodiazasilaphosphetidines and their group 12 and 13 metal compounds

The P-anilino-P-chalcogeno(imino)diazasilaphosphetidines [Me(2)Si(mu-N(t)Bu)(2)P=E(NHPh)] (E = O (3), S (4), Se (5), N-p-tolyl (6)) were synthesized by oxidizing the P-anilinodiazasilaphosphetidine [Me(2)Si(N(t)Bu)(2)P(NHPh)] (2) with cumene hydroperoxide, sulfur, selenium, and p-tolyl azide, respectively. The lithium salt of 4 reacted with thallium monochloride to produce ([Me(2)Si(mu-N(t)Bu)(2)P=S(NPh)-kappaN-kappaS]Tl)(7), which features a two-coordinate thallium atom. Treatment of 4-6 with AlMe(3) gave the monoligand dimethylaluminum complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE]AlMe(2)) (E = S (8), Se (9), N-p-tolyl (10)), respectively. In these complexes the aluminum atom is tetrahedrally coordinated by one chelating ligand and two methyl groups, as a single-crystal X-ray analysis of 8 showed. A 2 equiv amount of 4-6 reacted with diethylzinc to produce the homoleptic diligand complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE](2)Zn)(E = S (11), Se (12), N-p-tolyl (13)). A crystal-structure analysis of 11 revealed a linear tetraspirocycle with a tetrahedrally coordinated, central zinc atom.