盐析辅助均相液液萃取/分散固相萃取-超高效液相色谱串联质谱法测定蜂蜜中新烟碱类农药残留

以盐析辅助均相液液萃取结合分散固相萃取作为前处理方法,建立了超高效液相色谱串联质谱快速检测蜂蜜中吡虫啉、噻虫嗪、噻虫胺、噻虫啉、啶虫脒及氯噻啉6种新烟碱类农药残留的分析方法。样品用乙腈提取,氯化钠盐析分层,提取液经分散固相萃取法净化,采用超高效液相色谱串联质谱检测器进行分析。考察了萃取剂种类、体积及氯化钠质量对萃取效率的影响,评估了在优化实验条件下的基质效应和方法性能。结果表明:除吡虫啉外,其余5种新烟碱类农药的基质效应均大于10%。6种新烟碱类农药在0.2~100μg/L范围内线性关系良好,相关系数(r2)为0.998 1~0.999 7。加标浓度为1.0~50.0μg/kg时,6种新烟碱类农药的加标回收率为77.0%~106%,相对标准偏差为2.4%~19.8%。方法的检出限为0.2~0.4μg/kg,定量下限为1.0μg/kg。该方法前处理简单,分析时间短,准确度和灵敏度高,重现性好,适用于蜂蜜中6种新烟碱类农药微量残留的快速测定。     

分散固相萃取/超高效液相色谱-串联质谱法测定玉米和土壤中噻酮磺隆-异噁唑草酮及其代谢物残留

建立了分散固相萃取结合超高效液相色谱-串联质谱快速检测玉米和土壤中噻酮磺隆、异噁唑草酮及其代谢物RPA203328与RPA202248残留的分析方法。样品经1%甲酸-乙腈溶剂提取,氯化钠盐析后,提取液经分散固相萃取净化,超高效液相色谱-串联质谱仪检测。考察了提取溶剂及吸附剂种类对分析结果的影响,优化了液相色谱-质谱条件,评估了优化实验条件下的方法性能。结果表明:在玉米样品中,4种分析物的基质效应均大于10%;在土壤样品中,除RPA202248基质效应小于10%外,其余3种分析物的基质效应均大于10%。噻酮磺隆、异噁唑草酮及其代谢物在0.001~1.0μg/m L范围内线性关系良好,相关系数为0.994 5~0.999 5。加标浓度在0.005~0.1 mg/kg范围内的回收率为72.9%~116.5%,相对标准偏差(n=5)为0.75%~17.8%,定量下限为0.005~0.01 mg/kg。该方法前处理简单,分析时间短,准确度和灵敏度高,适用于玉米和土壤中噻酮磺隆、异噁唑草酮及其代谢物残留的快速检测。     

液相色谱法检测水果蔬菜中的烟碱类农药残留

建立了果蔬样品中5种烟碱类农药(噻虫嗪、吡虫啉、啶虫脒、噻虫啉、噻虫胺)残留的液相色谱快速检测方法。样品采用乙腈提取,浓缩,水转溶后经ENVI-18固相萃取柱净化,0.02 mol/L NaOH预淋洗除去柱上中等极性干扰物,100%乙腈1 mL洗脱5种烟碱类残留,反相高效液相色谱-二极管阵列检测器检测。在黄瓜空白基质中0.1~1.0 mg/kg的加标浓度范围内,5种农药的回收率为50.8%~108.9%,相对标准偏差(RSD)小于15%;而苹果、梨、香蕉、西红柿和韭菜空白基质在0.1~1.0 mg/kg添加水平下,5种农药的回收率均大于80%,RSD小于11%。所测试的6种果蔬样品中噻虫嗪、噻虫胺、吡虫啉的检出限(LOD)为0.01~0.02 mg/kg,啶虫咪和噻虫啉的LOD为0.03~0.05 mg/kg,方法可满足水果蔬菜中烟碱类农药多残留分析的要求。     

分散固相萃取/超高效液相色谱-串联质谱法测定玉米和土壤中噻酮磺隆-异唑草酮及其代谢物残留

建立了分散固相萃取结合超高效液相色谱-串联质谱快速检测玉米和土壤中噻酮磺隆、异嚼唑草酮及其代谢物RPA203328与RPA202248残留的分析方法.样品经1％甲酸-乙腈溶剂提取,氯化钠盐析后,提取液经分散固相萃取净化,超高效液相色谱-串联质谱仪检测.考察了提取溶剂及吸附剂种类对分析结果的影响,优化了液相色谱-质谱条件,评估了优化实验条件下的方法性能.结果表明:在玉米样品中,4种分析物的基质效应均大于10％;在土壤样品中,除RPA202248基质效应小于10％外,其余3种分析物的基质效应均大于10％.噻酮磺隆、异唑草酮及其代谢物在0.001 ～ 1.0 μg/mL范围内线性关系良好,相关系数为0.994 5 ～0.999 5.加标浓度在0.005 ～0.1 mg/kg范围内的回收率为72.9％～ 116.5％,相对标准偏差(n=5)为0.75％ ～ 17.8％,定量下限为0.005 ～0.01 mg/kg.该方法前处理简单,分析时间短,准确度和灵敏度高,适用于玉米和土壤中噻酮磺隆、异唑草酮及其代谢物残留的快速检测.     

分散固相萃取-超高效液相色谱-质谱/质谱法测定干果果肉中56种农药残留

针对干果果肉基质含水量低、含糖量较高等特点,建立了改进的分散固相萃取结合超高效液相色谱-质谱/质谱法(UPLC-MS/MS)测定干果果肉培育过程中可能使用的56种农药残留量。样品经水浸润,以0.1%甲酸-乙腈提取,改进的分散固相萃取法(PSA)净化,液相色谱-质谱/质谱法检测,基质匹配标准曲线外标法定量。56种农药在10~500μg/L范围内线性关系良好,相关系数均大于0.990,在5,10和50μg/kg添加水平下56种农药回收率范围为60.4%~127.9%;相对标准偏差在1.1%~20%(n=6)之间;检出限和定量限分别为0.1~1.0μg/kg和0.3~3.1μg/kg。方法适合于干果果肉中56种农残检测。     

分子印迹固相萃取-液相色谱联用法测定3种新烟碱类农药的残留

以噻虫啉为模板分子制备了对吡虫啉、氯噻啉、噻虫啉具有特异性识别的分子印迹聚合物。功能单体与模板分子最佳摩尔比为:n(噻虫啉)∶n(甲基丙烯酸)∶n(苯乙烯)=1∶4∶4。动态吸附和选择性吸附表明,此印迹聚合物能够对目标物快速吸附,且有很好的选择性。Scatchard分析表明,此印迹聚合物对吡虫啉、氯噻啉、噻虫啉最大吸附量分别为31.7,36.7和45.3 mg/g。用此印迹聚合物作为固相萃取吸附剂处理加标样品,目标物的回收率为80.2%~98.8%,RSD为1.2%~4.5%(n=3)。本方法用于实际样品检测,获得了满意的结果。     

分散固相萃取-分散液液微萃取-气相色谱质谱法测定玉米和大米中氟虫腈及其代谢物的残留

建立了分散固相萃取-分散液液微萃取与气相色谱/质谱联用测定玉米和大米中痕量氟虫腈及其代谢物残留的分析方法。使用乙腈和水混合溶液作为萃取溶剂,盐析后,提取液经N-丙基-乙二胺硅烷固相萃取材料(PSA)作为吸附剂后,采用分散液液微萃取步骤将目标物从到微量四氯乙烯中。对影响分散液液微萃取效率的因素,包括萃取溶剂种类及体积、盐等条件进行了优化。在0.02~1μg/m L浓度范围内,线性关系良好(r≥0.9987)。在玉米和大米样品中氟虫腈添加浓度为1.0~25.0μg/g时,平均回收率在70.4%~95.1%之间,相对标准偏差(n=5)在2.6%~12%之间,以最低添加浓度1μg/kg作为定量限。     

分散固相萃取-液相色谱-串联质谱法测定水果中19种酸性农药

建立了同时检测葡萄、苹果和桔子等水果中2,4-滴等19种酸性农药的分散固相萃取-液相色谱-串联质谱(HPLC-MS/MS)方法。葡萄、苹果和桔子样品经乙酸-乙腈(1∶99,V/V)提取后,C18分散固相萃取净化,采用反相C18色谱柱分离。以0.1%甲酸和0.1%甲酸-乙腈溶液作为流动相进行梯度洗脱,采用多反应监测离子模式进行定性分析,基质标准曲线外标法进行定量分析,线性范围在0.01~0.2 mg/kg之间。在0.02,0.05和0.1 mg/kg添加水平下,19种酸性农药的回收率为70.3%～105.3%;相对标准偏差为0.37%～10.9%。本方法的定量限为0.005～0.02 mg/kg。     

基质固相分散-气质联用测定3种基质中28种拟除虫菊酯类农药残留

采用基质固相分散法从3种基质(白菜、梨、鸡肉)中提取、净化28种拟除虫菊酯类农药,用气相色谱-质谱(GC-MS)法进行检测.通过对基质固相分散的条件,如吸附剂、洗脱剂、洗脱体积等参数进行优化,建立了3种基质中28种拟除虫菊酯类农药残留分析的前处理方法.利用所建立的方法进行0.01 mg/kg、0.02 mg/kg和0....     

超高效液相色谱-串联质谱法测定水稻田中甲氨基阿维菌素苯甲酸盐的残留量

建立了水稻植株、土壤、稻田水和稻米中甲氨基阿维菌素苯甲酸盐的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用乙酸乙酯提取,经PCX固相萃取柱净化浓缩,收集的洗脱液再经乙酸乙酯萃取,上层萃取液由氮气吹至近干后,用甲醇定容。试样采用ACQUITY UPLC BEH C18色谱柱进行分离,以乙腈-醋酸铵为流动相,采用电喷雾正离子(ESI+)模式测定。甲氨基阿维菌素苯甲酸盐在1~200μg/L质量浓度范围内呈良好线性,相关系数不低于0.999。在0.1~50.0μg/kg加标水平下,水稻植株、土壤、稻田水和稻米的回收率为70%~110%,相对标准偏差(RSD)为0.3%~15.9%,定量下限(LOQ)为0.1μg/kg。该研究同时发现土壤和水稻植株样品对甲氨基阿维菌素苯甲酸盐表现出明显的基质抑制效应,稻田水样品则表现为基质增强效应。     

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.     

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.     

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.     

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).