月桂酸胶束电动毛细管色谱快速测定氨基甲酸脂类农药的研究

以月桂酸表面活性剂和氨水组成缓冲溶液,建立了毛细管胶束电动色谱快速测定七种氨基甲酸脂类农药的方法。对电泳介质的种类及浓度、pH值、操作电压和进样时间等影响因素进行了优化,以45 mmol/L月桂酸(乙醇溶)和120 mmol/L氨水(用0.1 mol/L NaOH调至pH=9.5)为电泳介质,在4.5 min内实现对速灭威、残杀威、克百威、抗蚜威、异丙威、硫双威、双氧威的分离检测。结合固相萃取(SPE)对农田水样进行测定,各农药检出限为2.0～15μg/L,回收率为85%～107%,相对标准偏差为4.3%～8.3%。     

HPLC-MS-MS法测定水体中残留的氨基甲酸酯类农药

应用高效液相色谱-串联质谱(HPLC-MS-MS)联用技术,建立了检测水体中氨基甲酸酯类农药残留的方法。水样经氨基柱固相萃取,二氯甲烷洗脱,梯度流动相洗脱,电喷雾正离子(ESI+)模式采集、选择反应性监测模式(SRM)对定性、定量离子进行MS/MS测定。5种氨基甲酸酯类农药在5～200ng/L范围内线性关系良好,回收率为80%～92%,相对标准偏差均小于10%,方法检出限分别为:异丙威和仲丁威为1.4ng/L,克百威和甲萘威为1.5ng/L,恶虫威为1.6ng/L。该方法适用于水体中氨基甲酸酯类农药残留的检测。     

UPLC-MS/MS同时测定蔬菜中阿维菌素等5种常用农药残留量

建立了同时测定蔬菜样品中阿维菌素、甲氨基阿维菌素苯甲酸盐(甲维盐)、吡虫啉、茚虫威及代森锌残留量的超高压液相色谱-串联质谱法(UPLC-MS/MS)。样品经0.1%氢氧化钠溶液(含10 mmol/L L-半胱氨酸和10 mmol/L EDTA-Na2)预处理后,以乙腈作为提取溶剂,经0.2 g C18+0.05 g石墨化碳(GCB)基质分散固相萃取净化。各待测物经Thermo Hypersil BDS C18(100 mm×4.6 mm,2.6μm)色谱柱进行分离,以10 mmol/L氨水-乙腈作流动相梯度洗脱,串联质谱法对5种农药残留量进行测定。结果表明,代森锌在50~2 000μg/L范围内,另4种农药在5~200μg/L范围内线性关系良好,相关系数(r2)为0.995 1~0.999 9。在0.5~500μg/kg加标浓度下,豆角、辣椒、青菜、黄瓜、芦笋、蕃茄中5种农药的加标回收率为70.8%~103.6%,相对标准偏差(RSD)为4.5%~13.9%;代森锌的检出限为8.2~30μg/kg,定量下限为27~100μg/kg,其余4种农药的检出限为0.02~0.7μg/kg,定量下限为0.07~2.3μg/kg。方法快速准确、经济实用,可满足日常检测的需要。     

固相萃取-高效液相色谱法测定茶叶中有机氮农药残留量

提出了茶叶中5种有机氮农药(速灭威、残杀威、呋喃丹、甲萘威、抗蚜威)残留的高效液相色谱法.样品用丙酮-正己烷(1 2)混合溶剂提取,经石墨碳固相小柱净化,以VP-ODS C18柱分析,乙腈-60 mmol·L-1磷酸(40 60)溶液为流动相,流速为1.0 mL·min-1,检测波长210 nm,外标法定量.在0.10～2.0 mg·kg-1之间的添加水平,5种有机氮农药的平均回收率在80.1%～94.8%之间,相对标准偏差在2.21%～7.13%之问,检出限在0.0125～0.05 mg·kg-1之间.     

QuEChERS-液相色谱-串联质谱法测定植物性食品中30种氨基甲酸酯类农药残留

基于欧洲标准化委员会标准方法(EN 15662)对食品基质的分类,选择6种代表性植物性食品作为基质,系统优化了QuEChERS样品前处理方法;在此基础上,建立了30种氨基甲酸酯类农药的液相色谱-串联质谱分析方法。实验结果表明,除涕灭威砜的线性范围为2~100 μg/kg,其他29种氨基甲酸酯类农药的线性范围均为1~100 μg/kg;6种样品基质在3个添加水平(5、20、100 μg/kg)下的回收率为56.13%~127.6%,相对标准偏差为0.47%~16%;以信噪比(S/N)≥10计,30种农药的定量限(LOQ)为0.041~1.9 μg/kg。本文方法灵敏、有效,适用于植物性食品基质中30种氨基甲酸酯类农药残留的测定。     

化学计量学-同步荧光光谱法同时测定速灭威、残杀威和呋喃丹

在pH 4.0的B-R缓冲溶液中,速灭威、残杀威和呋喃丹能够产生内源荧光,但光谱严重重叠。当波长差Δλ=30 nm时,加入一定量的β-环糊精,3种农药的荧光强度均有不同程度的加强,且荧光强度与农药的浓度呈良好的线性关系,速灭威、残杀威和呋喃丹单组分的测量线性范围分别为0.2~2.0、0.02~0.38和0.04~0.56μg/mL;检出限分别为0.083、0.015和0.020μg/mL。应用多种化学计量学方法,如经典最小二乘(CLS)、主成分回归(PCR)和偏最小二乘(PLS)对同步荧光光谱严重重叠的3种农药混合体系合成样进行光谱解析并比较其分析能力。结果表明,PLS预报各组分的结果较好,采用该模型分析了一些实际食品样品,获得满意的结果。     

QuEChERS/超高效液相色谱-串联质谱法同时测定土壤中67种农药残留

建立了同时测定土壤中67种农药的QuEChERS/超高效液相色谱-串联质谱法(QuEChERS/UPLCMS/MS)方法。样品经乙腈振荡提取、QuEChERS净化,采用超高效液相色谱-串联质谱测定。质谱分析采用电喷雾电离,正负双离子扫描,多反应监测(MRM)模式。结果表明:67种农药在5~500μg/L范围内均呈良好的线性关系,相关系数为0.990~0.999,检出限为0.001~0.010 mg/L;在10、50、500μg/kg 3个加标水平下的平均回收率为58%~111%,相对标准偏差(n=5)为1.1%~19.3%;定量下限为10μg/kg。该方法简单、快速、重现性好、灵敏度高,可满足土壤中67种农药残留的检测要求。     

卷烟主流烟气总粒相物中氨基甲酸酯类农药的前处理研究

采用Envi-carb/NH2复合柱净化,GC/MS法检测,对提取条件、净化条件和检测条件充分优化后,建立了卷烟主流烟气总粒相物中4种氨基甲酸酯类农药(久效威、甲奈威、克百威和抗蚜威)含量的快速分析方法.该方法的线性范围为0.01～10.0mg/L,相关系数(R)大于0.996 6,日内、日间相对标准偏差(RSD)均小于6.97%,检测限(LOD)均为10μg/L,样品的加标回收率均大于90.20%～92.80%.方法用于卷烟主流烟气总粒相物中氨基甲酸酯类农药含量的测定,结果令人满意.     

气相色谱-串联质谱同位素内标法测定中草药中124种农药及其代谢物残留

建立测定中草药中124种农药及其代谢物残留的气相色谱-串联质谱(GC-MS-MS)方法。采用同位素内标法,样品经乙腈提取,采用混合型固相分散萃取剂净化,加入分析保护剂校正基质效应。色谱柱为DB-5MS(30 m×0.25 mm×0.25μm),程序升温,GC-MS-MS测定。124种农药残留在0.005~0.40μg/m L内呈线性关系,在0.06~0.3 mg/kg内的平均回收率为84.8%~108.7%,RSD为2.1%~12%,方法检出限(LOD)为0.005~0.013 mg/kg。该方法适合于中草药中农药多残留的同时检测。     

固相萃取–气相色谱法测定甘草中的六六六、滴滴涕含量

建立了甘草中六六六、滴滴涕农药残留量的固相萃取–气相色谱–ECD测定方法。甘草样品用水浸泡后加入乙腈,以超声辅助振荡提取,采用Florisil固相萃取柱净化,经DB–1毛细管柱(30 m×0.25 mm,0.25μm)分析,进样口温度为220℃,电子捕获检测器温度为320℃。六六六、滴滴涕农药的质量浓度在0.005~0.5μg/m L范围内线性良好,相关系数为0.990 0~0.999 5。在0.05,0.1,0.5 mg/kg 3个添加水平下,2种农药共8个异构体加标回收率为60.1%~122.2%,相对标准偏差为2.3%~15.1%(n=5),检出限为0.25~1.4μg/kg,定量下限为0.56~3.06μg/kg。该方法具有样品前处理操作简单、灵敏度高、试剂用量少、选择性高、重现性好等优点,适用于甘草中六六六、滴滴涕农药残留量的快速测定。     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.