苯醚甲环唑在香蕉和土壤中的残留分析方法研究

建立了苯醚甲环唑在香蕉和土壤中的残留分析方法。样品经乙腈或丙酮、乙酸乙酯提取,中性氧化铝柱净化,GC-ECD检测。方法在0.004~0.4μg/mL范围内有良好的线性关系,香蕉和土壤中苯醚甲环唑最低检测质量分数为0.004 mg/kg。样本中添加量为0.004~1.0 mg/kg时(n=5),平均回收率为81.4%~106.3%,相对标准偏差为1.5%~11%;方法的准确度和精密度均满足农药残留分析的要求。     

全自动凝胶净化-浓缩-固相萃取/气相色谱-质谱法测定紫皮石斛中有机磷农药残留

建立了以凝胶渗透色谱(GPC)和固相萃取(SPE)净化、气相色谱-质谱(GC-MS)法同时测定紫皮石斛中10种有机磷农药残留的方法。样品用乙腈超声提取,提取液经GPC去除类脂杂质和大分子物质,后经Envi-Carb/NH2固相萃取柱净化,选择离子(SIM)监测模式检测,外标法定量。在26min内10种农药得到很好的分离,农药残留量在0.02~0.5μg/mL,方法的线性良好,相关系数为0.997 3~0.999 9,农药加标浓度为0.05mg/kg和0.2mg/kg时,加标回收率在70.4%~115.8%,相对标准偏差在2.8%~9.6%,满足国家标准要求,检出限为0.005 2~0.011mg/kg。方法简便、快速、灵敏、准确,能够运用于石斛中多组分有机磷农药残留的定性和定量分析。     

中药材农药多残留快速检测方法的研究

研究和建立了中药材中53种农药残留的快速检测方法。中药材样品经过1%醋酸乙腈溶液提取、分散固相萃取法净化,采用气相色谱-质谱(GC/MS)的选择离子监测方式(SIM)进行定性和定量分析。53种残留农药在0.01~31.00mg/L范围内呈现良好的线性关系,定量限在3.3~123.3μg/kg之间,加标回收率在76.2%~109.8%之间,相对标准偏差在1.7%~13%之间。该方法,可快速测定中药材中的农药残留。     

加速溶剂萃取-凝胶色谱净化-气质联用测定土壤中15种有机氯农药残留的方法研究

建立了加速溶剂萃取-凝胶色谱净化-气质联用同时测定土壤中15种有机氯农药的分析方法。优化了凝胶色谱(GPC)净化的条件,比较了凝胶色谱净化及浓硫酸净化法对15种有机氯回收率的影响。结果表明,采用GPC净化能够有效避免浓硫酸净化对氯丹、异狄氏剂、硫丹、甲氧滴滴涕等农药回收率的影响,GPC净化的最佳收集时间为10~15 min,15种有机氯农药的回收率为56%~122%。15种有机氯农药在0.03~6.0 mg/L范围内具有较好的线性,相关系数达0.999以上,方法的检出限为0.1~5.0μg/kg,定量下限为0.4~16.0μg/kg。采用该方法对实际样品进行加标回收率实验,土壤样品的加标回收率为68%~122%,相对标准偏差为1.2%~5.9%。该方法简单、快捷、灵敏度高,已用于实际土壤样品的检测。     

高效液相色谱-串联质谱法测定粮谷中9种氨基甲酸酯类农药残留

本研究采用了高效液相色谱-串联质谱联用(HPLC-MS/MS)技术,建立了高灵敏度的同时检测粮谷中9种氨基甲酸酯类农药残留量的方法。样品经乙腈提取,中性氧化铝填充柱净化,然后采用HPLC-ESI( )-MS/MS测定。对液-质分离条件和样品前处理条件进行了优化。9种氨基甲酸酯类农药在0.1~100μg/L范围内线性良好,相关系数为0.9986~0.9998。在0.001~0.05mg/kg浓度范围内,平均加标回收率在73.40%~102.01%之间;相对标准偏差为1.25%~9.94%。该方法简便、快速、灵敏、净化效果好。可同时满足进、出口粮谷中多种氨基甲酸酯类农药残留量的检验工作需要。     

在线净化-高效液相色谱双检测器法测定土壤中多菌灵、磺胺类、新烟碱类农兽药残留

建立了同时检测对土壤中磺胺脒、磺胺嘧啶、磺胺甲恶唑、烯啶虫胺、吡虫啉、噻虫啉、多菌灵7种农药残留的在线净化-双检测器-高效液相色谱新方法。实验对提取净化和分析条件进行了优化,得出最佳实验条件:土壤样品经提取液(甲醇:乙腈:二氯甲烷=5:4:1,V/V/V)提取,氮吹浓缩后直接进样,经在线固相萃取(SPE)柱在线净化,梯度洗脱经反相C18色谱柱分离,二极管阵列(DAD)检测器串联荧光(FLD)检测器检测,外标法定量,12 min内即可完成7种农兽药的检测。7种农药检出限为1.1~3.0×10~(-3)mg/kg(S/N=3),线性范围内线性相关系数均在0.9999以上。空白土壤样品在0.05,0.10,0.32 mg/kg添加水平的平均加标回收率为71.92%~103.88%,相对标准偏差为0.07%~4.1%。     

QuEChERS-在线凝胶色谱-气相色谱-质谱法测定植物油中34种农药残留

建立了葵花油、大豆油和玉米油中34种中高毒农药的快速筛查方法。样品采用改进的QuEChERS方法进行提取净化,提取液采用在线GPC-GC-MS检测。结果表明,34种农药在0.01~0.2 mg/L范围内具有良好的线性关系,相关系数为0.9913~0.9997。除p,p’-DDE,p,p’-DDD,p,p’-DDT外的31种农药在葵花油、大豆油和玉米油中的检出限分别为0.0692~2.28μg/kg,0.0559~2.01μg/kg,0.0584~2.14μg/kg;在0.05和0.1μg/g添加水平的平均回收率分别为70.3%~115.4%,69.5%~112.6%,70.2%~116.1%;相对标准偏差(RSD,n=6)分别为2.9%~13.3%,3.9%~13.5%,4.2%~12.1%。本方法具有操作便捷、快速等特点,适用于葵花油、大豆油和玉米油中34种农药残留的快速筛查与检测。     

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。     

气相色谱-质谱法同时测定土壤中30种农药残留

采用气相色谱-质谱法同时测定土壤中30种农药残留。样品经过丙酮-正己烷(1+1)混合溶液均质提取,再用正己烷进行萃取,弗罗里硅土柱净化后,采用HP-5MS色谱柱分离,选用电子轰击离子源和选择离子监测模式进行质谱分析,外标法定量。30种农药的线性范围为0.1~1.0mg·L-1,检出限(3S/N)为3.8~9.6μg·kg-1。加标回收率在75.8%~103%之间,测定值的相对标准偏差(n=6)在5.6%~9.7%之间。     

QuEChERS法提取-气相色谱-串联质谱法测定生态纺织品中31种农药残留

采用QuEChERS法提取-气相色谱-串联质谱法同时测定生态纺织品中31种农药残留。样品粉碎后用乙腈萃取,提取液经无水硫酸镁和氯化钠除水后,用乙二胺-N-丙基硅烷和C18吸附剂净化,离心后过膜。待测物在Thermo TR-RESTICIDE石英毛细管色谱柱上分离,采用电子轰击离子源和选择反应监测模式进行质谱测定。31种农药的线性范围均为0.01~1.00mg·L-1,检出限(3S/N)在0.005~0.007mg·kg-1之间。加标回收率在80.3%~99.9%之间,测定值的相对标准偏差(n=6)小于7.0%。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.