气相色谱-质谱法测定肝脏组织中盐酸克伦特罗和盐酸莱克多巴胺

建立了同时测定动物肝组织中盐酸克伦特罗和盐酸莱克多巴胺残留量的固相萃取-气相色谱-质谱分析方法。动物肝组织样品在碱化的条件下用乙酸乙酯和异丙醇混合溶剂提取,提取液浓缩后用乙酸乙酯溶解,然后再用稀盐酸反萃取去除脂肪,调pH值后经SCX固相萃取(SPE)柱净化,洗脱液经氮气吹干后经双三甲基硅基三氟乙酰氨(BSTFA)衍生,采用选择离子模式(盐酸克伦特罗:86、212、262、277,盐酸莱克多巴胺:163、192、234、250)进行测定,外标法定量。盐酸克伦特罗和盐酸莱克多巴胺的检出限分别为0.30和1.00μg/kg。盐酸克伦特罗添加浓度在1.0~5.0μg/kg范围内,添加回收率为77.4%~88.3%;相对标准偏差(RSD)为3.1%~5.1%;盐酸莱克多巴胺添加浓度在4.0~20.0μg/kg,添加回收率为69.8%~82.1%;相对标准偏差(RSD)为3.5%~4.9%;衍生物的峰面积与被测物浓度分别在0.003~1.00 mg/L和0.012~4.00 mg/L范围内呈良好的线性关系,线性回归系数均大于0.999。     

氘代同位素内标QuEChERS法测定动物尿液中3种β_2-兴奋剂药物残留量

采用氘代同位素内标Qu ECh ERS法制备分析样品,气相色谱-质谱法检测动物尿液中的盐酸克伦特罗、沙丁胺醇及莱克多巴胺3种β2-兴奋剂残留量。样品经β-葡萄糖醛酸苷酶酶解后,用氨化乙酸乙酯提取,上清液经无水Mg SO4和N-丙基乙二胺(PSA)吸附剂净化后吹干衍生,气相色谱-质谱进行测定。3种β2-兴奋剂的线性良好,相关系数均大于0.998,在3个加标水平下的平均回收率为95.0%~101.0%,相对标准偏差为2.5%~6.2%,检出限(LOD)为0.3~0.6μg/L,定量下限(LOQ)为1.0~2.0μg/L。该方法操作简单、快速、稳定、精密度高,适用于动物尿液中3种β2-兴奋剂残留的快速测定。     

固相萃取-液相色谱荧光测定动物组织中盐酸莱克多巴胺

采用固相萃取(SPE)前处理净化技术,高效液相色谱(HPLC)测定动物组织中盐酸莱克多巴胺残留量,通过对样品中待测组分的提取、净化,建立了反相高效液相色谱(RP-HPLC)测定动物组织中盐酸莱克多巴胺残留量。线性范围为1.0~100μg/L;相关系数大于0.9998;检出限0.3μg/L;3个不同水平标准添加回收率(n=7)为89.3%~100.5%;相对标准偏差(RSD)为3.9%~5.0%。     

酶解及有机溶剂提取对绵羊血浆和尿样中两种β2-受体激动剂含量测定的影响

采用酶解与有机溶剂提取对绵羊血浆和尿液进行前处理,超高效液相色谱-串联质谱(UPLC-MS/MS)测定两种样品中莱克多巴胺和沙丁胺醇含量,考察了酶解、有机溶剂提取对两种β2-受体激动剂含量测定的影响。结果表明,绵羊血浆中莱克多巴胺轭合率大于95%,沙丁胺醇轭合率约为40%,添加β-葡萄糖醛苷酶/芳基硫酸酯酶进行酶解可有效解离血浆中轭合的莱克多巴胺和沙丁胺醇,测得的含量显著提高;不经酶解处理血浆中莱克多巴胺、沙丁胺醇检测结果的相对偏差均大于40%,重复性差;绵羊尿液中莱克多巴胺轭合率约为57%,沙丁胺醇轭合率低于1%,酶解后尿液中莱克多巴胺检测结果显著提高,对于沙丁胺醇含量测定无显著影响;血浆样品基质复杂程度低于尿液样品,血浆样品目标化合物的基质抑制效应小于尿液样品;有机溶剂提取对血浆和尿液中莱克多巴胺和沙丁胺醇含量检测结果影响不显著,提取过程存在目标化合物损失的可能性,通过内标校正,可消除提取损失对检测结果的影响。     

同位素稀释结合固相萃取快速测定动物组织中β2-兴奋剂

本文采用同位素稀释结合固相萃取技术,测定动物组织中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺4种β2-兴奋剂。动物组织加同位素内标D3-沙丁胺醇和D9-克伦特罗,经甲醇提取后,正己烷脱脂,过SLS离子交换固相萃取柱净化,用BSTFA 1%(φ)TMCS衍生,采用GC/MS进行测定,内标法定量。实验表明,动物组织中添加2.0~10.0μg/kg浓度水平的β2-兴奋剂,方法回收率在72.5%~97.9%,相对标准偏差1.0%~11.4%,线性范围为12.5~500μg/L,样品中特布他林、克伦特罗、沙丁胺醇、莱克多巴胺最低检出限分别为0.5μg/kg、1.0μg/kg、0.5μg/kg和1.0μg/kg。     

在线固相萃取-高效液相色谱-质谱法快速测定绵羊尿液中3种轭合态β-受体激动剂

采用双三元高效液相色谱和液相质谱联用(HPLC-MS/MS)建立了测定绵羊原始尿液及酶解后尿液中β-受体激动剂(沙丁胺醇、克伦特罗、莱克多巴胺)在线SPE(Turboflow)检测的方法。分别对Turboflow柱和分析柱条件进行优化,最终确定样品上样速率4 m L/min,进样体积100μL,样品净化时间0.5 min。本方法的回收率在91.3%~112.2%之间,线性范围为0.1~100μg/L,精密度RSD<1%,日间峰面积RSD<12%,说明方法的重现性和稳定性良好。在对酶解后的尿液检测中发现,对于苯酚类β-受体激动剂(沙丁胺醇、莱克多巴胺),酶解后的尿液中检出化合物含量明显高于未酶解样品,对苯胺类β-受体激动剂(克伦特罗)的影响不大。本方法只需对原始尿液或酶解后的尿液进行过膜处理,样品的在线净化、富集、柱平衡和最终分析可在15 min内完成,大大缩短了日常分析所需时间。本方法操作简单,可用于养殖动物β-受体激动剂大规模筛查。     

急性瘦肉精中毒检材的QuEChERS净化-液质联用快速确证方法

目前液相色谱串联质谱法测定动物源性食品中瘦肉精普遍采用酶水解提取、固相萃取净化的方式处理样品,该方法耗时长、分析成本高。 本研究采用酸水解和酶水解两种提取方式结合QuEChERS(Quick,Easy,Cheap,Effective,Rugged,Safe)净化和高效液相色谱串联质谱建立了动物性食品中特布他林、沙丁胺醇、莱克多巴胺和克伦特罗4种β2受体激动剂的快速定性确证和定量检测方法。 采用酶水解提取-QuEChERS净化处理样品,在电喷雾离子源正离子扫描(ESI+)和多反应监测(MRM)模式下,4种瘦肉精在1.0~20.0 μg/L浓度之间呈线性,线性相关系数均大于0.999,检出限和定量限分别为0.1和0.3 μg/kg,猪肉和牛肉样品中4种化合物的回收率为78.5%~112%,相对标准偏差RSD为2.8%~8.9%。 采用酸水解法代替酶水解提取时,尽管对于样品中莱克多巴胺测定结果稍偏低,但样品前处理时间大大缩短。 两种提取方法结合使用对于提高瘦肉精引起的食物中毒应急处置效率具有重要意义。     

改进的高效液相色谱-串联质谱方法同时测定动物性食品中4种β_2-受体激动剂残留

建立了同时测定动物性食品中克伦特罗、沙丁胺醇、莱克多巴胺和特布他林4种β2-受体激动剂残留的高效液相色谱-串联质谱(HPLC-MS/MS)的分析方法。样品采用质量分数为5%的三氯乙酸振荡提取,用HLB与ProElut PXC固相萃取柱串联净化,采用HPLC-MS/MS在多反应监测(MRM)模式下检测,内标法定量。结果表明:克伦特罗、沙丁胺醇、莱克多巴胺和特布他林的检出限(S/N=3)分别为0.05、0.05、0.05和0.2μg/kg,定量限(S/N=10)分别为0.25、0.25、0.1和0.5μg/kg。空白基质加标水平为2.5、5、10μg/kg时,4种β2-受体激动剂的平均回收率为90.3%~120.5%,相对标准偏差为1.60%~9.33%。该方法采用酸解法提取样品,较酶解法耗时短,速度快,灵敏度高,回收率、重现性好,可有效用于动物性食品中4种β2-受体激动剂残留的快速检测。     

限进印迹柱在线净化/液相色谱-串联质谱法检测动物源食品中克伦特罗与莱克多巴胺残留量

利用针对β-受体激动剂的限进型分子印迹整体柱,通过切换阀的组合和在线净化条件的优化,建立了检测动物源食品中克伦特罗和莱克多巴胺残留的在线净化/液相色谱-串联质谱法。样品经酶解和乙酸铵缓冲液提取后,由在线分子印迹柱净化,CAPCELL PAK C18色谱柱(2.1 mm×100 mm,5μm)分离,多反应监测模式测定,内标法定量。克伦特罗和莱克多巴胺的定量下限分别为0.02μg/kg和0.09μg/kg。在猪肉、牛肉、香肠和奶粉中添加0.05~0.20μg/kg克伦特罗和0.5~2.0μg/kg莱克多巴胺,回收率为84.0%~103.8%,相对标准偏差小于12%。     

应用表面增强拉曼光谱技术快速检测尿样中的β-兴奋剂

应用表面增强拉曼光谱技术与化学计量法相结合分析克伦特罗、沙丁胺醇和莱克多巴胺3种β-兴奋剂的标准溶液.在取自10头猪的尿样中,分别添加5个不同浓度的莱克多巴胺(1～20 mg/L),采用快速的液液萃取法对样品进行前处理,再进行表面增强拉曼测试.结果表明,克伦特罗和沙丁胺醇标准溶液的最低检测浓度为2 μg/L,莱克多巴胺标准溶液的最低检测浓度为0.1 mg/L;通过偏最小二乘法建立模型进行定量分析,3种药物的实际值与预测值的相关系数(R2)为0.9134～0.9368;本方法可检测尿样中1 mg/L莱克多巴胺,经外部验证后模型的实际值与预测值的相关系数(R2)为0 881,相对分析误差(RPD)为2.83;分析尿液中的莱克多巴胺含量所需时间小于30 min,为快速检测莱克多巴胺提供新途径.     

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.