直接稀释/超高效液相色谱-串联质谱法测定河豚鱼与织纹螺中2种河豚毒素

建立了直接稀释/超高效液相色谱-串联质谱测定河豚鱼与织纹螺中2种河豚毒素TTX和4,9-anh TTX的方法。样品经乙酸-甲醇(1∶99)溶液提取,高速离心,上清液用80%(体积分数)甲醇水溶液稀释和过滤后直接进样分析。以0.5 mmol/L甲酸铵的0.1%甲酸水溶液-0.1%甲酸乙腈溶液为流动相,采用梯度洗脱方式在ACQUITY BEH Amide色谱柱(100 mm×2.1 mm,1.7μm)上分离,以电喷雾离子源正离子模式(ESI~+)扫描,多反应监测(MRM)模式采集,外标法定量。TTX和4,9-anhTTX分别在0.5～100μg/L、0.5～50μg/L质量浓度范围内呈良好的线性关系,相关系数(r~2)均大于0.99,检出限(LOD,S/N≥3)为100～150μg/kg,定量下限(LOQ,S/N≥10)为300～450μg/kg。在河豚鱼、织纹螺基质中,3个浓度水平下的加标回收率为75.4%～96.8%,日内相对标准偏差(RSD)为2.3%～9.5%,日间RSD为5.3%～9.2%。该方法简便、高效、节约成本,适用于河豚鱼、织纹螺中2种河豚毒素的快速准确检测。     

高效液相色谱-电喷雾串联质谱法同时测定水产品中硝基咪唑类化合物及其代谢物残留

建立了高效液相色谱-电喷雾串联质谱(HPLC-ESI MS/MS)快速测定水产品中硝基咪唑类兽药甲硝哒唑(MNZ)、洛硝哒唑(RNZ)、迪美硝唑(DMZ)及其代谢物羟基甲硝唑(MNZOH)、羟基二甲硝咪唑(HMMNI)残留量的分析方法。样品在弱碱性条件下(磷酸二氢钠缓冲液,p H 8.0)经甲醇-丙酮(3∶1)混合液提取,乙酸乙酯萃取和乙腈正己烷分配脱脂净化;以0.1%甲酸水溶液和0.1%甲酸乙腈溶液为流动相,梯度洗脱,Agilent ZORBAX SB C18RRHD(100 mm×2.1 mm,1.8μm)色谱柱分离;多反应监测正离子模式扫描,同位素稀释内标法定量。结果表明,5种目标分析物在0.25~50μg/L范围内线性关系良好,相关系数为0.998 6~0.999 7;定量下限(S/N≥10)均可达到0.1μg/kg。各基质在0.1,0.5,10.0μg/kg加标水平的回收率为70.7%~105.1%,相对标准偏差为1.7%~8.1%。该方法操作快速、高效、定量重复性好,适用于水产品中硝基咪唑类药物残留的检测。     

高效液相色谱-四极杆/线性离子阱质谱仪测定盐酸决奈达隆中两种基因毒性杂质的痕量残留

建立了高效液相色谱-四极杆/线性离子阱质谱仪(HPLC-QTRAP-MS/MS)测定盐酸决奈达隆药物中两种基因毒性杂质(杂质C和D)痕量残留的分析方法。盐酸决奈达隆药物以0.1%甲酸水溶液-乙腈(20∶80)溶解后,分别采用Agilent Extend-C18色谱柱(1.8μm,2.1 mm×50 mm)或YMC Pack-CN色谱柱(5μm,4.6 mm×250 mm)进行分离,以0.1%甲酸水和乙腈作为流动相分别进行梯度洗脱,电喷雾正离子(ESI+)扫描方式下选择离子监测(SRM)模式对样品进行检测。结果表明,杂质C和D在1.0~50μg/L范围内线性关系良好,检出限(S/N=3)分别为0.20μg/L和0.30μg/L,定量下限(S/N=10)分别为0.80μg/L和1.0μg/L。该方法操作简单、灵敏度高、重现性好,可用于盐酸决奈达隆药物中两种基因毒性杂质痕量残留的测定。     

同位素稀释-液相色谱/质谱法测定生态纺织品中五氯苯酚残留

建立了生态纺织品中五氯苯酚的同位素稀释-固相萃取-液相色谱/串联质谱的分析方法。样品用5%氨水-乙腈溶液(70/30,V/V)提取,用MAX固相萃取小柱净化。以乙腈-水(内含0.1%甲酸和5 mmol/L NH_4Ac)为流动相,采用梯度洗脱,在Shim-pack XR-ODSⅢ色谱柱(100 mm×2.0 mm i.d.,2.2μm)上进行分离,以多反应监测负离子模式进行检测,内标法定量。该方法在0.5～50.0μg/L范围线性关系良好,样品的回收率为80.0%～110.0%,相对标准偏差(RSD)为1.56%～5.39%,定量限为0.5μg/kg,检出限为0.15μg/kg。方法灵敏度高、重现性好,可用于生态纺织品中五氯苯酚的监测。     

高效液相色谱-四极杆/线性离子阱质谱测定替米沙坦中N-甲基邻苯二胺残留量

建立了高效液相色谱-四极杆/线性离子阱质谱(HPLC-QTRAP-MS/MS)测定替米沙坦中N-甲基邻苯二胺残留量的分析方法。替米沙坦药物以水-乙腈(80∶20,体积比)溶解后,采用Agilent Eclipse XDB-C18色谱柱(3.5μm,2.1 mm×100 mm)进行分离,以0.1%(体积分数)甲酸水和乙腈作为流动相进行梯度洗脱,电喷雾正离子(ESI+)扫描方式下选择离子监测(SRM)模式对样品进行检测。结果表明,N-甲基邻苯二胺在2.0~50μg/L范围内线性关系良好(r0.99),检出限(S/N=3)为0.5μg/L,定量下限(S/N=10)为2.0μg/L。该方法操作简单、灵敏度高、重现性好,可用于替米沙坦中N-甲基邻苯二胺残留量的测定。     

全自动固相萃取-高效液相色谱-串联质谱法测定水中150种农药残留

建立了固相萃取-高效液相色谱-串联质谱(HPLC-MS/MS)分析方法测定水中150种农药残留。采用HLB固相萃取小柱净化和富集，待测物经Kinetex XB-C₁₈柱(100 mm×3.0 mm, 2.6μm)分离，以0.1%甲酸水溶液-乙腈为流动相，梯度洗脱；采用电喷雾正离子源(ESI⁺),多重反应监测(MRM)模式监测。实验结果显示，150种农药在各自线性范围内相关系数均大于0.991;检出限(S/N≥3)为0.1～6 ng/L;定量限(S/N≥10)为0.3～20 ng/L;在20、100、200 ng/L三个浓度添加水平下，回收率在60.7%～116%之间，相对标准偏差(RSD)在4.0%～10.2%之间。该方法操作简单、灵敏、快速，适用于水体中农药残留的日常监测。     

RP-HPLC法测定QOA的含量及有关物质

建立了测定QOA含量及有关物质的RP-HPLC方法。采用Sepax C18(4.6 mm×250 mm,5μm)色谱柱,流动相为乙腈与体积分数0.1%乙酸水溶液(体积比为10:90),流速1.0 m L/min,检测波长241 nm,进样体积为20μL。QOA质量色谱峰与其相邻杂质峰能完全分离,QOA质量浓度在0.5~50μg/m L范围内呈良好的线性关系(A=48387ρ-736.4,γ=0.9999),检出限为10 ng/m L(S/N≥3)。方法 RSD为0.45%,重复性试验RSD为0.37%,稳定性试验RSD为0.21%。     

加速溶剂萃取-QuEChERS/超高效液相色谱-串联质谱法同时测定药食同源性食品中双酚类化合物

建立了加速溶剂萃取(ASE)-QuEChERS/超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定药食同源性食品中11种双酚类化合物残留的分析方法。样品经ASE萃取,萃取溶剂为乙腈-乙酸-水(89∶1∶10,体积比),萃取温度为80℃,静态萃取时间为6 min,循环2次。萃取液经QuEChERS法净化,采用ACQUITY UPLC HSS T3色谱柱(2.1 mm×100 mm,1.8μm)分离,以甲醇(含0.1%甲酸)和5 mmol/L乙酸铵水溶液(含0.1%甲酸)为流动相进行梯度洗脱,电喷雾电离源正、负模式下同时进行多反应监测(MRM)测定,同位素内标法定量。11种双酚类化合物在0.5～50.0μg/L范围内呈良好线性,相关系数(r~2)不小于0.996 0,检出限为0.1～0.5μg/kg,定量下限为0.3～1.5μg/kg;3个加标水平的回收率为72.4%～108%,相对标准偏差(RSD)为1.7%～15%。该方法操作简单、快速、灵敏度高、重现性好,适用于药食同源性食品中双酚类化合物的同时快速测定。     

超高压液相色谱-静电场轨道阱高分辨质谱筛查渔用饲料中175种药物

建立了超高压液相色谱-静电场轨道阱高分辨质谱快速筛查渔用饲料中多种类药物残留的方法。饲料样品经1%甲酸乙腈溶液提取,浓缩复溶后加水稀释,离心除沉淀,以0.1%甲酸水溶液和0.1%甲酸乙腈溶液为流动相,经Accucore RP-MS色谱柱(100 mm×2.1 mm i.d.,2.6μm)梯度洗脱分离,H-ESI(Heated Electrospray Ionization)离子化,采用Full M S/dd-M S2(Top N)模式采集数据,利用自建的数据库进行定性分析。当满足母离子质荷比偏差3×10-6;保留时间偏差15 s;同位素质荷比偏差1×10-5、相对丰度偏差25%、综合比对75%;碎片离子质荷比偏差2×10-5且至少有一个碎片与数据库中匹配时认为确证检出。方法在200μg/kg可同时定性确证175种药物,50μg/kg同时定性确证136种药物,10μg/kg同时定性确证116种药物,RSD30%,母离子相对偏差均小于1.9×10-6。200μg/kg加标时,81%的化合物回收率在30%~110%之间。     

通过式净化-高效液相色谱-串联质谱法测定动物源性食品中42种兽药残留

建立了猪牛肉、虾、鱼等动物源性食品中磺胺类、磺胺增效剂及喹诺酮类共42种兽药残留的通过式净化-高效液相色谱-串联质谱分析方法。样品经0.1%甲酸-乙腈溶液匀浆提取,过PRiME HLB小柱净化,浓缩后流动相溶解。以Waters Atlantis T3色谱柱(150 mm×4.6 mm,3μm)分离,用乙腈和0.1%甲酸为流动相进行梯度洗脱,电喷雾电离正离子源(ESI~+)、多反应监测模式保留时间窗口检测,基质匹配标准工作曲线定量。结果表明,42种兽药在1～100μg/kg范围内呈良好线性关系,相关系数(r)均大于0.998,42种兽药的检出限(S/N3)为1.0μg/kg、定量限为(S/N10)为2.0μg/kg,三个添加水平的回收率在81.1%～115.9%之间,批内、批间的相对标准偏差(RSD)为6.8%～22.1%。本方法具有简便、快捷、灵敏度高、定性准确等特点。     

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.