高效液相色谱串联质谱法快速测定烟草中5种甾醇的研究

本研究基于自主设计的集萃取、过滤和转移功能为一体的样品萃取瓶,建立了高效液相色谱串联质谱(LC-MS/MS)快速测定烟草中麦角甾醇、胆甾醇、菜油甾醇、豆甾醇和β-谷甾醇的方法。样品在萃取瓶中经水解、皂化和萃取,经LC-MS/MS进行分析检测。结果表明:自主设计的样品萃取瓶可提高前处理效率,5种甾醇在0.1～150 ng·mL~(-1)内均具有良好的线性关系(线性相关系数0.999);检出限在0.015～0.075ng·mL~(-1);平均回收率在93.4%～103.8%之间,日内精密度和日间精密度均小于3.5%,具有较好的重复性。该方法能够满足烟草中5种甾醇快速、准确测定。     

液相色谱-掺杂辅助大气压光电离质谱测定海洋沉积物中的植物甾醇

海洋沉积物中的植物甾醇生物标志物常被用于指示海洋沉积有机物的来源、反演海洋生态和环境演变过程.本研究采用非水反相液相色谱-大气压光电离质谱联用技术(LC-APPI-MS),建立了一种同步测定海洋沉积物中多种常见植物甾醇类化合物的新方法.首先,阐明了植物甾类化合物的APPI一级质谱分析特征,在正离子模式下,植物甾醇类化合...     

固相萃取-同位素稀释-气相色谱-串联质谱法测定化妆品中的二甲苯麝香

建立了测定化妆品中二甲苯麝香的固相萃取-同位素稀释-气相色谱-串联质谱分析方法.膏霜、水剂、散粉、香波、唇膏等不同类型的化妆品样品加入甲醇经超声提取后,样品提取液高速离心处理,浓缩上清液,以Sep-Pak Silica固相萃取柱净化,收集二氯甲烷洗脱液,DB-5 MS(30 m × 0.25 mm, 0.25 μm)石英毛细管色谱柱分离后经NCI-GC-MS/MS多反应监测技术进行定性及定量分析.二甲苯麝香的方法定量限为5 μg/kg,在5～50 μg/kg范围内的3个添加水平的平均回收率为81.1%～86.9%,日内精密度均小于10%,日间精密度均小于12%.本方法准确、快速、灵敏度高,可用于化妆品的实际检验工作.     

固相萃取-超高效液相色谱-电喷雾串联质谱法检测梨树叶中熊果苷

建立了固相萃取净化、超高效液相色谱-串联质谱检测梨树叶中熊果苷含量的方法.将粉碎的梨树叶样品用甲醇提取,ENVITM-18固相萃取柱净化,超高效液相-电喷雾串联四级杆质谱检测,外标法定量.测定时用 Acquity UPLC HSS T3 色谱柱(50 mm×2.1 mm,1.8μm)分离,甲醇-水(V/V,7+93)洗...     

超声萃取/液相色谱-串联质谱法测定染整助剂中的二硬脂基二甲基氯化铵

建立了超声辅助萃取/液相色谱-串联质谱( LC - MS/MS)测定染整助剂中二硬脂基二甲基氯化铵(DSDMAC)的方法.将样品以甲醇为萃取溶剂进行超声萃取,萃取液经过滤后采用LC-MS/MS测定.采用电喷雾离子源,定性离子对为m/z 550.5/298.3、522.5/298.3、522.5/270.3、494.5/...     

聚酰胺固相萃取-超高效液相色谱-串联质谱法同时检测饲料中的6种全氟化合物

建立了饲料中6种全氟化合物的聚酰胺固相萃取-超高效液相色谱-串联四极杆质谱分析法。样品采用酸化乙腈提取,在酸性条件下用聚酰胺固相萃取小柱富集,甲醇淋洗净化,5%（v/v）氨水/甲醇溶液洗脱后采用超高效液相色谱-串联四极杆质谱（UPLC-MS/MS）检测。分析柱为Acquity BEH C₁₈（100 mm×2.1 mm,1.7 μm）;流动相为5 mmol/L乙酸铵-乙腈梯度洗脱;在最佳实验条件下,采用多反应监测负离子模式测定,同位素内标法定量。该方法对6种全氟化合物的检出限均小于0.1 μg/kg;对6种饲料及原料的加标回收率为94.2%~108.9%,精密度（RSD）为1.8%~8.6%（n=6）;在0.5~25 μg/L范围内均呈良好的线性关系,线性回归系数r>0.995。该方法前处理成本低,效果好,适合复杂基质样品的检测。     

一种测定植物甾醇的高灵敏度衍生化HPLC-MS/MS方法

建立以丹磺酰肼为柱前衍生试剂,采用Agilent Poroshell 120 EC-C18(50 mm×3.0 mm,2.7μm)反相色谱柱,甲醇-水(体积比为99∶1)为流动相,流速为0.3 m L/min,进样量为10μL,电喷雾电离源,选择反应监测(SRM)方式正离子检测,测定豆甾醇、β-谷甾醇、岩藻甾醇、麦角甾醇的柱前衍生化高效液相色谱串联质谱法.同时分析测定羊栖菜、海带、紫菜中的甾醇种类及含量.以胆固醇为内标物,采用内标工作曲线法定量,各甾醇线性范围在0.05~100μg/m L之间,相关系数在0.990 3~0.998 1之间,检出限(LODs)在0.2~20 ng/m L之间,定量限(LOQs)在0.667~66.7 ng/m L之间,甾醇类物质灵敏度比高效液相色谱法提高25~500倍.     

同位素稀释液相色谱-串联质谱法测定化妆品中残留的丙烯酰胺

建立了化妆品中丙烯酰胺残留的同位素稀释液相色谱-串联质谱的分析方法。水溶性化妆品样品以水为提取溶剂进行提取,提取液经高速离心处理后,上清液用Oasis HLB固相萃取柱净化;脂溶性化妆品样品以正己烷和水混合溶剂液-液分配萃取。经Waters Atlantis T3色谱柱(150 mm×2.1 mm,3 μm)分离后在多反应监测模式下进行串联质谱定性及定量分析,以13C3-丙烯酰胺为内标定量。方法的定量限为0.1 mg/kg,在0.1～1.0 mg/kg 3个添加水平范围内的平均回收率为87.7%～95.8%,日内测定精密度均小于10%,日间测定精密度均小于12%。该方法能够满足化妆品中丙烯酰胺残留的检测要求。     

高效液相色谱-质谱联用法检测免疫抑制剂及其合并用药

建立高效液相色谱-质谱联用法同时测定人血浆中免疫抑制剂及合并用药12种药物浓度的方法.选用Kromasil-C18色谱柱(50 mm× 4.6 mm×5 μm),以甲醇-乙腈-1mmol/L乙酸铵溶液为流动相,采用梯度洗脱进行分离,样本用甲醇沉淀蛋白后进样,流速:1.1 mL/min;柱温:35℃;进样量:20μL.选用3200QTrap型液相色谱-串联质谱仪的多反应监测(MRM)扫描方式进行检测.12种药物的线性范围为0.2～1000μg/L;定量下限为0.2 μg/L.准确度与精密度结果显示方法日间、日内RSD均小于15％;相对偏差-13％～9.33％,稳定性较好.本方法快速、灵敏,专属性强、重现性好,可用于人体血浆中免疫抑制剂及其常用合并用药共12种药物浓度的测定.     

超高效液相色谱-串联质谱法测定茶叶和土壤中丁醚脲及其代谢物的残留

建立了超高效液相色谱-串联质谱同时快速测定茶叶和土壤中丁醚脲及其代谢物残留量的方法.样品采用乙腈提取,加入乙酸铵和NaCl进行液液分配,PSA结合GCB进行同相分散萃取除杂质,Waters AcquityUPLC BEH C18柱(100 mm× 2.1 mm×1.7 μm)分离,超高效液相色谱-串联质谱法测定.在2....     

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.