GC-MS/SIM法同时测定食品中的苏丹红Ⅰ~Ⅳ

采用气相色谱-质谱(GC-MS)选择离子检测法(SIM),建立了准确可靠、灵敏度高、快速简便的同时测定食品中苏丹红Ⅰ~Ⅳ的新方法。色谱柱为PR-SR石英毛细管柱(20m×0.25mm),进样口温度280℃,柱温200℃,以15℃/min升至280℃;柱前压130kPa,载气He;EI离子源,选择m/z77,105,115,143,176,247,248,261,352,380用于SIM检测,并按不同的采样时间分成4组,每组4个离子,分别对应于每种苏丹红进行定性分析确证;选择苏丹红Ⅰ~Ⅳ各自的分子离子峰m/z248,276,352,380作抽出离子图进行定量分析。苏丹红Ⅰ、Ⅱ的线性范围为0.01~10.0mg/L,苏丹红Ⅲ、Ⅳ的线性范围为0.1~10.0mg/L;检出限苏丹红Ⅰ、Ⅱ为1μg/kg,苏丹红Ⅲ为5μg/kg,苏丹红Ⅳ为10μg/kg;回收率86%~95%。本法与欧洲健康与消费者保护委员会的方法(HPLC法)相比灵敏度高1~2个数量级,分析时间缩短,用色谱保留时间、质谱同时定性,消除了食品中杂质的干扰,结果准确可靠,选择性和重复性好,适用于所有食品成品及原料的检验。     

串级质谱法鉴定食品中苏丹红一号

利用气相色谱串级质谱(GC/MS/MS)法定性定量鉴定食品中染料苏丹红一号,建立了离子阱气相色谱-质谱联用仪分析食品中苏丹红一号染料的方法。结果表明,苏丹红一号在0.045~0.90 mg.L-1浓度范围内呈线性关系,相关系数为0.999 0,检测下限为0.004 5 mg.kg-1,回收率在83.1%~103.2%之间。方法具有样品预处理简单、灵敏度高、检出限低于现行国家标准水平,确证能力强等特点,满足食品中苏丹红一号的定性定量监测。     

气相色谱-质谱法测定奶粉及奶制品中的三聚氰胺

摘采用气相色谱-质谱（GC-MS）分析技术,选择离子检测法（SIM）,开发出一种准确可靠、灵敏度高的测定奶粉及奶制品中三聚氰胺的新方法。色谱柱为DB-1 Ms石英毛细管柱,进样口温度280℃,柱温75℃,保持1min,再以30℃／min升至290℃。载气He,流量1．0mL／min。EI离子源,选择m／z 171、285、327、342用于SIM检测,根据这4个离子的抽出离子色谱图的峰面积比进行目标物确证,以基峰m／z 327做定量分析。三聚氰胺的线性范围为0．01～50mg／L,平均回收率为90％～98％,检出限为1μg／kg,定量下限为5μg/kg。该法与现有方法相比灵敏度提高了2个数量级,用色谱保留时间、质谱同时定性,消除了奶粉及奶制品中杂质的干扰,避免了可能产生的假阳性,结果准确可靠,选择性和重复性好,适用于奶粉及奶制品的检验。     

高效液相色谱-串联质谱法同时检测化妆品中6种禁用着色剂

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时测定膏状和粉状化妆品中苏丹红IV、酸性紫49、苏丹蓝2、溶剂红49、碱性紫1和颜料橙5等6种禁用着色剂的检测方法。样品经乙醇-乙腈(3:2, v/v)超声振荡提取20 min、离心净化及氮吹浓缩后,在Luna C18色谱柱(150 mm×2.1 mm, 5 μm)上进行反相液相色谱分离,以甲醇和10 mmol/L乙酸铵溶液为流动相进行梯度洗脱,采用多反应监测(MRM)模式进行质谱测定。根据保留时间及质谱图上特征离子的相对丰度比进行定性,外标法定量。结果表明: 6种着色剂的定量限(信噪比为10计)为0.1～10 μg/kg,回收率为86.67%～98.22%,相对标准偏差(RSD)为4.01%～7.01%。该方法简便、快速、灵敏度高且重现性好,适合于化妆品中禁用着色剂的定性与定量。     

高分辨热裂解气相色谱/质谱法快速定性检测农产品中的单增李斯特菌

要在高分辨率热裂解气相色谱/质谱(HRPGC/MS)系统中采用选择离子检测法(SIM),建立了准确可靠、灵敏度高、快速简便的检测农产品中单增李斯特菌的方法.裂解条件:起始温度50℃;升温速率20℃/min,裂解室温度230℃;裂解温度650℃;裂解时间为10 s.气相色谱条件:载气为氦气;恒定流速0.9 mL/min;DB-WAXTER毛细管色谱柱;起始温度45℃;保持4min,以6℃/min的速率上升到100℃,然后以10℃/min上升到200℃,接着以12℃/min上升至250℃,并保持25 min.分流比为50∶1.EI离子源.选择色谱保留时间19.056 min,鉴别离子m/z 54,98,用于SIM检测.通过对单增李斯特菌、2种空白农产品和2种不同农产品污染单增李斯特菌的样品检测结果表明,HRPGC/MS方法检测不同黄瓜、牛肉农产品中单增李斯特菌,均能得到很好的反映.本方法分析时间缩短,用保留时间、质谱同时定性,消除了不同种类农产品杂质的干扰,结果准确可靠,选择性和重复性好,适于快速检测农产品中的单增李斯特菌.     

气相色谱-质谱法测定聚醚砜奶瓶中二苯砜的含量及迁移量

采用气相色谱-质谱联用仪(GC-MS)对聚醚砜(PES)奶瓶中的二苯砜进行定性确证和定量分析。样品粉碎并用三氯甲烷超声溶解后,用乙腈沉淀树脂。选用HP-5MS色谱柱并使用选择离子扫描(SIM)模式进行定性和定量分析。定性离子为m/z77、97、125和218,定量离子为m/z125。二苯砜的线性范围为0.1～100mg/L,仪器的定量检出限为0.004mg/L。奶瓶样品中二苯砜的加标回收率为91%～113%,相对标准偏差(RSD)小于7.7%。将奶瓶进行迁移实验后,水、酸性和油性食品模拟物分析的加标回收率分别为88%～102%、96%～111%和89%～110%,RSD分别为5.2%、5.4%和8.7%。     

高效液相色谱-质谱法对饲料及食品添加剂中三聚氰胺的测定

建立了饲料中三聚氰胺的高效液相色谱-质谱测定方法.色谱条件:Kromasil C18柱(4.6 mm×250mm,5 μm),流动相:乙腈-0.1%(体积分数)甲酸(体积比5:95),流速0.4 mL/min.采用正离子模式的电喷雾质谱检测,以一级质谱得到的准分子离子m/z 127作为母离子,进行碰撞诱导解离(CID)二级质谱(MS2)分析,选择母离子和MS2的碎片离子m/z 85、109定性确证,提取m/z 85、109、127三个离子质量色谱峰面积定量.实验优化了质谱条件.线性范围为0.01～0.5 mg/L,检出限0.01 mg/L(S/N=3),回收率为80%～99%.     

超声波提取-气相色谱-质谱联用法测定苏丹红Ⅰ残留量

研究了苏丹红Ⅰ的气-质联用检测方法。样品中的苏丹红Ⅰ用超声波提取,采用选择离子(SIM)方式,据保留时间和特征离子丰度比对其进行确证。此方法可以在13 min之内定性和定量地快速检测苏丹红Ⅰ残留,通过多次试验验证,添加量为0.01~1.00μg,回收率在82%~97%之间,相对标准偏差小于5%,检出限为6.0×10-4μg/g。     

超高效液相色谱-串联质谱快速筛查葡萄酒中的14种禁用食品添加剂

建立了同时测定葡萄酒中14种禁用食品添加剂的超高效液相色谱-电喷雾电离串联质谱(UPLC-ESI-MS/MS)分析方法。采用UPLC BEH C18(100 mm×2.1 mm×1.7 mm)色谱柱,对流动相的组成、缓冲液离子强度及质谱的各种参数进行了优化。结果表明,流动相的离子强度对食品添加剂的质谱检测有重要影响,以含1 mmol/L甲酸铵-甲酸缓冲液(pH 3.9)-乙腈为流动相,梯度洗脱,柱温35℃,可以在6 min内完成14种食品添加剂的分离和检测。在ESI负离子模式下,采用选择离子监测方法进行测定时,除三氯蔗糖、日落黄和酸性红13的检出限分别为10,2和2 mg/L外,其它11种的检出限在0.01~1.0 mg/L之间。回收率为93.8%~106%,相对标准偏差小于3.1%。本方法快速、准确、灵敏度高,可用于葡萄酒及其它复杂基质食品中的低剂量、多种禁用食品添加剂的同时筛查。     

气相色谱–质谱法测定紫外光固化黏合剂中(2,4,6-三甲基苯甲酰基)二苯基氧化膦

建立测定紫外光固化黏合剂中(2,4,6-三甲基苯甲酰基)二苯基氧化膦(TPO)的气相色谱–质谱检测方法.样品在甲苯中超声萃取,采用DB–5HT型分离色谱柱(15 m×0.25 mm,0.1μm),用质谱仪进行检测,以TPO的特征离子碎片和保留时间定性,色谱峰面积定量.结果表明,TPO的质量浓度在1～20 mg/L范围内...     

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.