碰撞反应池-电感耦合等离子体质谱法测定膨化食品中的铝

采用密闭高压消解技术对样品进行前处理,建立了膨化食品中铝的电感耦合等离子体质谱测定方法。完善样品前处理条件,优化仪器工作参数,并以45Sc为内标元素消除非质谱干扰,以氦气为碰撞反应气消除质谱干扰。在优化的实验条件下,方法的检出限为13.61μg/L,标准曲线的回归系数为0.999 9。同时采用国家标准方法——分光光度法和原子吸收光谱法验证了方法的准确度,三种方法的测定结果没有显著性差异。实验结果表明,方法简单、快速、准确,适用于食品中铝含量的测定。     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定纳米银抗菌产品中多种微量元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定4种纳米银抗菌产品中多种微量元素的分析方法。比较了湿法消解和微波消解这两种样品前处理方法对样品测定的影响,探讨了消除汞记忆效应的方法,并研究了待测元素的质谱干扰的消除。实验结果表明,采用Au(100μg/L)+HCl(2%)能较好地消除Hg的记忆效应。与湿法消解相比,微波消解可短时间消解样品并获得好的Hg回收率。在优化ICP-MS条件后,各元素线性相关系数均大于0.999。采用微波消解-ICP-MS法对样品进行加标回收,样品加标回收率在84.0%~109%,相对标准偏差在0.97%~13.2%。方法快速、简便,能够满足纳米银抗菌产品中微量元素的定量测定。     

碰撞反应池-电感耦合等离子体质谱法同时测定甘蔗中的9种重金属元素

采用微波消解技术对样品进行前处理,以74 Ge、115In、209Bi、45Sc为内标元素消除非质谱干扰,以氦气为碰撞反应气消除质谱干扰,建立了电感耦合等离子体质谱法同时测定甘蔗中重金属元素铅、镉、砷、铊、钒、铬、锡、钴和镍的方法。在优化的试验条件下,方法的线性范围为0.04~50μg·L-1,相关系数均大于0.999,铅、镉、砷、铊、钒、铬、锡、钴和镍的检出限(3s)分别为5.7,0.11,0.67,0.067,2.8,1.1,3.1,6.2,4.3ng·L-1。方法用于分析标准物质,测定结果与认定值相符。     

乳化辅助微波消解-ICP-ORS-MS快速测定霜膏类化妆品中17种微量元素

采用乳化剂和硝酸体系微波消解样品,带八极杆碰撞/反应池(ORS)的电感耦合等离子体质谱(ICP-MS)法同时测定了霜膏类化妆品中铍、硼、铝、钛、铬、锌、砷、硒、银、镉、锡、锑、碘、钕、汞、铊和铅等17种微量元素.通过优化样品前处理和ICP-MS操作条件,降低了质谱干扰,各元素的检出限(3σ)在0.003 ～0.058 ...     

微波消解-电感耦合等离子体质谱(ICP-MS)法同时测定畜禽粪便中7种重金属元素

粪便样品干燥、研磨后,称取0.25 g样品,加入8 mL硝酸,采用微波消解方法进行前处理.采用KED模式消除质谱干扰,采用内标校正消除非质谱干扰(Ge作为Cu、Zn、Cr的内标,Bi作为Hg和Pb的内标,Rh作为As和Cd的内标),建立了可同时测定畜禽粪便中Cu、Zn、Cr、As、Cd、Pb、Hg 7种重金属元素的微波...     

电感耦合等离子体质谱(ICP-MS)法测定锰矿冶炼烟尘中多种重金属元素

为了准确测定锰矿冶炼烟尘中重金属元素的含量,为锰矿冶炼过程中监测和评价环境影响提供有力的数据支撑,采用HCl+HNO₃+HClO₄+HF消解体系对试样进行前处理,通过选用合适的内标溶液消除测定中的非质谱干扰,采用碰撞池模式和编辑校正方程消除质谱干扰,从而建立了电感耦合等离子体质谱法测定锰矿冶炼烟尘中的Cr、Ni、Cd、Tl、Pb等多种重金属元素的方法。实验结果表明,各元素标准曲线的线性相关系数均大于0.999 9,方法检出限为0.007～0.094 mg/kg,样品测定的相对标准偏差(RSD,n=11)在0.43%～4.9%,样品加标回收率为93.8%～107%。方法具有操作简便、线性范围宽、检出限低、精密度高等优点,满足锰矿冶炼烟尘中Cr、Ni、Cd、Tl、Pb等多种重金属元素同时测定的要求。     

一体化碰撞反应(iCRC)-电感耦合等离子体质谱(ICP-MS)法测定地质样品中痕量稀土元素

钡以及轻稀土元素氧化物对中、重稀土元素的干扰一直是质谱测试中存在的问题。建立了石墨粉垫底碳酸钠-硼酸混合熔剂熔融前处理样品,以103 Rh为内标校正,一体化碰撞反应-电感耦合等离子体质谱(ICP-MS)法测定地质样品中稀土元素含量的方法。探讨了碳酸钠-硼酸混合熔剂熔融前处理样品注意事项、碰撞模式下碰撞气流量和离子透镜的参数优化、干扰校正实验等问题,采用国家标准物质GBW07403、GBW07405、GBW07427、GBW07429验证,实验结果表明,各元素线性关系良好,相关系数均大于0.999,方法检出限在0.01～0.03mg/kg,相对误差为0.13%～7.1%,相对标准偏差为0.79%～6.6%,测定结果与标准值相吻合。对实际样品分析,得到平滑的球粒陨石归一化的稀土元素配分曲线,证明测定结果是合理可信的。方法熔剂用量少,过程空白低,对器皿的侵蚀小,直接加热浸取,简化了操作过程,适用于大批量地质样品中稀土元素的测定。     

-电感耦合等离子体质谱法测定硅锰冶炼渣中8种金属元素

实验采用HCl-HNO₃-HF-HClO₄混合酸为消解体系对样品进行前处理,加入1.0 mL盐酸羟胺溶液(100 g/L)溶解残渣,选择合适的同位素,以¹⁰³Rh为内标测定Cr、Co、Ni、Cu、Zn和Cd,以¹⁹³Ir为内标测定Tl和Pb,建立了电感耦合等离子体质谱(ICP-MS)法测定硅锰冶炼渣中8种重金属元素的方法。实验发现,样品前处理选择HCl∶HNO₃∶HF∶HClO₄=5∶5∶5∶1,并在复溶阶段加入1.0 mL盐酸羟胺溶液(100 g/L)可以完全消解样品,实验采用KED模式和干扰系数校正法消除质谱干扰,样品中待测元素的测定结果不受基体成分的干扰。通过绘制校准曲线及测定流程空白,各元素校准曲线的相关系数均大于0.9999,方法检出限为0.006~0.19 mg/kg,方法定量限为0.018~0.57 mg/kg。对硅锰渣实际样品进行测定,各元素的相对标准偏差(RSD,n=11)在0.83%~4.1%,加标回收率为94.7%~106%;经过人员比对实验,相对偏差为-4.54%~4.24%。测定结果稳定可靠,能满足硅锰冶炼渣中8种微量金属元素含量的分析检测要求。     

微波消解-高分辨电感耦合等离子体质谱法(HR-ICP-MS)测定煤炭中35种痕量金属元素

高分辨电感耦合等离子体质谱可以区分干扰元素和目标元素微弱的质量数差别,能解决大多数多原子、氧化物干扰问题,在煤炭痕量元素分析领域受到关注,但煤炭样品中痕量金属元素尤其是稀土元素受到的质谱干扰挑战未被系统地报道。本文采用HNO3-HF混酸微波消解煤炭样品,优化了消解时间、赶酸、复溶等前处理条件,研究了煤炭中钒、铬、锰、钴、镍、铜、镓、锗、砷、铷、锶、钇、铌、钼、镉、锡、锑、铯、钡、镧、铈、镨、钕、钐、铕、镝、钆、铽、钬、铒、镥、铪、铊、铅、钍共35种痕量金属元素在低、中、高分辨率下的质谱干扰,采用高分辨率模式测定Ge、Nd、Eu、Gd、Ho、Er、Lu,采用中分辨率模式测定Ga,采用低分辨率模式测定其余元素,建立了高分辨电感耦合等离子体质谱测定煤炭中35种痕量金属元素的方法。在优化的实验条件下,各元素标准曲线线性相关系数均在0.9999以上,检出限为0.001~0.082 μg/g。选择煤炭标准样品（SARM 20）进行方法验证,测定结果的相对标准偏差为0.27%~6.27%,测定值与标准值基本一致,标准样品中无认证值的元素进行加标回收试验,加标回收率为85.8%~116.55%。选取俄罗斯其它烟煤、澳大利亚其它烟煤、蒙古炼焦煤、印度尼西亚褐煤、俄罗斯无烟煤、印度尼西亚其它烟煤6个代表性样品进行测试,分析了不同产地煤炭的痕量金属元素含量差异。Mn、Ba、Sr以及稀土元素在6种煤炭中存在显著性差异,可为煤炭原产地溯源分析奠定基础。     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定稀释沥青中23种元素

稀释沥青是一种中间产品,主要用于生产沥青。目前稀释沥青中元素含量的测定方法较少,前处理过程繁琐。本文采用微波消解-电感耦合等离子体质谱法同时测定稀释沥青中铝、钒、铬、锰、铁、钴等23种元素,对研究稀释沥青各元素组成,具有重要意义。通过选择合适的前处理方式,最终采用微波消解稀释沥青,优化样品称样量、消解试剂、赶酸温度,通过引入内标元素对非质谱干扰进行校正,通过调谐优化仪器参数、碰撞反应池He模式、干扰方程、选择合适同位素等手段对质谱干扰进行了校正。样品进行测定时采用45Sc、72Ge、115In、209Bi作为内标元素,对方法的检出限、精密度、准确度等进行考察。在优化的试验条件下,23种元素在一定的质量浓度范围内与其信号强度呈线性关系,标准曲线线性良好,相关系数在0. 9990~1.0000之间,方法的检出限在0.0005~1.02mg/kg之间,方法用加标回收测定回收率,回收率范围在80.0~110.5%之间,对稀释沥青样品平行测定7次,测定值的相对标准偏差在0.47~3.09%之间。利用该方法对进口稀释沥青进行23种元素进行测定,满足国家标准对各项技术指标参数的要求,检出限低,选择性好,结果准确可靠,为稀释沥青类样品中多种元素分析测定提供了新的参考方法。     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.