微波消解-电感耦合等离子体质谱法测定鲤鱼、河蚌样品中的铜、镉、铅、铬

建立微波消解–电感耦合等离子体质谱法同时测定鲤鱼、河蚌样品中铜、镉、铅、铬4种重金属元素的含量。以20.0μg/L的Rh作为内标,采用硝酸–过氧化氢消解液,用微波消解仪消解鲤鱼、河蚌等生物样品,在选定的仪器工作条件下测定。铜、镉、铅、铬4种重金属元素的质量浓度在1～100μg/L范围内与其质谱强度呈良好的线性关系,相关系数均为0.999 9,方法检出限为0.01～0.09μg/L。测定结果的相对标准偏差为1.30%～9.95%(n=6),样品加标回收率为91.0%～111%。用所建方法对黄鱼国家标准物质(GBW 08573)进行测定,测定值与标准值基本一致,相对误差均小于7%。该方法简单、快速,灵敏度高,重现性好,适用于大批量生物样品中多种重金属元素的同时测定。     

电感耦合等离子体质谱法测定包装材料中10种有毒元素

建立电感耦合等离子体质谱法测定包装材料中铬,镍,铜,锌、砷、硒、钼、镉、汞、铅10种有毒元素的方法。以硝酸和过氧化氢为消解试剂,采用微波消解法消解样品,在选定的仪器工作条件下进行测定。汞的质量浓度在1～10μg/L范围内,其它9种元素的质量浓度在1～100μg/L范围内与质谱响应值具有良好的线性关系,相关系数均不小于0.999 7,方法检出限为0.000 3～0.027 6 mg/kg。塑料和纸质包装材料样品中10种元素测定结果的相对标准偏差为1.10%～4.44%(n=7),样品加标回收率为85.17%～106.16%。该方法适用于包装材料中多种元素的同时测定。     

ICP-MS法测定镍基单晶高温合金DD416中的镓、锡、锑、铅、铋

建立电感耦合等离子体质谱法测定镍基单晶高温合金DD416中镓、锡、锑、铅、铋元素的含量。以盐酸–硝酸(体积比3∶1)混合酸为消解剂,利用微波消解仪消解样品,以Rh(10μg/L)为内标元素。镓的线性范围为0～50μg/g,锡、锑、铅的线性范围为0～20μg/g,铋的线性范围为0～2μg/g,线性相关系数均大于0.999,检出限分别为0.01,0.2,0.1,0.07,0.006μg/g。用该方法对标准物质进行测定,测定结果与标准值之间的相对误差在7.7%～22.7%范围内。样品加标回收率为98.2%～108.0%,测定结果的相对标准偏差为0.1%～1.5%(n=5)。该方法可以快速、准确地对镍基单晶高温合金DD416中镓、锡、锑、铅、铋元素进行同时测定。     

微波消解-ICP-MS测定皮革中7种重金属元素

建立了微波消解法消解皮革样品,ICP-MS同时测定皮革中的Co,Ni,Cu,Cd,Sb,Hg,Pb 7种微量元素的方法。通过优化微波消解条件、ICP-M S各项参数以及选用~(45)Sc,~(72)Ge,~(115)In,~(209)Bi元素为内标混合液校正基体效应和信号漂移,测得皮革中的7种微量元素的检出限在0.57~2.43μg/L之间,7种元素在25~125μg/L范围内呈现良好的线性关系,线性相关系数均大于0.9999,样品加标回收率在95.5%~106.3%之间,相对标准偏差(n=10)在0.6%~2.2%之间。     

微波消解-双道原子荧光法同时测定家禽肝脏中硒和碲

建立了微波消解样品,双道原子荧光光谱法同时测定家禽肝脏中的Se和Te。优化了仪器工作参数、反应体系及消解条件,考察了Cr3+,Cu2+,Pb2+,Co2+,Zn2+,Ni2+,As3+,Sb3+等8种共存离子的干扰。在选定的最佳实验条件下,Se和Te的方法检出限分别为0.11μg/L和0.077μg/L,日间、日内RSD均小于5%;样品中Se,Te的加标回收率分别在93.2%~104.7%及90.8%~101.3%之间。方法适合于家禽肝脏中非金属元素含量的测定。     

微波消解-电感耦合等离子体质谱法测定砂仁中的铜、铅、砷、镉

建立了微波消解样品,电感耦合等离子体质谱法(ICP–MS)测定黔西南高砷土壤种植的砂仁中痕量铜、铅、砷、镉的分析方法。对微波消解条件进行了优化。为了避免消解试剂对质谱测定的干扰,选择硝酸–双氧水混合溶液(体积比为3∶1)作为微波消解试剂,采用ICP–MS测定消解液中铜、铅、砷、镉的含量。利用校正方程对砷、镉的质谱干扰进行校正。铜、铅、砷、镉4种元素的线性相关系数均大于0.999 2,检出限分别为0.073,0.048,0.39,0.062μg/L,测定结果的相对标准偏差小于4.5%(n=5)。各元素的加标回收率在96.0%～105.0%之间。该方法样品处理快速、简单,溶解率高,测定结果准确、可靠,适用于成批量砂仁样品中铜、铅、砷、镉微量元素的测定。     

微波消解/ICP-MS同时测定粮食、蔬菜中的11种重金属元素

建立了微波消解/电感耦合等离子体质谱法同时测定粮食和蔬菜中11种重金属元素(Cu、Mn、Cr、Pb、Cd、Ni、Sb、Hg、Co、Ag、As)的方法,优化了微波消解条件和仪器测定条件,采用HNO_3-HF-H_2O_2和HNO_3-H_2O_2两种混酸体系,将样品进行完全消解。结果显示,11种金属元素的线性系数不小于0.999 5,方法的检出限为0.001~10.00μg/L,测定的相对标准偏差(RSD,n=5)不大于5.0%。该方法具有快速、简便、灵敏度高、稳定性好、准确度高等优点。     

微波辅助消解-电感耦合等离子体原子发射光谱测定烟草中的重金属

本文以微波辅助消解为样品前处理方法,建立了电感耦合等离子体原子发射光谱法(ICP-OES)测定烟草中Cu、Zn、Cr、Cd、Pb、Mn、Fe 7种重金属含量的分析方法。结果表明:该方法 Pb的检出限为2.00μg/L,其他元素检出限均小于0.90μg/L,回收率在86.1%~116.4%之间,相对标准偏差(RSD)在1.1%~8.1%范围。方法已成功用于部分国内外烟草中的重金属含量检测。     

超级微波消解-石墨炉原子吸收光谱法测定不同类型土壤中的镉

采用超级微波消解仪对样品进行前处理,对比不同消解体系的消解效果,选择合适的消解体系,采用石墨炉原子吸收光谱法测定镉浓度,同时优化基体改进剂、灰化温度等工作参数,确定最佳的分析条件。探讨并建立超级微波消解-石墨炉原子吸收光谱法测定不同类型土壤镉含量的方法。在最优条件下,标准曲线在0～1.0μg/L浓度范围内线性关系良好,相关系数r=0.999,检出限浓度为0.04μg/L,定量限浓度为0.12μg/L,方法准确度为94.5%～110%,相对标准偏差RSD为0.60%～5.4%,方法应用于不同类型土壤标准物质镉的测定,测得结果均在标准值范围内。方法简便快捷、准确高效、用酸量低、节约环保,便于在基层推广,适用于批量处理不同类型镉污染土壤样品。     

电感耦合等离子体质谱法测定手机壳套中14种可迁移元素

建立电感耦合等离子体质谱法测定手机壳套中14种可迁移元素含量的方法。样品经人工模拟汗液溶液振荡处理,使14种特定元素迁移至模拟溶液中,然后进行微波消解,采用电感耦合等离子体质谱法对消解液进行测定。14种元素在各自的质量浓度范围内具有良好的线性关系,相关系数均大于0.999,方法检出限为0.004~0.400μg/L。样品加标回收率为88.2%~99.5%,测定结果的相对标准偏差为2.5%~9.3%(n=5)。该方法操作简便,灵敏度高,线性范围广,定量准确,适用于手机壳套中14种可迁移元素含量的测定。     

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.     

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.     

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.     

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.