微波等离子体发射光谱法测定乳及乳制品中的11种元素

本文采用微波灰化技术处理乳及乳制品试样,利用微波等离子体发射光谱法(MP-OES)测定乳及乳制品中K、Ca、Na、Mg、Fe、Zn、Mn、Cu、Ba、Cr、P 11种矿物质元素.实验对样品前处理条件和仪器工作参数进行了优化.结果表明,K、Ca、Na、Mg、Fe、Zn元素的线性范围为0.2～3.0μg/mL,Mn、Cu、...     

ICP-AES法测定硼硅酸盐玻璃中的常量及微量元素

应用电感耦合等离子体原子发射光谱(ICP-AES)法,对硼硅酸盐玻璃中的常量元素Si、Ca、Al、B及微量元素Fe、Ti、Mg进行测定。在优化的工作条件下,各元素的检出限:SiO20.026μg/mL,Ca0.0002μg/mL,Al0.028μg/mL,B0.005μg/mL,Mg0.0002μg/mL,Fe0.006μg/mL,Ti0.005μg/mL。样品测定结果的相对标准偏差(n=6)在0.02%~1.47%之间,加入标准溶液的回收率为93.0%~103.2%。采用该方法对硼硅酸盐玻璃标准样品进行测定,测定值与标准值一致。     

ICP–AES法测定黄瓜中的8种元素

利用微波消解法消解样品,建立电感耦合等离子体原子发射光谱(ICP–AES)法,对大黄瓜和荷兰小黄瓜两种黄瓜样品中的K,Ca,Mg,Fe,Mn,Cu,Zn,Se 8种元素进行含量测定。K+线性范围为0~100μg/m L,Ca2+,Mg2+线性范围为0~20μg/m L,其余离子线性范围为0~2.0μg/m L,相关系数在0.999 6~1.000 0之间,样品加标回收测定结果的相对标准偏差均小于5%(n=6),加标回收率为93.4%~103.2%。结果表明人体所必须的常量元素K,Ca,Mg在两种黄瓜样品中均大量存在,荷兰小黄瓜中K,Ca,Cu,Mn的含量高于大黄瓜,而Fe,Mg,Se的含量低于大黄瓜,Zn在两种黄瓜样品中含量相当。该法可用于测定黄瓜样品中的K,Ca,Mg,Fe,Mn,Cu,Zn,Se元素含量。     

微波灰化-电感耦合等离子体原子发射光谱法测定原油中的金属元素

采用微波灰化技术消化原油样品,并使用电感耦合等离子体原子发射光谱法(ICP-AES)测定其中Na、Mg、Ca、Fe、V、Ni和Cu的含量。探讨了原油样品中金属元素测定的称样量和微波灰化程序,并优化了仪器工作参数和实验条件。样品经微波灰化处理后,用盐酸溶解残渣,方法对Na、Mg、Ca、Fe、V、Ni和Cu元素的检出限分别为0.07、0.01、0.01、0.01、0.02、0.04和0.03mg/kg,回收率在84.5%～96.6%之间,相对标准偏差在2.1%～6.9%范围。方法简便、可靠,可用于原油中Na、Mg、Ca、Fe、V、Ni和Cu 7种金属元素的检测。     

火焰原子吸收光谱法对中药拳参中六种无机元素含量的测定

采用浓硝酸微波消解法处理样品,利用火焰原子吸收光谱法对中药拳参中常量元素Ca、Mg及微量元素Fe、Cu、、Mn、Zn的含量进行了测定。结果表明,中药拳参中含有丰富的人体必需常量和微量元素,Ca、Mg、Fe、Cu、Zn、Mn的质量分数分别为10 662.860、1 961.242、144.557、9.778、10.166、2.314μg.g-1,各元素加样回收率在96.0%~102.0%之间。该法操作简单、结果准确,是中药拳参中无机元素检测的理想方法。     

微波消解-HR-CS FAAS法快速顺序测定老抽中金属元素

建立微波消解-高分辨连续光源火焰原子吸收光谱法快速顺序测定老抽中Ca,Fe,Mg,Zn的方法。实验选择微波消解作为样品前处理方式,研究了乙炔流量和燃烧器高度对测定结果的影响,通过实验分别确定了测定Ca,Fe,Mg,Zn的最佳参数。在此条件下,快速顺序测定老抽中Ca,Fe,Mg,Zn的质量浓度分别为8.0,31.4,415.8,4.9 mg/L,加标回收率为96.2%~105.2%,精密度(RSD)为0.7%~2.1%。该方法为食品中多元素快速顺序检测提供了科学依据。     

电感耦合等离子体原子发射光谱法(ICP-AES)测定金鸡胶囊中的7种无机元素

建立了测定金鸡胶囊中Ca、Mg、Mn、Fe、Cu、Zn和Sr 7种无机元素含量的分析方法.采用浓硝酸和高氯酸(8+2)的混合酸溶解样品,利用电感耦合等离子体原子发射光谱法(ICP-AES)对各种元素进行测定.金鸡胶囊含有丰富的对人体有益的无机元素,对待测样品的测定结果表明,Ca、Mg、Fe、Mn、Zn、Sr和Cu的含量...     

高压密封消解FAAS法分析5种冬青科苦丁茶嫩芽中无机元素及其分布

采集5种冬青科苦丁茶嫩芽样品,经高压密封消解,用火焰原子吸收光谱法测定Ca、Mg、Mn、Fe、Zn的含量。结果表明,在优化的测定条件下,Ca、Mg、Mn、Fe、Zn的回收率为90.1%~105.4%,测定结果的相对标准偏差为1.35%~3.78%(n=5)。用该方法对茶叶标准参考物(GBW 10016)进行了测定,测定结果与标准值相符合。5种冬青科苦丁茶嫩芽中所测元素的含量存在差异,但其总体分布具有一定的相似性,其中苦丁茶冬青嫩芽中Ca和Zn较高。     

以DDTP为化学改进剂,低温电热蒸发ICP-OES 测定环境样品中的钴和镍

提出了以二乙基二硫代磷酸（DDTP）为化学改进剂,低温电热蒸发ICP-OES法检测环境样品中的钴和镍,对影响金属螯合物形成及其蒸发条件进行了考察与优化。试验结果表明,在pH〉4．5,DDTP质量浓度为8．0g／L的条件下,试剂DDTP可与钴（Ⅱ）,镍（Ⅱ）形成稳定的螯合物。并以螯合物的气态形式从石墨炉中。定量蒸发和传输至等离子体中,用于ETV-ICP-OES检测。钴（Ⅱ）和镍（Ⅱ）的检出限分别为19．6和17．3μg／L,与常规的ETV-ICP-OES法相比待测元素的蒸发温度降低了1200℃左右。方法已用于土壤和水系沉积物标准样品中钴和镍的检测。     

火焰原子吸收光谱法测定水仙桃中六种元素的含量

为给水仙桃中微量元素的检测提供科学方法,采用浓硝酸微波消解法处理样品,利用火焰原子吸收光谱法对水仙桃中Ca、Mg、Fe、Cu、、Mn、Zn 6种元素的含量进行了测定。结果表明,水仙桃中含有丰富的人体必需常量和微量元素,Ca、Mg、Fe、Cu、Zn、Mn的质量分数分别为2658.685、1823.331、205.051、8.662、11.165、4.205μg.g1。方法的加样回收率为96.0%～102.0%。该法操作简单、结果准确,是水仙桃中微量元素检测的理想方法。     

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%.     

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.     

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.     

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.