高效毛细管电泳电导法快速检测复方维生素B片中的VBl、VBl2、VB6和VC

采用高效毛细管电泳电导法同时分离、测定了复方维生素B片中的主要成分VB1，VB12，VB6和VC的含量。研究了运行缓冲溶液的酸度和浓度、电泳电压、进样时间等因素对电泳的影响。在优化的实验条件下：40mmol/L Tris-4mmol/L H3BO3(pH8．0)的缓冲溶液中加入0．30mmol/L CTAB(溴化十六烷基三甲基铵)，分离电压为15kV，上述4组分在5min内得到良好的分离。维生素B1，B12，B6和VC的线性范围分别为5．5～1．0mg/mL；15～1．5mg／mL;1．0～0．40mg／mL和6．6～0．80mg／mL；检测限分别为0．80μg/mL，4．0μg/mL，0．50μg/mL，2．9μg/mL；5次测定峰高的相对标准偏差分别为2．2％，1．6％，3．9％，2．8％。5次测定的平均回收率分别为99％，94％，l00％，97％。     

利用巯基棉富集分离和鲁米诺-过氧化氢-铬(Ⅲ)化学发光体系测定水样中痕量砷

本文提出了用鲁米诺－过氧化氢－铬（Ⅲ）化学发光体系结合巯基棉时As（Ⅲ）的分离．建立了快速简单的测定水样中痕量砷的新方法。检测范围宽（0．10～1．0×104μg／L）、检测下限为3．4×102μg／L，且选择性好。直接用于环境水样的分析，5次测定的相对标准偏差为4．2％～10．6％；回收率为95％～103％。     

断续流动注射-催化原子荧光光谱法测定碘

基于碘对亚砷酸-硫酸铈的催化反应，断续流动进样，用氢化物发生．原子荧光光谱法直接测定As(Ⅲ）的浓度变化，建立了微量碘间接测定的方法。在实验条件下，碘离子的线性范围为0．80μg/L；相对标准偏差为2．3％；检测限为4μg/L．加标回收率为92．5％-98．2％。测定结果与硫氰酸铁-亚硝酸催化动力学法相比具有很好的一致性。     

在线还原富集火焰原子吸收光谱法测定环境水样中Cr(Ⅲ)和Cr(Ⅵ)的形态

采用单阀双阳离子交换树脂微柱并联，设计了双路采样逆向洗脱在线分离富集系统，该系统与原子吸收测量技术相结合，实现了在线分离富集-火焰原子吸收光谱法同时测定水中Cr(Ⅲ)和Cr(Ⅵ)，富集1min时，分析速度为60样/h，测定Cr(Ⅲ)和Cr(Ⅵ)的特征浓度分别为6．08μg/L和11．58μg/L(相当于1％吸收)，线性范围分别为0～1．0μg/mL和0～2．0μg/mL，对质量浓度为100μg/L的Cr(Ⅲ)和Cr(Ⅵ)测定的相对标准偏差分别为2．9％和3．0％、检出限分别为8．70和10．8μg/L。该法对实际水样加标回收率在94．5％～104．3％之间。     

在线还原富集-导数火焰原子吸收光谱法测定环境水样中铬(Ⅲ)和铬(Ⅵ)的形态

采用单阀双阳离子交换树脂微柱并联，设计了双路采样逆向洗脱在线分离富集系统，该系统与原子吸收导数测量技术相结合，实现了在线分离富集．导数火焰原子吸收光谱法同时测定水中Cr（Ⅲ）和Cr(Ⅵ），导数仪用2mV／min档位，富集lmin时，分析速度为60样/h，测定Cr（Ⅲ）和Cr(Ⅵ）的特征浓度分别为0．448μg/L和0．793μg/L(相当于1％导数吸收度)，线性范围分别为0-90和0-180μg/L；对浓度分别为10、20μg/LCr（Ⅲ）和Cr(Ⅵ）测定的相对标准偏差分别为2．85％和2．85％；检出限分别为0．855和1．7lμg/L．该法对实际水样加标回收率在94．7％．104％之间。     

垃圾渗滤液中 As和 Hg的流动注射蒸气发生非色散原子荧光光谱法测定

建立了垃圾渗滤液中As和Hg的流动注射蒸气发生－非色散原子荧光光谱的测定方法。在低温下采用硝酸－过氧化氢体系消化处理样品;硫脲－抗坏血酸将As(V）还原后测定样品中的总As;Hg的测定用Hg蒸气发生原子荧光光谱法。对测量条件进行了优化,在优化实验条件下测得As和Hg的检出限分别为0．08和0．007μg/L,10次测定的相对标准偏差分别为0．48％和0．85％（对8．0μg/L As和1．0μg/L Hg标准溶液）。共存的NaCI、MgCI2、CaCI2、Na2SO4、NaF以及微量共存金属离子（Cd、Se、Zn、Pb、Cu、Fe、Mn、AI）对As和Hg的测定没有干扰。用标准校正曲线和标准加入法对样品测定结果进行了比较,实验结果表明二者吻合较好。     

氢化物原子荧光光谱法测定虾中砷和汞

建立了氢化物原子荧光法同时测定虾中砷和汞的方法。研究了样品前处理及实验条件对测定砷、汞的原子荧光强度的影响，并探讨了共存离子对测定砷、汞的干扰和消除的方法。本方法具有操作简便、快速、灵敏度高等优点，砷和汞的检出限分别为0．026μg/L和0．020μg／L；相对标准偏差分别为1．7％～9．4％和1．2％～9．4％；回收率为98％～106％。     

微波消解冷原子荧光法测定市售猪肉中的痕量汞

采用微波消解，冷原子荧光法测定了猪肉中的痕量汞。汞的回收率在90．7％～98．8％之间；相对标准偏差（RSD）2．62％；检出限为0．010μg/mL；线性范围0～12μg/mL。     

HPLC-ICP-MS测定中药中砷的形态

报道了高效液相色谱-电感耦合等离子体质谱（HPLC—ICP-MS）联用技术测定中药中砷的形态，采用阴离子交换柱，以0．2mmol／L EDTA和2mmol／L NaH2PO4的溶液为流动相，pH6．0，流速为1．0mL／min，成功分离了亚砷酸（AsⅢ）、砷酸（AsV）、甲基砷（MMA）和二甲基砷（DMA）。检出限分别为0．67μg／L（AsⅢ），0．85μg／L（DMA），0．43μg／L（MMA），0．70μg／L（AsV）。中药样品经过（1＋1）甲醇和水的溶液超声提取，离心、过滤、氮气吹干甲醇，超纯水定容。样品加标平均萃取回收率分别为：92．8％（AsⅢ），108％（DMA），104％（MMA），101％（AsV），相对标准偏差（RsD，n=7）均小于10％。     

HPLC–AFS联用测定海产品中砷的形态

建立了高效液相色谱–原子荧光分光光度法测定海产品中无机砷(As V,AsⅢ)、有机砷(DMA,MMA,AsB)含量的方法。样品经含10%(体积分数)HCl的提取液振荡提取、离心分离、二路形态分析预处理、高效液相色谱分离,用原子荧光光度计检测As(Ⅲ),DMA,MMA,As(V);四路条件(过氧化氢氧化和开启紫外灯)形态分析预处理装置处理,高效液相色谱分离,原子荧光光度计测定AsB。As(Ⅲ)线性范围为0～100.00μg/L,r2=0.999 7;DMA线性范围为0～100.00μg/L,r2=0.999 3;MMA线性范围为0～100.00μg/L,r2=0.999 0;As(V)线性范围为0～100.00μg/L,r2=0.999 1;AsB线性范围为0～200.00μg/L,r2=0.999 4。3个样品加标回收率为As(Ⅲ)86.7%～89.4%,DMA 111.2%～117.0%,MMA 109.7%～111.6%,As(V)83.8%～90.7%,AsB 88.3%～90.4%。用该方法测定虾仁(干)5个价态测定结果的相对标准偏差为3.07%～9.93%(n=6)。5个价态的检出限(S/N=2)为As(Ⅲ)0.29μg/L,DMA 0.36μg/L,MMA 0.27μg/L,As(V)0.56μg/L,AsB 1.46μg/L。该方法适用于海产品中As(Ⅲ),DMA,MMA,As(V),AsB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.     

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.