流动注射氢化物发生-电加热石英管-原子吸收法测定血清铅

１引言 铅对人体的健康,疾病和生长发育的影响已受到人们越来越多的关注。目前常见的测定血铅的方法有原子吸收光谱法,阳极溶出伏安法等。而用氢化物发生原子吸收法测定食品及环境样品中的铅已有报道,但尚未见用于测定血清铅的报道。本文采用流动注射氢化物发生一电加热石英管．原子吸收法测定血清铅,以Ｋ３Ｆｅ（ＣＮ）６为氧化剂,ＨＣｌ－ＫＣｌ为缓冲剂,该方法具有灵敏度高,准确度及重现性好,操作简便等优点,可用于临床血清样品的测定。２实验部分２．１仪器与试剂ＷＹＸ－９００３型原子吸收分光光度计（沈阳分析仪器厂）,Ｗ…     

氢化物发生辅助雾化火焰原子吸收法测定水中铅

研究了一种提高火焰原子吸收测定铅灵敏度的新方法——氢化物发生辅助雾化的火焰原子吸收法；方法采用硼氢化钠与铅(Ⅳ)在原火焰原子吸收雾化器喷口处反应生成氢化物，以提高火焰原子吸收法的雾化效率；采用重铬酸钾一酒石酸预处理体系，重铬酸钾氧化样品中铅(Ⅱ)为铅(Ⅳ)，酒石酸稳定铅(Ⅳ)的亚稳态化合物；对各种实验参数和干扰情况也进行了研究；方法操作简单、快速，灵敏度比通常的火焰原子吸收法提高了6．8倍；检出限(K=3，n=11)为6．64μg/L，线性范围为0．021～3．2mg／L；测定水样的回收率达94％～99％。     

氢化物发生原子吸收法测定卡托普利

根据卡托普利与醋酸铅反应定量生成沉淀的特点 ,通过用氢化物发生原子吸收法测定沉淀中的铅 ,可间接测定卡托普利的含量。平均回收率 99.8% ,RSD值为 1 .6%     

长缝石英管氢化物-火焰原子吸收光谱法测定化探样品及铅锭中微量锡

长缝石英管氢化物原子吸收法测定锡,具有较低的检出限,是一个方便、快速、灵敏的分析方法,特别适用于地质化探样品及铅锭的测定.通过对锡氢化物发生的酸度等条件进行了研究并提出克服干扰元素的办法.地质样品测定下限为0.5×10~(-6)g,铅锭样品测定下限为0.075×10~(-6)g.完全满足地质化探及铅锭测定的技术要求.     

氢化物原子吸收机理的研究——Ⅱ.石英原子化器表面在原子化过程中的作用

本文研究了氢化物原子吸收中电热石英管原子化器表面在氢化物原子化中的作用,实验证实一些元素氢化物的原子化包含有表面过程,并不是单纯的气相原子化过程。     

氯化物发生原子吸收法测定卡托普利

根据卡托普利与醋酸铅反应定量生成沉淀的特点，通过用氢化物发生原子吸收法测定沉淀中的铅，可间接测定卡托普利的含量。平均回收率99．8％，RSD值为1．6％。     

氢化物原子吸收分光光度法测定食品中砷

食品样中砷的测定一般用银盐法,然而此法灵敏低操作繁琐,本法用氢化物原子吸收分光光度法测定食品中的砷则操作简便、快速、灵敏度高.方法灵敏度为0.8ng·ml~(-1),检出限为0.5ng·ml~(-1).1 试验部分1.1 仪器与试剂WYX-402型原子吸收分光光度计HCF氢化物发生器T型石英管砷标准溶液:100ng·ml~(-1)混合酸:硝酸+高氯酸(4+1)盐酸溶液:0.5mol·L~(-1)硼氢化钾:5g·L~(-1)还原剂:称取碘化钾15g、抗坏血酸10g溶解于离子水,定容至100ml.     

氢化物发生-原子吸收光谱法测定食盐中微量铅

食盐中铅测定采用萃取-原子吸收光谱法，方法使用有机试剂，操作也复杂。采用石墨炉原子吸收光谱法直接测定，氯化钠干扰很大。本文提出氢化物发生-原子吸收光谱法测定食盐中铅。采用WHG-102A2型流动注射氢化物发生器与原子吸收光谱仪配合，载气压力作为自动化能源，流动注射方     

脉冲进样—火焰原子吸收光谱法测定高纯电解铜中微量铁

用脉冲进样－火焰原子吸收法进行高纯电解铜中微量铁的测定，探讨了并优了进样体积，计算时间等试验条件。试样消解后直接测定，避免了常规火焰原子吸收法测试需进行萃取．反萃取分离等繁琐的操作步骤，方法简单，快速、准确，具有较强的实用性。     

氢化物发生石墨炉原子吸收进展

在氢化物发生原子吸收光谱中,石英管是使用较为广泛的原子化器,但由于其气相干扰比较严重,石英管表面性质对分析灵敏度影响较大,因而又发展了石墨炉原子化器。自提出涂钯石墨管原位富集氢化物以后,氢化物发生石墨炉原子吸收受到人们的重视。现将氢化物发生石墨炉原于吸收的主要方法分述如下: 1 石墨炉在线原子化法 所谓石墨炉在线原子化法,是将生成的氢化物直接通入已经达到原子化温度的石墨管里的方法。氢化物可以从石墨炉内气路通入石墨管,也可以从石墨管进样孔进入石墨管。由于石墨炉原子化的温度较高,因而能大大减小可以形成氢化物元素的气相干扰。文献[1]比较了石英管和石墨管两种原子化器的抗干扰能力,其中有关砷和硒的干扰情况见表1。     

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.