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1.
微波消解-冷原子吸收法定量测定人参中汞的研究 总被引:1,自引:1,他引:0
应用微波消解仪和原子吸收光谱仪,采用氢化物-冷原子吸收光谱法对人参中的汞的定量测定方法进行了研究和探讨。对微波消解仪的消解条件、氢化物-冷原子吸收法的测定条件进行了探讨。在本文选择的条件下,回收率为90.98%-108.96%,相对标准偏差为8.04%-15.77%。与国家标准方法的对比实验无显著差异。 相似文献
2.
应用微波消解仪的原子吸收光谱仪,采用氢化物-冷原子吸收光谱法对人参中的汞的定量测定方法进行了研究。对微波消解仪的消解条件、氢化物-冷原子吸收方法的测定条件进行了探讨。在本法选择的条件下,回收率为90.98%-108.96%,相对标准偏差为8.04%-15.77%。与国家标准方法的对比实验证明,两者无显著差异。 相似文献
3.
微波消解-冷原子吸收法定量测定人参中汞的研究 总被引:1,自引:0,他引:1
应用微波消解仪和原子吸收光谱仪 ,采用氢化物 冷原子吸收光谱法对人参中的汞的定量测定方法进行了研究。对微波消解仪的消解条件、氢化物 冷原子吸收方法的测定条件进行了探讨。在本法选择的条件下 ,回收率为 90 98%~ 1 0 8 96 % ,相对标准偏差为 8 0 4 %~ 1 5 77%。与国家标准方法的对比实验证明 ,两者无显著差异。 相似文献
4.
微波消解—原子荧光光谱法定量测定山梨糖醇液中的砷 总被引:6,自引:0,他引:6
应用微波消解技术和原子荧光光谱仪以氢化物发生原子荧光光谱法测定了山梨糖醇液中砷的研究。对微波消解条件以及氢化物发生条件进行了探讨。在选定的最佳条件下方法的检出限为0.22ng/mL,线性范围为0-80ng/mL。10次测定的相对标准偏差为0.49%-2.16%,回收率为94.8%-102.2%。该结果与国际推荐的湿法消解分析结果相对照,无显著性差异。 相似文献
5.
氢化物发生—电感耦合等离子体原子发射光谱法测定环境样品中痕量铅 总被引:4,自引:0,他引:4
提出了以重铬酸钾-铁氰经钾为氧化剂的铅氢化物发生氧化还原体系。采用连续氢化物发生器,对电感耦合等离子体原子发射光谱法,测定痕量铅的条件进行了研究。选定条件下,以02%硫氰酸钾-0.45草酸为干扰抑制剂,测得铅的检出限为0.09μg/L,相对标准偏差为0.49%。对环境标准物质进行分析,结果令人满意。 相似文献
6.
用硝酸和盐酸分解试样,氯化蒸发分离锗,以发生氢化物-原子吸收光谱法测定砷。本文考察了锗的分离效果,共存元素的干扰和发生氢化物的条件。用本方法测定氧化锗中5.8×10 ̄(-5)%的砷,相对标准偏差为4.5%,方法检出限为6.8×10 ̄(-5)% 相似文献
7.
氢化物发生/原子吸收分光光度法测定食盐中铅 总被引:6,自引:0,他引:6
采用氢化物/原子吸收光谱法测定食盐中痕量铅,使用流动注射氢化物发生器,自动吸入试样和NaBH4溶液,空气/乙炔火焰加热石英管原子化器。对测定条件及共存元素的允许量进行了研究,采用K3[Fe(CN)6]作氧化剂。方法的灵敏度是0.28n/mL/1%吸收,检出限为0.10ng/mL,回收率在94%-102%之间,RSD为2.1%-5.3%。 相似文献
8.
顶空氢化物火焰原子吸收法测定铜精矿中锑 总被引:2,自引:0,他引:2
介绍了顶空氢化物火焰原子吸收法测定铜精矿中锑的方法,讨论了锑测定的量佳条件,方法的灵敏为0.02μg,相对标准差(n=8)5.4%,标准加入法的回收率为84.4%-93.5%。 相似文献
9.
化妆品中Hg、As和Pb的微波消解—氢化物发生ICP—AES法测定 总被引:6,自引:0,他引:6
采用微波消解-氢化物发生ICP-AES法测定化妆品中Hg、As和Pb,加入L-半胱氨酸消除了过渡金属离子的干扰,考察了微波消解、氢化物发生的最佳条件。建立的方法简便快速,测定Hg、As和Pb的RSD分别为0.59%、1.2%、2.4%(n=10),样品加标回收率分别为98.5%、99.3%和100.1%。该法已应用于化妆品的常规测定,得到满意的结果。 相似文献
10.
氢化物—无色散原子荧光法测定螺旋藻胶囊中的微量硒 总被引:18,自引:2,他引:18
研究了氢化物原子荧光法测定螺旋藻胶囊中的微量硒,系统地考察了消解体系;确定了最佳测定条件,共存元素的影响及干扰的消除,硒的检出限为1.3×10^-3mg/L,线性范围为0-0.25mg/L,回收率在97.5%-102.3%之间,RSD小于5%。 相似文献
11.
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%. 相似文献
12.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
13.
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. 相似文献
14.
Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
15.
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. 相似文献
16.
N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
17.
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. 相似文献
18.
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. 相似文献
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20.
《Tetrahedron》2014,70(21):3377-3384
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. 相似文献