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采用微波消解样品前处理手段以及双道原子荧光光度计,建立了微波消解一氢化物发生原子荧光光谱法同时测定化肥中砷、汞含量的方法。通过试验确定了样品前处理方法,对负高压、灯电流,载气、屏蔽气、原子化器高度、酸度等测试条件进行了优化。在优化的工作条件下,砷、汞含量分别在0-50ng/mL和0—1.0ng/mL范围内与荧光强度呈良好的线性关系,线性相关系数分别为0.9996,0.9996,检出限分别为0.085,0.008ng/mL,回收率分别为88.8%~107.4%,90.0%~120%,测定结果的相对标准偏差均小于7%(n=6)。 相似文献
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采用盐酸为介质,以顺序注射-氢化物发生原子荧光法测定生产用水中的锑含量.通过正交实验确定了仪器工作参数,研究了介质浓度、KBH4浓度、硫脲一抗坏血酸加入量等因素对测定结果的影响,探讨了共存离子的干扰.在选定的最佳实验条件下,方法的检出限为0.011ng/mL,线性范围0~8ng/mL,相对标准偏差为2.78%~6.20%,加标回收率为91.0%~99.1%.该方法操作简便,灵敏度高,准确度好,与微波消解法相比较,两者无显著性差异. 相似文献
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断续流动-氢化物发生原子荧光法测定浓缩苹果汁中的砷 总被引:5,自引:0,他引:5
用断续流动-氢化物发生原子荧光法测定了浓缩萍果汁中的砷含量。确定了仪器的最佳条件,探讨了酸介质,硫脲-抗坏血酸用量,硼氢化钾加入量对测定As的影响。在选定的操作条件下,砷的检限为0.43ng/mL,相对标准偏差为3.4%-6.3%,加标回收率为94.0%-101.5%本方法简便,快速,灵敏,准确,应用于浓缩苹果汁中As的测定,得到满意的结果。 相似文献
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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
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本文建立微波消解样品,氢化物发生—荧光光谱法测定食品中汞的方法,建立微波消解的最佳分析条件。优化了原子荧光光谱仪的参数设置,以及选择了汞蒸气的最佳条件。该方法检出限为0.004 ng/mL,加标回收率为92.9%~98.7%,相对标准偏差(n=7)为0.81。本方法具有操作简单、快速、干扰小、灵敏度重复性好的优点。 相似文献
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氢化物发生-原子荧光光谱法测定化妆品中铅含量 总被引:3,自引:0,他引:3
建立氢化物发生一原子荧光光谱法测定化妆品中铅含量的方法。通过试验确定了仪器最佳工作参数及最适宜的分析条件。铅标准溶液浓度在0—20ng/mL范围内,标准曲线具有良好的线性,线性回归方程为If=97.4245c+4.8182,相关系数r=0.9998。检出限为0.25ng/mL,回收率为89.0%-105.8%,测定结果的相对标准偏差不大于3.14%(n=11)。 相似文献
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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
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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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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
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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
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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
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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
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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
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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
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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. 相似文献
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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. 相似文献