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采用分散液相微萃取-连续光源石墨炉原子吸收光谱法,以吡咯烷基二硫代氨基甲酸铵(APDC)为螯合剂,CCl4为萃取溶剂,乙醇为分散剂测定环境水样中痕量Cr(VI),并考察了pH、萃取时间、温度和盐度等影响因素。结果表明,DLLME萃取5 mL水样的最佳条件为:pH 2.0,温度为35℃,螯合剂0.012 g/L,萃取溶剂30μL,分散剂0.5 mL。在此条件下,水样中铬(VI)的检出限为0.005μg/L,线性范围为0.05~2.00μg/L,对0.20μg/L,1.00μg/L Cr(VI)标准液分别测定10次的相对标准偏差为0.3%和2.4%。 相似文献
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建立了石墨炉原子吸收光谱法测定检测工业废渣中痕量元素砷、铅、铬、钡、银的方法。采用悬浮进样,硝酸-硫酸混合酸溶解样品。10g/L Mg(NO3)2作基体改进剂,提高了砷的灰化温度,加入10g/L CaCO3防止钡在石墨炉中形成不易挥发的碳化钡,增加了钡的灵敏度。回收率为98%~112%,测定结果的相对标准偏差为2.22%~4.46%。As的线性范围2~80μg/L,Pb的线性范围1~60μg/L,Cr的线性范围0.5~20μg/L,Ba的线性范围5~150μg/L,Ag的线性范围1~100μg/L。 相似文献
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基于分散剂乙醇(0.5mL)和萃取剂四氯化碳(30μL)的协同作用,可使水样(5.0mL)中痕量铅(Ⅱ)与吡咯烷基二硫代氨基甲酸铵(APDC,0.012g·L-1)所形成的螯合物,在pH 7.0及55℃的条件下迅速借分散液相微萃取(DLLME)进入四氯化碳的液滴中,从而达到样品中痕量铅的分离与富集。其含量用连续光源石墨炉原子吸收光谱法予以测定。铅的线性范围在1.00~40.00μg·L-1之间,其检出限(3s/k)为0.15μg·L-1。应用本法测定了自来水和河水中痕量铅,加标回收率在96.8%~105%之间,测定值的相对标准偏差(n=10)均小于5%。 相似文献
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《理化检验(化学分册)》2015,(10)
基于分散剂乙醇(0.5mL)和萃取剂四氯化碳(30μL)的协同作用,可使水样(5.0mL)中痕量铅(Ⅱ)与吡咯烷基二硫代氨基甲酸铵(APDC,0.012g·L-1)所形成的螯合物,在pH 7.0及55℃的条件下迅速借分散液相微萃取(DLLME)进入四氯化碳的液滴中,从而达到样品中痕量铅的分离与富集。其含量用连续光源石墨炉原子吸收光谱法予以测定。铅的线性范围在1.00~40.00μg·L-1之间,其检出限(3s/k)为0.15μg·L-1。应用本法测定了自来水和河水中痕量铅,加标回收率在96.8%~105%之间,测定值的相对标准偏差(n=10)均小于5%。 相似文献
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《分析试验室》2010,(Z1)
建立了分散液液微萃取-高效液相色谱法测定水样中2-萘酚的分析方法。对萃取剂、分散剂的种类和体积、萃取时间、离心时间、盐浓度等影响萃取效率的因素进行了优化。在优化后的萃取条件下(30μL氯苯作为萃取剂、0.8 mL乙腈作为分散剂、萃取时间为2 min、3000 rpm离心时间为5 min、不加盐)方法的线性范围为0.2~1000μg/L(r=0.9998),检出限为0.05μg/L(S/N=3)。2-萘酚质量浓度为100μg/L时,方法的萃取率为91.4%~105.4%,相对标准偏差为4.7%(n=11)。采用该方法对4种实际水样中的2-萘酚进行了测定,加标回收率在85.5%~104.4%之间,相对标准偏差在2.3%~12%之间(n=3)。本方法可用于环境水样中的痕量2-萘酚的检测。 相似文献
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米面中痕量铍的微波消解-固相萃取/石墨炉原子吸收光谱法分析 总被引:3,自引:0,他引:3
建立了微波消解-固相萃取/石墨炉原子吸收法富集并测定米面中痕量铍的方法.采用微波消解制样,7-(2'-胂酸基-5'-羧酸)苯偶氮-8-羟基喹啉-5-磺酸(H2L)与Be2+螯合形成BeL络合物,C18固相萃取柱(C18-SPE)富集BeL,石墨炉原子吸收法测定C18柱洗脱液中的BeL.最佳实验条件为:采用50 μL pH 3.0的50 g/L H2L水溶液与样品中的铍螯合15 min,水相上柱,用2 mL 50%(体积分数)甲醇溶液洗脱.结果表明,方法的线性范围为0.05 ~14 μg/L,检出限为0.02 μg/L,对实际米面样品测定的加标回收率为90% ~110%,可用于食品等复杂基质中痕量铍的测定. 相似文献
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建立了浊点萃取-石墨炉原子吸收光谱法(GFAAS)测定痕量金属钯的新方法,利用表面活性剂Triton X-114和络合剂2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADMA)对钯进行浊点萃取。研究了溶液pH、试剂浓度、平衡温度和加热时间等因素对浊点萃取及测定灵敏度的影响。优化条件为:pH 5.50 HAc-NaAc缓冲,0.08 mL 5×10-4 mol/L 5-Br-PADMA,0.70 mL10g/L Triton X-114。在最佳条件下,方法的线性范围为0.1~10 ng/mL,钯的检出限为0.068 ng/mL,富集倍率为45倍。该方法可用于环境样品中痕量钯的富集和测定,结果令人满意。 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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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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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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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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《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
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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