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微波消解-氢化物发生原子荧光法 总被引:4,自引:0,他引:4
采用微波消解样品,氢化物发生原子荧光法,测定了牡蛎壳中微量砷的含量;通过试验,优化了微波消解的条件和仪器的最佳工作参数;结果表明该法具有快速、简便、准确等特点,砷的检出限为0.05μg/L,线性范围0-32μg/L;样品分析结果的相对标准偏差为0.44%(n=6),加标回收率98%。 相似文献
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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 总被引:9,自引:0,他引:9
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。 相似文献
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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 总被引:1,自引:0,他引:1
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%。 相似文献
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为了建立同时测定紫菜、虾片、鱿鱼干、鲜虾皮等常见水产品中碘和溴含量的方法,通过正交试验设计选择最优提取条件,采用电感耦合等离子体质谱法(ICP-MS)测定元素含量。样品粉碎后加入2%四甲基氢氧化铵,于80℃浸提3 h,然后以103Rh为内标,应用ICP-MS测定127I和79Br含量。结果表明:两种元素在1~1 000μg/L范围内线性相关系数均大于0.999,加标回收率在85.7%~112.1%之间,重现性良好,碘和溴的检出限分别为0.0044μg/g和0.029μg/g,定量下限分别为0.015μg/g和0.097μg/g。该方法简单、便捷、准确,可为水产品中碘和溴的同时测定提供参考依据。 相似文献
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建立了离心式固相微萃取与液相色谱-质谱联用(LC-MS)同步测定尿样中4种莨菪烷烃类生物碱(山莨菪碱、氢溴酸樟柳碱、甲溴东莨菪碱和丁溴东莨菪碱)的方法。样品经C18微柱富集、分离解吸后进行LC-MS测定,前处理过程用时5 min。结果表明,山莨菪碱、氢溴酸樟柳碱和丁溴东莨菪碱在0.1~50μg/L浓度范围内线性关系良好,甲溴东莨菪碱线性范围为0.5~50μg/L,相关系数(R2)均大于0.99。4种莨菪烷碱的检出限(LODs)和定量限(LOQs)分别为0.02~0.15和0.08~0.50μg/L。同一柱、不同柱之间萃取10μg/L莨菪烷碱的精密度良好,相对标准偏差(RSDs)均低于10%。在尿样中分别添加4, 20,80μg/L 3个浓度水平的莨菪烷碱,回收率为80.2%~99.6%,无明显基质效应。该方法适用于生物流体中莨菪碱类物质的同步测定。 相似文献
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流动注射在线萃取色谱预浓集火焰原子吸收法测定钯 总被引:6,自引:0,他引:6
以三异辛胺萃淋树脂为微型柱固定相,采用流动注射在线预浓集与火焰原子吸收法联用技术,对微量钯的测定进行了研究。在0.5mol/L的HCl介质中以7.8mL/min的速率采样90s再用0.1mol/L硫脲-0.5mol/L HCl洗脱;在27h^-1的采样频率下,浓集系数为50倍,浓集效率为22.5min,消耗指数0.23mL。线性范围为0-1000μg/L,检出限为0.34μg/L。钯含量水平50μg/L时,连续11次测定的相对标准偏差为2.6%,并对加氢催化剂中的钯进行了加标回收率实验,回收率为99.3%-101.2%。 相似文献
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铌-桑色素荧光探针猝灭法测定核酸 总被引:4,自引:0,他引:4
探讨了应用铌-桑色素(MR)络合物作为荧光探针测定核酸的方法,最大激发峰与发射峰分别位于428nm与497nm;测定的线性范围分别为:HS DNA 10-110μg/L,CT DNA 0-30μg/L,SM DNA 5-60μg/L与Yeast RNA 200-600mg/L;相应的检出限分别为3.8、1.7、0.96与60μg/L,对络合物与DNA的吸收光谱、荧光偏振与热变性行为进行了测量。结果指出:Nb(V)-MR络合物嵌入DNA的双螺旋结构中。 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