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为建立催化动力学荧光法测定痕量甲醛的新方法,基于在酸性介质中,甲醛催化KBrO3氧化藏红T的褪色反应,使其荧光猝灭的原理,将反应体系在沸水浴中加热8 min,流水冷却3min,采用动力学荧光法测定痕量甲醛。结果表明,甲醛在0.02~0.14μg/mL范围内与△F值呈良好的线性关系,线性方程为△F=-1.642 8+274.12C(μg/mL),r=0.996 9,检出限为0.011μg/mL。该法简便,快速,常见共存物质干扰小,可用于水发食品及其它食品中甲醛含量的测定,加标回收率为84.63%~94.93%。 相似文献
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柱前衍生-高效液相色谱法测定蔬菜中甲醛含量 总被引:2,自引:0,他引:2
建立了蔬菜中甲醛含量的高效液相色谱分析方法。样品用水提取、2,4-二硝基苯肼衍生及二氯甲烷萃取、浓缩后,采用Waters Sunfire C18色谱柱(250×4.6 mm,5μm)分离,流动相为乙腈-水(1∶1,V/V),在355nm波长处紫外检测。甲醛在0.1~2.0μg/mL浓度范围内呈线性关系,相关系数0.9989,方法检出限为1.0 mg/kg,在2~10mg/kg添加浓度范围内,甲醛平均回收率为78.1%~114.2%,相对标准偏差在0.8%~9.5%之间。 相似文献
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建立了用甲醛衍生测定农药比久样品中微量的偏二甲肼的方法。采用甲醛与偏二甲肼柱前衍生,在室温、中性溶液中反应10 min,生成确定量的有较强紫外吸收的偏二甲腙,不须富集可直接用HPLC法测定偏二甲肼。研究了甲醛与偏二甲肼的反应条件及产物的光谱特征,测得衍生物的最大吸收波长λmax=237 nm和表观摩尔吸光系数ε=3.6×103(L.mol-1.cm-1),选定ZorbaxODS色谱柱,V(磷酸盐缓冲溶液,pH 7)∶V(甲醇)=94∶6为流动相,检测波长为237 nm。结果表明:在0.56~960μg/mL范围内回归方程为:A=0.4677ρ-0.2790,R2=0.9998,检出限为1.3μg/g,回收率为97.5%~103.4%,相对标准偏差为0.9%~1.8%。 相似文献
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建立了用1,3-环己二酮-甲醛作为荧光衍生试剂测定氨苄西林钠的方法。氨苄西林钠与1,3-环己二酮-甲醛反应生成一种强荧光物质。其最大激发波长是336 nm,最大发射波长是420 nm。氨苄西林钠浓度在0.01~0.6μg/mL范围内与相对荧光强度呈线性关系,线性方程为ρ=0.0007931F-0.06133,线性相关系数为0.9998,相对标准偏差为1.8%,检出限为10 ng/mL,回收率为97.0%~105.9%。考察了pH、温度、放置时间、干扰离子等对测定的影响。此法可用于注射液中氨苄西林钠的测定。 相似文献
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采用丙酮作为溶剂,选用19091N-213型毛细管色谱柱(30 m×0.32 mm i.d.,0.5μm)和氢火焰离子化检测器,以毛细管气相色谱法测定鞋和箱包用胶粘剂中正己烷含量。正己烷的浓度在0~1 000μg/mL与色谱峰面积成线性关系,线性回归方程为A=127 107c 383.26,相关系数r=0.999 1,检出限为0.003μg/mL,用该方法对胶粘剂样品进行测定,测定结果的相对标准偏差为2.8%~4.5%(n=5),加标回收率为96.4%~107.8%。 相似文献
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ICP-AES法测定硼硅酸盐玻璃中的常量及微量元素 总被引:2,自引:1,他引:2
应用电感耦合等离子体原子发射光谱(ICP-AES)法,对硼硅酸盐玻璃中的常量元素Si、Ca、Al、B及微量元素Fe、Ti、Mg进行测定。在优化的工作条件下,各元素的检出限:SiO20.026μg/mL,Ca0.0002μg/mL,Al0.028μg/mL,B0.005μg/mL,Mg0.0002μg/mL,Fe0.006μg/mL,Ti0.005μg/mL。样品测定结果的相对标准偏差(n=6)在0.02%~1.47%之间,加入标准溶液的回收率为93.0%~103.2%。采用该方法对硼硅酸盐玻璃标准样品进行测定,测定值与标准值一致。 相似文献
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建立了以α-羟基-N-甲基乙酰苯胺(HMA)和α-氯代苯并噻唑(CBT)为原料合成农药苯噻草胺的高效液相色谱分析方法,对原料和产物分别进行了定量。研究方法显示:在10.0~200.0、2.0~200.0和5.0~500.0(μg/mL)浓度范围内3种化合物的峰面积与进样量具有良好的线性关系,相关系数分别为r1=0.99992、r2=0.99999和r3=0.99999;方法在3个添加水平考察的平均加标回收率在85.0%~106.0%、88.0%~106.0%和90.0%~103.0%之间;相对标准偏差(RSD)分别为0.96%~0.63%、0.80%~0.47%和0.61%~0.20%;最低检出限LOD=0.02、0.01和0.005(μg/mL)。 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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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
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The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 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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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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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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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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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献