流动注射氢化物发生电加热石英管原子吸收光谱测定测血清硒

采用自控电热消器消化血清,消化液经流动注射氢化物发生－电加热石英管－原子吸收光谱法测定血清硒。该方法的检 为0．45mg.ml^-1,同一血样8次测定相对标准偏差为3．59％,用该法测定了冻干牛血清标准物质和牛血清标准物质,测定结果均落在标准物质的不确定度范围内。方法准确、简便,灵敏,已用于临床血清硒样本的测定。     

石墨炉原子吸收光谱法测定大鼠血清中硒

通过考察不同基体改进剂效果，提出了以硝酸锶和硝酸钯做为混合基体改进剂。建立了用石墨炉原子吸收法测定牛血清和大鼠血清中痕量硒的分析方法。线性范围为0-120ng/mL，硒的检出限为0．095ng／mL，方法用于标准牛血清测定。结果与标准值基本吻合，大鼠血清测定标准加入回收率为102％。     

高压罐消解-氢化物发生原子荧光法测定食品中的硒

利用高压罐消解-氢化物发生原子荧光法测定食品中的硒.在4mol/LHCl介质中利用AFS-2201双道原子荧光光度计对国家一级标准物质奶粉进行测定.测定硒元素曲线的浓度在0～100.0 ng/mL之间呈良好的线性关系,相关系数为0.9998,其检出限为0.47 μg/L.实验结果表明本方法可用于食品中硒含量的测定和监控.     

用超声波加快硒-邻苯二胺的络合与萃取测定硒(Ⅳ)

邻苯二胺是常用的测定硒的络合剂,Ariyoshi等人曾以邻苯二胺为络合剂用紫外光谱法测定微量硒,侯家麟等用相同的方法测定了亚硒酸钠片中硒的含量,其原理是:邻苯二胺与亚硒酸发生络合反应生成3,4-苯并-1,2,5-重氮苤硒脑,再以甲苯萃取,用光度法测定萃取液。我们试用超声波作用使络合和萃取一步完成,该方法尚未见文献报道。     

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硒

环境样品经硝酸-过氧化氢-氢氟酸体系微波消解,利用自制雾化器采用氢化物发生-电感耦合等离子体原子发射光谱法测定其中的痕量硒。选择硒的分析谱线为196.090nm。硒的质量浓度在32μg·L-1以内与其发射强度呈线性关系,方法的检出限(3S/N)为0.71μg·L-1。方法应用于国家标准物质中硒的的测定,测定值与认定相符,加标回收率在85.8%~102%之间,测定值的相对标准偏差(n=6)在0.38%~2.3%之间。     

断续流动氢化物发生原子荧光法测定富硒食品中的微量硒

建立了断贯流动氢化物发生原子荧光法测定富硒食品中微量硒的方法。样品用硝酸高氯酸混酸消化，在优化的实验条件下，标准曲线的线性范围为0-100μg/L，相关系数为0.9999。检测限0.06545μg/L。应用于测定鸡蛋，富硒米和富硒盐中微量硒的测定。回收率分别为90.6%,98.5%和104.3%。     

微波消解–原子荧光光谱法测定植物样品中的砷和硒

建立微波消解-原子荧光光谱法测定植物样品中砷和硒的含量。微波消解后残留的有机颗粒和硝酸等会对测定结果造成影响,因此需要将硝酸除尽。在驱除硝酸过程中加入高氯酸,加热至溶液冒白烟,避免硒挥发损失。该方法砷、硒的检出限分别为6.8,4.0 ng/g(稀释因子40),测定结果的相对标准偏差分别为3.65%,3.52%(n=12),加标回收率分别为94.5%~104.6%,92.2%~98.9%。经过国家一级标准物质验证,该方法准确可靠。     

流动注射氢化物发生-原子吸收光谱法 测定镍基合金中的硒和锡

建立了流动注射氢化物发生-原子吸收光谱法测定高温镍基合金中痕量硒和锡的方法。样品用HNO3和HF经微波消解后,制成以EDTA作掩蔽剂的碱性溶液(pH12～13),用标准加入法测定。方法测定硒和锡的检出限分别为1.0μg     

卡尔菲休滴定仪测定液体石油产品中水含量

对运用卡尔菲休滴定仪库仑法测定液体石油产品中微量水的简单原理、分析方法的建立与分析流程进行了论述.实验结果表明,该方法测定结果的相对标准偏差为0.66%～1.30%(n=8),用该方法测定3种标准物质,其相对误差不大于2%.该方法分析快速、简便,适用于含有醇类、无机含氧弱酸特殊样品的测定.     

微波消解试样-原子荧光光谱法测定土壤中硒碲

应用HG-AFS法及微波加热试样消解法测定了土壤中硒和碲的含量,对试样消解参数、仪器工作条件及氢化物发生反应条件等作了试验并讨论.该方法测定硒及碲的检出限均为0.01μg·g-1,荧光强度与硒及碲的质量浓度在5～100μg·L-1及0.5～10μg·L-1范围内呈线性关系.应用此方法分析了3个土壤试样,测定值的相对标准偏差(n=6)均小于5%.用标准加入法作了回收试验,硒的回收率在92.0%～102.6%之间,碲的回收率在90.1%～98.8%之间.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

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.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.