电感耦合等离子体原子发射光谱法(ICP-AES)测定富铼渣中的铼

建立了电感耦合等离子体原子发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明:于盐酸(10%)介质、227.525nm分析线处,铼测定浓度在0.20~50.00μg/mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%~3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和加标回收率分别为酸密闭消解法6.46×10-10μg/mL,0.69%~1.1%和99.95%~100.1%,碱熔解法6.49×10-10μg/mL,0.69%~1.1%和99.96%~100.3%。     

四酸密闭消解-电感耦合等离子体质谱(ICP-MS)法测定铀矿中的铼和钪

建立一种准确测定铀矿中铼和钪含量的方法,为铀矿中伴生元素的分析与研究提供数据支持、对探勘铼钪矿实现战略资源合理利用化有着重大意义。采用氢氟酸-硝酸-盐酸-高氯酸四酸溶解样品,利用密闭聚四氟乙烯坩埚-电热板加热方式来测定铼钪,建立了电感耦合等离子体质谱(ICP-MS)法测定铀矿中铼和钪的方法,探讨了分解方法、称样量、酸用量、溶样温度及时间、基体干扰、内标选择的影响。实验结果表明：酸溶分解结果准确性高于碱溶分解,3 mL HF、4 mL HNO3、2 mL HCl和1 mL HClO4为最佳消解体系,0.05 g~0.10 g、10 mL~12 mL为最佳称样量和酸用量,闭盖160 ℃、开盖190 ℃ 18 h为最佳溶样条件,选择碰撞气流速为3.0 mL/min,稀释气流速为0.8 L/min降低基体干扰,In作为内标能够达到测试要求。该方法操作简单同时将铼钪测试,其中铼和钪的检出限分别为0.006 mg/kg和0.366 mg/kg;铼准确度在92.9%~98.4%,相对标准偏差在2.4%~5.7%,钪准确度在93.5%~98.2%,相对标准偏差在1.6%~6.2%;铼加标回收率为87.2%~93.8%,钪加标回收率为90.7%~92.3%,检出限低,精密度良好,灵敏度低满足铀矿中铼和钪的分析要求。     

火焰原子吸收光谱法测定变形高温合金GH4169中痕量钾、钠

建立火焰原子吸收光谱法测定变形高温合金GH4169中痕量钾、钠。称取0.5000 g样品,用8 mL混合酸(硝酸-氢氟酸-水的体积比为1∶1∶1)溶解,加入5 mL丙酮以提升灵敏度,在选定的仪器工作条件下进行测定。结果表明,钾元素采用样品标准加入法,钠元素采用镍基体匹配标准曲线法,溶液中钾、钠的质量浓度在0~500μg/L范围内与吸光强度呈良好的线性关系,相关系数分别为0.9980、0.9983,钾、钠的检出限分别为0.000098%、0.000058%。钾、钠9次重复测定结果的相对标准偏差分别为2.8%~7.0%、2.2%~7.9%,加标回收率分别为97%~110%、95%~107%。该方法满足变形合金GH4169中钾、钠含量的检测要求。     

电感耦合等离子体发射光谱法(ICP-AES)测定富铼渣中的铼

建立了电感耦合等离子体发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明：于盐酸(10%)介质、227.525 nm分析线处,铼测定浓度在0.20～50.00 μg/mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%～3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和加标回收率分别为酸密闭消解法6.46×10-10 μg/mL、0.69%～1.1%和99.95%～100.06%,碱熔解法6.49×10-10 μg/mL、0.69%～1.1%和99.96%～100.31%。     

电感耦合等离子体发射光谱法测定富铼渣中的铼

建立了电感耦合等离子体发射光谱法测定富铼渣中铼含量的方法。对样品的酸密闭消解、碱熔解和测定铼的条件进行了研究。结果表明：于10%盐酸介质、227.525 nm分析线,铼测定浓度在0.20～50.00 μg/ mL线性良好;两种样品分解方法测得铼结果吻合,用于富铼渣样品中1.85%～3.66%铼含量的测定,检出限、相对标准偏差(RSD,n=22)和回收率分别为酸密闭消解法6.46×10-10 μg/mL、0.689%～1.065%和99.95%～100.06%,碱熔解法6.49×10-10 μg/mL、0.691%～1.059%和99.96%～100.31%。     

电感耦合等离子体质谱法测定重晶石中的微量元素

重晶石样品(0.200 0~0.250 0g)经氢氟酸(6mL)、盐酸(3mL)和硝酸(1mL)溶样,蒸干,最后用盐酸(1+3)溶液4mL溶解残渣,加水定容至100mL。采用电感耦合等离子体质谱法测定其中锶、铝、钙、镁、钾、钠、铜、铅、锌等9种微量元素的含量。用一级标准物质(GBW07811、GBW 07814、GWB 07812)绘制标准曲线,以铼为内标物。方法的检出限在2.2×10-7~1.51×10-6之间。方法用于实样分析,测定值的相对标准偏差(n=10)在2.2%~3.8%之间。应用此方法分析了4种重晶石标准物质(GBW 07813、GBW 07815、GBW 07816、GBW 07817),所得测定值与认定值相符。用标准加入法做方法的回收试验,测得回收率在90.0%~120%之间。     

铼(Ⅶ)催化Na_2TeO_4与SnCl_2氧化还原反应及其应用研究

研究了在硫酸介质中,铼催化碲酸和氯化亚锡的氧化还原反应速率,建立了催化动力学光度法测定痕量铼的方法,优化了高铼酸钾-柠檬酸-碲酸钠-聚乙烯醇-二氯化锡反应的实验条件;测定了催化反应的表观活化能Ea'=15.87 kJ/mul和表观速率常数K'=1.28×10-3s-1,铼含量在0.004～1.2μg/mL范围内服从比尔定律.回归方程Y=0.129 cμg/10mL+0.016 3;相关系数r=0.997;应用于钼灰、钼精砂等矿样中铼的测定,测定结果的RSD≤±5%(n=5),加标回收率为98.0%～100.1%(n=5),符合实用性要求.     

电解-电感耦合等离子体原子发射光谱(ICP-AES)法测定铼酸铵中铼

建立了一种测定铼酸铵中铼主品位含量的全新检测方法。确定了电解电流、电解液成分和含量、电解液温度、搅拌速度、电解时间等最佳实验条件,即:在室温、不搅拌、4.0 A电流、5 g/L硫酸溶液、20 g/L硫酸铵溶液和电解时间为7.6 h条件下进行检测。干扰实验表明,铼酸铵样品中铅、砷、汞、铁等共存元素对铼的电解沉积影响可忽略;铜的影响可通过扣杂的方式予以消除。将实验方法用于铼酸铵实际样品中铼的测定,测得结果与四苯砷氯盐酸盐重量法基本一致,相对标准偏差(RSD,n=5)小于0.14%,回收率为99.2%~102%。方法准确、可靠,能满足日常分析要求。     

高含量铼的紫外分光光度法测定研究

采用紫外分光光度法测定了高含量铼样品中的铼.研究了过氧化氢溶解和氢氧化钠碱熔对钨铼、钼铼合金样品的不同前处理过程,确定了铼的最佳测定条件为:在50 mL容量瓶中加入40 mL氢氧化钠(50％),4 mL盐酸羟胺(1％),反应30 min后在波长300 nm处测定.测定了钨铼、钼铼合金以及高铼酸铵中的铼,相对标准偏差(n...     

浊点萃取-同步荧光法测定痕量荧光增白剂VBL

根据表面活性剂和荧光增白剂之间的相互作用,提出了浊点萃取-同步荧光法测定纸制样品中痕量荧光增白剂VBL的新方法。研究发现,相比于传统荧光发射光谱,当最佳波长差为30 nm时,VBL在402 nm处有一强度高、峰型窄的同步荧光峰。体系的相对荧光峰强度与VBL的浓度在0.001~0.053μg/mL范围内呈良好的线性关系,相关系数0.9993,线性方程为IF=10729.48ρ(μg/mL)+42.36,检测限(3S/K)为8.415×10-4μg/mL。方法用于样品测定,回收率在90.6%~102%之间,相对标准偏差在1.3%~5.2%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.