石墨炉原子吸收光谱法测定精对苯二甲酸产品中7种金属杂质的含量

采用石墨炉原子吸收光谱法测定精对苯二甲酸中钛、钼、铬、镍、钴、锰和铁等7种金属杂质的含量。石墨炉灰化温度为750℃,灰化时间为45min,采用硫酸(1+1)溶液溶解残渣。铁和镍的质量浓度在20μg·L-1以内,钴、锰、铬、钼和钛质量浓度在120μg·L-1以内呈线性。各元素的检出限(3S/N)在0.5~1.6μg·L-1之间,加标回收率在92.0%~105%之间,测定值的相对标准偏差(n=6)小于5%。采用本法测定样品中钴、锰和铁的含量,结果与标准方法所测得结果相吻合。     

原子吸收光谱法测定铸铝铜合金拉伸断口毫克级样品中主成分

研究了铸铝铜合金拉伸断口毫克极样品中主成分铜、锰、镉的火焰原子吸收光谱法（FAAS）和钛的石墨炉原子吸收光谱法（GFAAS）。其中铜、锰、镉、钛的相对标准偏差分别为0.53%,0.79%,2.57%,5.5%。其加标回收率分别为95%,95%-97%,101%,90%。通过对铸铝铜合金拉伸断口的化学分析研究,发现铜偏析是该合金位伸断裂的主要因素。     

电感耦合等离子体原子发射光谱法同时测定不锈钢中的11种元素

建立电感耦合等离子体原子发射光谱法同时测定不锈钢中硅、锰、磷、铬、镍、钼、钴、钒、钛、铜、铝11种元素含量的方法。样品采用盐酸溶液溶解,硝酸氧化,在优化的实验条件下,用电感耦合等离子体原子发射光谱法测定各元素含量。磷的质量浓度在0～5 mg/L范围内,钛、铝、钴的质量浓度在0～10 mg/L范围内,钒的质量浓度在0～15mg/L范围内,铜、硅、钼的质量浓度在0～20 mg/L范围内,锰的质量浓度在0～50 mg/L范围内,镍的质量浓度在0～80 mg/L范围内,铬的质量浓度在0～100 mg/L范围内与光谱强度呈良好的线性关系,相关系数均大于0.998,方法检出限为0.002～0.035 mg/L。测定结果的相对标准偏差均小于2%(n=6),加标回收率为97.9%～105.6%.该方法快速、准确,适用于实际生产中不锈钢样品的批量检测。     

原子吸收光谱法测定水生生物体内铜、锌、镍、铬、铅、镉

用硝酸-高氯酸体系消解螺蛳和水葫芦样品,采用火焰原子吸收光谱法测定铜、锌、镍、铬,用石墨炉原子吸收光谱法测定铅、镉。铜、锌、镍、铬、铅、镉的检出限分别为0.328、0.126、0.271、0.416、0.006 64、0.001 15 mg/kg,线性相关系数不小于0.999 0,测定结果的相对标准偏差为1.1%~3.7%,加标回收率为86.0%~94.2%。     

ICP-AES法测定稀土磁性材料中微量铬、镍和钛

研究了采用电感耦合等离子体原子发射光谱(ICP-AES)测定稀土磁性材料中微量铬、镍和钛的分析方法。确定了样品的溶解方法和待测元素的分析线,对基体元素和共存元素的干扰影响进行了考察,采用基体匹配法克服了基体效应。该方法测定结果与火焰原子吸收光谱法测定结果相一致。铬、镍、钛的检出限分别为0.001 4、0.002 8、0.000 5μg/mL,测定结果的相对标准偏差小于7.0%(n=8),方法的加标回收率为97.0%~104.7%。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定高铼酸钾中的19种杂质元素

建立了一种用稀盐酸溶解样品,标准工作溶液中匹配钾,电感耦合等离子体原子发射光谱(ICP-AES)法测定高铼酸钾中19种杂质元素的方法。在选定的仪器工作条件下,样品加标回收率分别为:钠94.4%~101%、钙98.8%~102%、铝98.1~102%、镁95.8%~99.1%、钴98.4%~101%、钼97.3~103%、钛97.6%~102%、钒96.6%~106%、锆96.2%~97.7%、铬97.8~101%、铜98.1%~108%、铁92.9%~104%、锰95.5%~98.4%、镍93.6%~101%、钯93.3%~101%、铅96.5%~103%、锌95.2%~103、铂95.9%~99.9%、铑94.5%~96.3%;方法相对标准偏差(RSD)(n=7)分别为:钠2.0%~5.5%、镁1.1%~3.5%、铝0.9%~2.5%、钙1.5%~7.3%、钴1.1%~3.1%、钼0.9%~4.5%、钛1.0%~2.8%、钒1.6%~4.0%、锆1.4%~3.6%、铬0.77%~4.6%、铜0.74%~1.8%、铁1.3%~3.8%、锰1.1%~2.0%、镍0.99%~5.0%、钯1.1%~2.4%、铅1.3%~9.1%、锌0.80%~6.7%、铂1.2%~10%、铑0.78%~8.6%。方法简便、快速、准确,满足生产分析要求。     

微波消解-电感耦合等离子体质谱法测定高纯五氧化二钒中15种杂质元素

高纯五氧化二钒样品在硝酸-氢氟酸(4+1)混合液中经微波消解处理,采用电感耦合等离子体质谱法测定样品溶液中15种杂质元素(钛、硅、铝、铬、镍、铜、铅、砷、磷、铁、锰、钙、镁、钾、钠)的含量。采用内标法消除基体的影响。方法的检出限(3s/k)在0.03~0.89μg·L-1之间。方法的加标回收率在90.0%~113%之间,相对标准偏差(n=8)小于5.0%。五氧化二钒5号样品中8种杂质元素的测定值与石墨炉原子吸收光谱法进行核对,测得结果互相符合。     

石墨炉原子吸收光谱法快速测定天然矿泉水中铬镍和银

研究了快速程序升温石墨炉原子吸收光谱法用于测定天然矿泉水中铬、镍和银。为提高分析速度，该法在升温程序中删去了灰化步骤，缩短了灰化时间，整个升温程序只需22～23s，远快于常规石墨炉原子吸收光谱法(80-90s)。铬、镍和银的回收率分别为94．0％～103．0％、98．5％-104．0％和95．0%-104．0％，符合测定要求。     

新生儿脐血清微量元素测定及与生长发育关系研究

应用电感耦合等离子体发射光谱法测定也３３名新生儿脐血清中１７种微量元素（铁、铜、锰、锌、钴、钼、硒、铬、锡、钒、硅、镍、镉、铅、锶、钛、铝）及３种常量元素（钙、磷、镁）的含量。结果表明,新生儿脐血清微量元素性别分布接近,仅女婴血清铬、钒高于男婴,但地区差异明显,城镇新生儿脐血清中锰、锌、锶、钛、钙较高,而钼、硒、铬、铝较低。多元回归分析显示,血清元素铁、锰、锌、硒、硅、锶、钙被引人新生儿体重和发育     

ICP-AES测定钢铁中多元素的通用前处理法

通过探讨溶解酸与钢铁化学成分、金相组织之间的关系,提出了一种简单的电感耦合等离子体原子发射光谱(ICP-AES)测定钢铁中多元素的通用前处理方法。用高氯酸溶解并冒烟分解钢铁样品,稀盐酸或过氧化氢还原铬(Ⅵ),ICP-AES测定钢铁中磷、锰、铬、钼、镍、钒、铜、铝、钛、钴、镁、铈等常见元素;该方法与硝酸-盐酸溶解酸方法有良好的兼容性。     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.