激光剥蚀-电感耦合等离子体质谱(ICP-MS)法测定纯钌中19种杂质元素

建立了激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)法测定纯钌中Mg、Al、Fe、Ni、Cu、Zn、Rb、Rh、Pd、Mo、Ag、Cd、Sn、Ba、Ir、Pt、Au、Pb和Si等19种杂质元素的分析方法。优化了仪器参数,给出了激光能量为60%,剥蚀孔径为110μm,扫描速率为50μm/s,脉冲频率为10 Hz,载气流量为0.74 L/min条件下,信号强度和稳定性最佳。由于钌标准样品难以获得,因此选择用纯钌粉样品,高温高压溶解后,采用ICP-MS法定值所测元素(除硅外)。根据钌粉样品的ICP-MS法定值结果确定了测定元素的相对灵敏度因子(RSF),采用相对灵敏度因子(RSF)对所测结果进行校正,方法准确、快速,检出限为0.007~12.8μg/g,相对标准偏差(RSD)为10%~30%。测定纯钌中杂质元素,结果与ICP-MS法测定的结果吻合。     

193nm ArF准分子激光剥蚀系统高空间分辨率下元素分馏研究

研究了193 nm ArF准分子激光剥蚀系统高空间分辨率下的仪器检出限、ICP质量负载元素分馏、剥蚀深度/束斑直径元素分馏以及基体效应,并在10 μm束斑直径下分析了GSD-1G、StHs6/80-G和NIST612中的微量元素.结果表明,仪器检出限随束斑直径的减小而升高,当束斑直径降低至7 μm时,部分微量元素的仪器检出限为1～10 μg/g.ICP质量负载元素分馏指数与元素第一电离能呈正相关和元素氧化物熔点呈负相关.当剥蚀深度与束斑直径比小于1∶1时,由剥蚀深度/束斑直径引起的元素分馏效应可以忽略不计.基体效应研究表明,50 μm与10 μm激光束斑下基体效应没有明显的差别.以NIST610为校准物质,Ca为内标元素,10 μm束斑直径下GSD-1G、StHs6/80-G和NIST612中的36种微量元素分析结果与定值基本吻合,分析结果与定值基本匹配.综合考虑在10 μm的空间分辨率下,该技术可满足准确分析微量元素的要求.     

基体分离-电感耦合等离子体质谱法测定高纯硒中13种杂质元素

采用基体分离-电感耦合等离子体质谱法（ICP-MS）测定高纯硒中13种痕量杂质元素含量,优化了试验条件.利用二氧化硒在真空条件下升华温度低的特点挥发基体硒,选择合适的内标元素,考察基体效应的影响.结果表明,选择Cs作为待测元素的内标更合适.测定硒残留量小于100 μg/mL的样品,不影响各待测元素.方法检出限为0.007~0.033 μg/g,RSD为5.7%~19%,加标回收率在90.2%~115%之间,可以满足高纯硒中痕量杂质元素含量的测定.     

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)法测定涂层氧化锆颗粒铌层中24种微量杂质元素

本文针对涂层氧化锆颗粒涂层分析需求,建立了LA-ICP-MS分析Nb涂层和Zr基质中24种微量杂质元素测试方法,获得了最佳剥蚀条件(激光束斑44微米、能量密度6J/cm2、剥蚀频率5 Hz);并利用NIST610标样作为外标、Nb和Zr作内标分别校正了Nb涂层及Zr基质层;方法检出限: 1.5μg/g (Fe)、1.16 (Cr)、0.36(Ni),其它21中元素检出限0.01 ~695.72μg/g。该方法成功测定了60件Nb涂层和Zr基质样品中24种微量杂质元素;获得了26种元素深度剥蚀信号vs时间轮廓图,激光剥蚀涂层时间为16～110s;建立了涂层厚度测试方法,利用LA-ICP-MS技术结合环境扫描电镜能谱技术测定了球体涂层的厚度, 获得了准确的LA深度剥蚀率0.3714μm/s,并成功测定了60件样品中涂层的厚度(5.942~40.854 μm),实现了涂层氧化锆涂层成分定量。     

电感耦合等离子体-质谱法测定高纯硫粉末中17种痕量杂质

建立电感耦合等离子体-质谱(ICP-MS)法测定高纯硫粉中Si、P、V、Cr、Mn、Ni、Co、Cu、As、Zn、Zr、Cd、In、Sb、Te、Pb、Bi等17种痕量金属杂质含量的方法。样品用HClO4溶解后挥发硫基体,使样品中杂质元素得到富集,各杂质元素的方法检出限为0.1～50ng/g。方法加标回收率为83%～117%。各杂质元素均为10ng/mL的混合标准溶液平行7次测定的相对标准偏差均小于5%。该方法能够满足纯度为99.999%～99.9999%的高纯硫样品中杂质测定的需要。     

激光剥蚀-电感耦合等离子体质谱法测定土壤中15种微量元素

在土壤标准样品中加入内标元素铼,将其压片后直接进样,将激光聚焦在样品表面下100μm,在以下条件下进行激光剥蚀(LA):(1)剥蚀载气氦气流量为600mL·min-1;(2)剥蚀光斑直径为110μm;(3)剥蚀速率为50μm·s-1。剥蚀后形成的气溶胶进入电感耦合等离子体质谱仪(ICP-MS),对其中15种微量元素(铍、钒、铬、钴、镍、铜、锌、镓、砷、镉、锡、锑、铊、铅、铋)进行测定。采用标准加入法,通过校准曲线外推得到各目标元素的含量。检出限(3s)为0.01～0.08μg·g~(-1);用此方法分析了2个土壤标准样品(GSS-3和GSS-14),除铍、锑和镉,其他元素所得测定值均在认定值的允许不确定度范围内,且相对误差(RE)均不超过10%;对土壤标准样品(GSS-14)重复测定5次,15种元素测定值的相对标准偏差(n=5)均在10%以内。     

离子交换色谱-电感耦合等离子体质谱法测定高纯钛中痕量杂质元素

建立了离子交换色谱-电感耦合等离子体质谱(ICP-MS)测定高纯钛中Mg、Cr、Fe、V、Mn、Co、Ni、Cu、Zn、Sr、Cd、Ba、Tl、Pb等痕量杂质元素分析方法,并对ICP-MS工作参数及条件进行了优化和选择.高纯钛用HF和HNO3溶解后进入离子色谱的阳离子交换柱,经HF(3+97)淋洗后,用HNO3洗脱,洗脱下来的溶液进入电感耦合等离子体质谱检测.方法的检出限在0.00099～0.85 μg/L之间,测定下限为0.0033～2.8 μg/L,各元素的回收率在90%～110%之间.利用本方法对纯度＞99.99%高纯钛样品的杂质元素进行分析,结果表明,其精密度和准确度均满足痕量分析的要求.     

激光剥蚀电感耦合等离子体质谱法中生物样品的元素分馏效应研究

采用213 nm-纳秒激光剥蚀系统对生物基体样品的剥蚀颗粒进行研究,优化了激光剥蚀条件.在剥蚀能量为25%,束斑直径为200 μm,剥蚀速率为20 μm/s,频率为20 Hz,载气为700 mL He + 700 mL Ar时,信号强度及稳定性最佳.以31P为内标元素,最佳剥蚀条件下,考察了56个元素的相对分馏因子.结果表明,生物基体的剥蚀颗粒相较于NIST 610 玻璃标样更大,达到3 μm;生物基体中元素分馏效应相较于玻璃基体小,大多数元素的相对分馏因子达到1.0 ±0.1.探讨了生物基体中元素分馏机理,分析了生物基体相较于玻璃基体剥蚀颗粒大,而相对分馏因子未明显增大的原因.一方面可能是粒径3 μm的颗粒进入电感耦合等离子体后能原子化;另一方面,大的剥蚀颗粒的富集效应相对较小.进一步对分馏效应的影响因素进行研究,发现分馏效应与激光剥蚀能量、激光频率和扫描速率相关,并且与元素的氧化物沸点负相关,与氧化物键能和电离能正相关.     

微波消解电感耦合等离子体质谱法测定UHMWPE中铝、钙、钛

建立微波消解样品、电感耦合等离子体质谱（ICP-MS）法同时检测外科植入物用超高分子量聚乙烯（UHMWPE）中铝、钙、钛3种杂质元素的分析方法。取0.50 g样品，加入5 mL硝酸和1 mL过氧化氢，于180℃微波消解15 min，以钪（45Sc）为内标，用ICP-MS法同时测定外科植入物用UHMWPE中杂质元素铝、钙、钛的含量。该方法对铝、钙、钛元素的测定具有良好的线性关系，相关系数均不小于0.999 6，检出限为0.10～0.14 mg/kg，样品测定结果的相对标准偏差为1.2%～3.6%(n=7)，样品加标回收率为97.3%～101.3%。该方法适用于测定UHMWPE中杂质元素含量。     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定硅石中五种杂质元素

采用微波消解溶解样品,建立ICP-MS法测定硅石中锰、铜、钒、钛、铬5种杂质元素的方法。探讨了溶解样品及消除干扰的最佳方式,选用Sc(10μg/L)为内标,动态反应池(DRC)模式进行测定。方法检出限为0.1mg/kg(51V)~1.66 mg/kg(47Ti),加标回收率在88.6%~109%,相对标准偏差均小于3%。方法快速准确,精密度好,检出限低,适合硅石中5种杂质元素的测定。     

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.     

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%).     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

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.