ICP-AES测定粗银粉及银阳极板中Se、Sb等杂质元素

研究用ICP-AES同时测定粗银粉及银阳极板中Se、Sb、Te、Pb、Bi、Au、Fe、Cu和Pd杂质元素的方法.试验以酒石酸作掩蔽剂,突出解决了溶样过程中AgCl对杂质元素的吸附损失,确定了合适的分析线和折衷的仪器分析条件,9个被测元素的检出限为0.002～0.008μg/mL,相对标准偏差(n=11)为0.50%～3.6%,加标回收率为98.57%～100.5%,可用于粗银粉和银阳极板中杂质元素的测定.     

ICP—AES法测定对苯二甲酸中微量杂质

利用挥发操作技术,使基体对苯二甲酸与杂质分离,富集后的杂质元素,经硝酸溶解后用ICP-AES法测定,测定下限为1μg·g~(-1),回收率为97%～108%,相对标准偏差为1.4%～10.5%,方法具有灵敏、准确、操作简便的特点.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铅锭中11种杂质元素

研究了用酸分解试样后不需分离基体直接用电感耦合等离子体原子发射光谱(ICP-AES)法测定铅锭中银、铜、铋、砷、锑、锡、锌、铁、镉、镍、铊11种杂质元素的方法。优化了样品前处理条件及仪器检测条件。方法的检出限为0.0012～0.0168μg/mL,回收率为89%～110%,RSD为2.3%～5.0%。方法简便快速,检出限低,精密度和准确度能满足铅锭中杂质元素的检测要求,具有较强的实用性和可操作性,可用于铅锭中杂质元素的测定。     

萃取分离 ICP-AES 法测定含铪铀中微量杂质元素

用盐酸-硝酸-氢氟酸溶解含铪的铀试样,以磷酸三丁酯为萃取剂,分离铀、铪与待测杂质元素.用 ICP-AES 法同时测定了试样中钼、钨、铁、硼、锰、铍、铜、镁、钙、铝和镍等11种杂质元素的含量.将 0.0900 g～0.1100 g 试样制成 6 mL 溶液时,各杂质元素测量范围为 1.0×10-3%～1.0×10-1%,回收率在 94%～105% 之间,相对标准偏差优于 10%.     

ICP—AES法直接测定高纯氧化钐中14个稀土杂质元素

本文采用ICP-AES技术,对纯度为99.95%氧化钐中14个稀土杂质元素的直接测定进行了研究.对分析线的选择,工作功率,载气流量,观测高度,进样浓度等条件进行了试验.本法条件下,各分析元素的相对标准偏差均小于8%,标准加入回收率介于92%～108%之间.并对实际样品进行了测定、结果满意.     

电感耦合等离子体原子发射光谱法和电感耦合等离子体质谱法检测药品中元素杂质的研究进展北大核心CSCD

随着国际人用药品注册技术协调会(ICH)Q3D元素杂质指导原则的实施及中国加入ICH,中国于2020年1月执行ICH Q3D,药物中元素杂质逐渐成为人们的关注热点.电感耦合等离子体原子发射光谱法(ICP-AES)和电感耦合等离子体质谱法(ICP-MS)是两种美国药典(USP)‹233›推荐的元素杂质的检测方法,并成为多元素杂质检测方法的替代方法.概述了ICH Q3D规定元素杂质及其来源,总结了两种方法的主要优点、局限性及样品制备方法,涵盖了近年来文献中报道的主要用于活性药物成分(API)、原料和药物的应用,讨论了在采用ICP-AES和ICP-MS分析药品过程中的干扰.目前采用ICP-AES和ICP-MS检测药物中的元素杂质已经是一种趋势,综述(所引文献75篇)可为元素杂质检测方法的开发提供一定的参考.     

电感耦合等离子体原子发射光谱法测定高纯钛中痕量元素

应用电感耦合等离子体原子发射光谱(ICP-AES)法测定高纯钛中14项杂质元素,并对其最佳测定条件进行了试验.采用两点法制备工作曲线.试样溶于盐酸和硫酸混合酸中,滴加过氧化氢使钛氧化至4价.将试液蒸干使钛以二氧化钛状态沉淀析出,加入稀硝酸后将其过滤除去.在滤液中进行各杂质组分的ICP-AES测定,所测14项元素的检出限(3S)在5×10-4～1.5×10-2 mg·L-1范围内,回收率在97.5%～113.4%之间.     

新型D-238树脂色层分离-ICP/AES法测定4N光学级La_2O_3中Co、Cr、Cu、Fe、Mn、Ni、Pb和V

本文采用新型D-238树脂,使待测元素与基体La分离。用6mol/L HNO_3解脱非稀土杂质,ICP-AES法同时测定4N光学级La_2O_3中8个痕量非稀土杂质。方法的检出限为0.2～2.8μg/g,相对标准偏差<8%。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铂金材料中杂质元素

建立了微波消解-电感耦合等离子体原子发射光谱（ICP-AES）法同时测定铂饰品国家标准物质中金、铜、铱、钴、钯、铑、钌7种杂质元素含量的方法。方法中7种元素的检出限为：钯与钌〈0.0001%,其它元素〈0.000 62%。经与国家标准物质认定值比对,结果满意。稀释系数95.5%-104.7%。方法测定结果与标准样品认定值一致,可满足铂金材料中杂质元素检测。     

电感耦合等离子体原子发射光谱（ICP-AES）法测定高纯氧化铟中7种杂质元素

采用电感耦合等离子体原子发射光谱(ICP-AES)法测定高纯氧化铟中杂质元素Al、Cd、Cu、Fe、Pb、Tl和Zn等的含量。使用盐酸(1+1)溶解高纯氧化铟试样,基体铟的干扰采用基体匹配法消除,被测元素之间没有光谱干扰。对方法进行加标回收实验和精密度实验,方法加标回收率在92.2%～110%,测得结果的相对标准偏差在0.57%～5.8%,可以满足高纯氧化铟中Al、Cd、Cu、Fe、Pb、Tl和Zn等杂质元素含量的测定要求。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.