微波消解–电感耦合等离子体质谱法测定酱卤肉中铬、砷、镉、铊、铅

建立微波消解–电感耦合等离子体质谱法测定酱卤肉中铬、砷、镉、铊、铅5种元素含量的检测方法。采用微波消解法处理酱卤肉样品,对预处理条件和仪器工作参数进行了优化,以内标校正法降低基体影响。结果表明,铬、砷、镉、铊、铅5种元素的质量浓度在0.1~50.0 μg/L范围内与质谱响应值具有良好的线性关系,相关系数均大于0.999,方法检出限为0.2~6.2 μg/kg。在3种加标浓度水平下平均回收率为72.4%~113.5%,测定结果的相对标准偏差为3.1%~7.7%(n=6)。该方法简便,快速,高效,准确,可为酱卤肉中铬、砷、镉、铊、铅的测定提供技术支持。     

微波消解-ICP-MS测定中药材中5种有害元素的研究

比较了密闭容器消解、微波消解两种消解方法的消解效果,并建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定中药材(CTM)中铜砷镉汞铅等5种有害元素含量的分析方法,对各元素的线性关系良好(r=0.9998~1.0000),检出限为0.005μg/g(Hg)~0.056μg/g(Cu),标准物测定回收率均在84.2%~101%,因其低检出限、高灵敏度,本方法能满足中药材样品质量控制中5种有害元素的测定要求。另外利用本方法对24种中药材中5种有害元素含量进行了测定,结果表明中药材中有害元素含量超标问题严重,必须在生产过程中予以重视。     

电感耦合等离子体质谱法测定金银花中6种有毒元素

建立电感耦合等离子体质谱法同时测定金银花中铅、镉、铬、镍、铜、砷6种有毒元素含量。采用微波消解法进行前处理,以钪、铟、铋3种元素作为内标物,用电感耦合等离子体质谱法对50批金银花样品中铅、镉、铬、镍、铜、砷6种有毒元素含量进行测定,以内标法定量,并应用SPSS软件对测定值进行统计学分析。6种有毒元素的质量浓度在0~300μg/L范围内线性良好,相关系数均不小于0.9997。6种有毒元素的检出限为0.003~0.020 mg/kg,样品加标回收率为80.0%~111.0%,相对标准偏差为0.71%~3.82%(n=6)。50批金银花样品中共计有14批样品有毒元素含量超出2015年版《中华人民共和国药典》规定,超标率为28%。聚类分析将50批样品分为3大类。该方法操作简单,灵敏度高,专属性好,可准确快速地同时测定金银花中多种有毒元素含量,可作为中药材品质及安全性监管的技术手段。     

ICP–MS法测定食品接触纸制品中铬、镍、砷、镉、铅、汞

建立电感耦合等离子体质谱法(ICP–MS)测定食品接触纸制品中铬、镍、砷、镉、铅、汞6种重金属含量的方法。样品经微波消解处理后用ICP–MS进行测定,内标法定量。在优化实验条件下,测定汞元素的线性范围在0~10μg/L之间,测定铅、镉、铬、镍、砷元素的线性范围在0~100μg/L之间,相关系数均大于0.999。各元素的检出限为0.001~0.1 mg/kg,加标回收率为89.3%~116.0%,测定结果的相对标准偏差为3.5%~7.9%(n=6)。该方法样品处理简单,检测灵敏度高,适用于食品接触纸制品中铬、镍、砷、镉、铅、汞的检测。     

氟化铵辅助消解-电感耦合等离子体质谱法测定热熔胶中7种微量元素

建立了氟化铵辅助消解-电感耦合等离子体质谱法(ICP-MS)测定热熔胶中7种微量元素(铬、镍、砷、硒、镉、汞、铅)的方法。用由60%(体积分数)硝酸溶液6 mL和12.66 mol·L~(-1)氟化铵溶液0.50 mL组成的消解体系在185℃下微波消解0.300 0 g热熔胶样品20 min。在平板控温加热器上于120℃赶酸3 h,得到的消解液用水定容至50 mL,按优化的ICP-MS条件测定,内标元素~(115)In用于定量。结果显示:7种元素的质量浓度与其与内标元素铟的信号强度的比值在一定的范围内呈线性关系,检出限(3s)为0.005～0.029 mg·kg~(-1);对实际样品进行3个浓度水平的加标回收试验,所得回收率为86.3%～106%,测定值的相对标准偏差(n=5)为1.8%～11%。方法用于5个实际样品的分析,在5个样品中均检出了铬和镍,3个样品中检出了铅,3种元素的检出量均低于YC/T 187-2004规定的限值;将该方法与YC/T 316-2014进行比对,在95%置信水平下,铬和镍的t值均小于临界值t_(0.05,4),铅的t值小于临界值t_(0.05,2),3种元素p值均大于0.05,2种方法无显著性差异。     

X射线荧光光谱法同时测定涂料中的铅、铬、硒和钴

提出了用X射线荧光光谱法同时测定涂料中有害重金属铅、铬、硒和钴的一种新的测试方法. 考察了样品量不同和样品粒度不同对待测元素测试结果的影响. 选用不含待测元素的新鲜涂料作为基体物质制备标准样品, 较好地消除了基体的影响. 各待测元素在50～1000 mg/kg的范围内, 均呈线性关系;Pb、 Cr、 Se、 Co的检出限分别为3.6、 1.2、 0.5及1.5 mg/kg;方法精密度和仪器精密度的相对标准偏差分别低于1.3%和0.50%;用于实际样品测得的结果与电感耦合等离子体原子发射光谱法法测得的结果基本一致.     

ICP-OES法同时测定功效牙膏中10种元素

采用ICP-OES同时测定功效牙膏中的铅、镉、汞、砷、铜、锌、钾、锶、银、钛等10种元素。结果表明,在HNO3-H2O2-HF体系下,采用微波消解方法,对牙膏样品进行完全消解。通过优化仪器条件参数,实现对功效牙膏中的铅、镉、汞、砷、铜、锌、钾、锶、银、钛等元素的ICP-OES法同时测定。钛、钾元素质量浓度在5.0~100.0 mg/L,锶、锌元素质量浓度在1.0~50.0 mg/L,铅、镉、汞、砷、铜、银元素质量浓度在0.1~2.0 mg/L范围内时,方法有良好的线性关系,相关系数均大于0.992。样品中各元素的加标回收率在93.0%~109.0%。     

电感耦合等离子体质谱法测定地龙药材中铅、砷、汞、镉、铜元素的残留量

建立电感耦合等离子体质谱法(ICP-MS)测定不同产地和批次地龙药材中铅(Pb)、砷(As)、汞(Hg)、镉(Cd)、铜(Cu)5种重金属元素的含量.采用微波消解进行样品前处理,结果表明:5种重金属元素的线性关系良好(r≥0.999 6),平均回收率在92.8%~95.2%范围内,方法的检出限在0.001 0~0.092 mg/kg范围内.方法灵敏度高,重复性好,方法准确.不同产地和批次的样品中5种重金属元素均有检出.地龙药材中Pb、As、Hg、Cd、Cu这5种重金属元素需要重点监控.     

电感耦合等离子体质谱法测定接装纸中砷、钼、镉、铊和铅

建立了一种同时测定接装纸中砷、钼、镉、铊和铅5种元素的电感耦合等离子体质谱分析方法,实验采用微波消解前处理样品,HNO3-H2O2-HF混合体系作消解剂。方法的加标回收率94.79%~114.6%,检出限0.002~0.18μg/L,相对标准偏差1.1%~4.4%(n=5),线性相关系数0.9996~1.000。用所建立的方法测定了17个牌号接装纸中砷、钼、镉、铊和铅的含量,结果发现:砷、钼、镉、铊和铅在接装纸中的含量较低,其平均值均低于1.0μg/g,接装纸中钼和铊两种元素的变异较大,镉的变异最小,其变异系数分别为98.5%、151.1%,53.0%。     

微波灰化-电感耦合等离子体质谱法测定电泳涂料中15种金属元素

建立电感耦合等离子体质谱法测定电泳涂料中15种金属元素的分析方法。以微波灰化方式处理样品,采用碰撞诱导解离(CID)-动能歧视(KED)联合模式消除质谱干扰,实现高浓度元素和痕量元素的同时检测;采取气体稀释模式降低基体干扰并减少高浓度元素对质量检测器的损害。Na、Mg、Al、K、Ca、Fe和Zn质量浓度在0.01~10.0mg/L范围内,Cu、Mn、Ni、Co、Cr、Cd、Ba和Pb的质量浓度在1.0~1000.0 g/L范围内线性关系良好,线性相关系数为0.9991~0.9999,方法检出限为0.3~23μg/kg。测定结果的相对标准偏差为0.6%~3.2%(n=6),样品加标回收率为91.5%~107.0%。该方法可用于汽车电泳涂料中金属元素的检测。     

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%.     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.