电感耦合等离子体质谱法同时检测红枣中铅、砷、镉、汞、铜、锌和16种稀土元素

为了研究哈密、若羌和和田红枣中铅、砷、镉、汞、铜、锌和16种稀土元素的含量情况,了解红枣重金属及稀土元素摄入的风险,建立同时检测红枣中铅、砷、汞、铜、锌和16种稀土元素的方法。红枣样品用微波消解法进行样品前处理,以电感耦合等离子体质谱法测定红枣中铅、砷、镉、汞、铜、锌和16种稀土元素的含量。各元素校准曲线的相关系数均大于0.999 0,检出限为0.01~0.05μg/L。加标回收率为92.1%~105.2%,测定结果的相对标准偏差为1.2%~3.6%(n=6)。用该方法测定苹果标准物质(GBW 10019),测定值与标准值一致。该方法适用于红枣类样品中多元素污染物快速检测及风险评估,红枣样品分析结果表明铅、砷、镉、汞、铜和稀土元素在3种红枣中的含量较低,风险监测数据表明红枣中存在重金属铅、镉摄入性风险。     

测定川芎中有害金属元素的三种样品前处理方法的比较试验

用3种不同的样品前处理方法,即①常规湿法酸消解法、②微波加热酸消解法及③干灰化法分别对川芎样作前处理溶解,用石墨炉原子吸收光谱法(GF-AAS)测定试液中铅、铜和镉的含量,用氢化物发生-原子荧光光谱法(HG-AFS)测定试液中砷和汞的含量。结果表明:用方法①及方法③处理样品所得溶液中,铅、铜和镉的回收率在83.0%～121.0%之间,而汞和砷的回收率很低。在方法②处理样品所得溶液中,测得砷、铜、镉及汞的回收率达97.0%～127.0%之间,而铅的回收率较低,仅为51.8%。总之,方法①适合用于GF-AAS测定铅时的样品前处理,方法②宜用于HG-AFS测定汞和砷时的样品前处理,而方法③宜应用于GF-AAS测定铜及镉时的样品前处理。     

15种中成药中有害重金属铅、镉、铜含量的测定

为了解中药重金属污染情况,测定了市售常用15种中成药中重金属铅、镉、铜的含量,其中铅、镉采用石墨炉原子吸收法,铜采用火焰原子吸收法测定.结果表明,15种中成药均不同程度被这3种重金属污染,通心络中铅、镉、铜含量都已超标,桑菊感冒片镉超标,中药重金属污染问题仍然存在.     

青海种植山茛菪根部重金属元素特征

采集2～7年生人工种植山莨菪,用原子荧光光谱仪测定了镉、砷、汞,原子吸收光谱仪测定铅。结果表明,2—7年生种植山莨菪在每年9月份中,4种重金属元素含量水平由高到低依次为：砷、镉、铅、汞;铅和镉、砷和铅、且砷和镉之间均存在一定相关性。各种重金属的含量随着年份和生物量的增加而有所积累。     

原子吸收光谱法测定益寿回春口服液中砷铅镉铬汞的含量

采用原子吸收光谱法测定了益寿回春口服液中砷、铅、镉、铬和汞的含量，并参照食品中重金属的限量规定进行了比较。结果表明，益寿回春口服液中的砷、铅、镉、铬和汞均低于限量标准，为该产品的质量控制提供了依据。     

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。     

原子吸收光谱法及原子荧光光谱法测定中药丹参中五种金属元素

丹参样品用浓硝酸-过氧化氢(5+1)混合溶液消解后,在优化的仪器工作条件下,用火焰原子吸收光谱法测定所得样品溶液中铜的含量,用石墨炉原子吸收光谱法测定其中的铅和镉的含量,并用氢化物发生-原子荧光光谱法测定其中砷和汞的含量。5种元素的相对标准偏差(n=10)均小于3.0%。标准加入法测得5种元素的回收率在90.0%~110.0%之间。     

电感耦合等离子体质谱(ICP-MS)法检测市售鱿鱼中5种重金属

基于硝酸消解体系,建立了微波消解-电感耦合离子体质谱(ICP-MS)法同时测定市售鱿鱼中铅、砷、镉、汞、铬5种重金属元素的检测方法。样品加入HNO₃进行微波消解,优化ICP-MS 相关检测参数后,进行外标法定量。结果表明,5种重金属在各自浓度范围内线性关系均＞0.999,平均回收率为96%-101%,精密度RSD均小于5%。用该法检测广州市农贸市场随机购买的6个批次冰鲜鱿鱼,结果有1个批次砷含量超标,1个批次镉含量超标。该法前处理简单,检测准确、快速,适用于鱿鱼等水产品中铅、砷、镉、汞、铬等重金属的检测。     

原子吸收光谱法测定大承气颗粒剂中砷铅镉铬汞的含量

采用原子吸收光谱法测定了大承气颗粒剂及其原料药材中砷、铅、镉、铬和汞的含量，并参照食品中重金属的限量规定进行了比较。结果表明，大承气颗粒剂及其原料药材中的砷、铅、镉、铬和汞均低于限量标准，成品中重金属的含量均低于原料药材中的平均含量，这为大承气颗粒剂生产中的质量控制提供了依据。     

电感耦合等离子体质谱法测定虎杖中铜砷镉汞铅

采用微波消解法处理中药材虎杖样品,用电感耦合等离子体质谱法测定样品中铜、砷、镉、汞、铅5种元素的含量。优化了仪器工作参数,选择锂(6Li)、钪(45Sc)、锗(72Ge)、铟(115In)、铋(209Bi)作为内标物质。5种元素均在一定的质量浓度范围内呈线性,检出限(3S/N)在0.013~0.120μg.L-1之间。铜、铅、镉、汞、砷的回收率分别为103.4%,100.2%,104.6%,89.7%,92.9%;相对标准偏差(n=5)分别为1.14%,0.55%,1.82%,1.91%,1.40%。     

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%.     

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%).     

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.     

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.     

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.