微波消解ICP-MS测定海洋沉积物中微量元素

采用微波消解-电感耦合等离子体质谱(ICP-MS)法同时测定海洋沉积物中的Cr、Co、Ni、Cu、Zn、Cd、Pb7种微量元素。对微波消解酸体系和微波程序进行了优化,结果表明:由4 mL HNO3与2 mL HF组成的混合酸对沉积物消解效果好;阶段升温,最高温度200℃,消解30 min有着最佳的消解效果。采用本实验方法对7种不同类型的海洋沉积物标准物质进行了测定,测定结果与标准值一致。各元素的检出限在0.009~0.17 ng/g之间。该方法快速简便、准确度高,可用于海洋沉积物样品中多元素同时测定。     

ICP-AES连测饲料中的Ca、P、Cr、Cd、Pb、As

应用ICP-AES对饲料中的Ca、P、Cr、Cd、Pb、As的测定进行了研究,确定了合理的测试条件,对微波消解和干法消解样品进行了比较,采用标准物质测定与样品加标回收进行了方法验证。结果表明,微波消解回收率达96%~104%,变异系数小于5%,结果令人满意。该法可同时检测饲料中的多种元素,且精密度高,进样量少,节省试剂,方便快捷。     

三种消解方法在测定近海沉积物中Pb、 Cu、 Cd、 Hg及As的应用

常压湿式消解、高压微波消解、常压微波消解3种方法被应用于近海沉积物中Pb、 Cu、 Cd、 Hg、 As 5种重金属元素的分析. 以近海海洋沉积物标准物质为样品经3种方法消解后, 通过石墨炉原子吸收法测定Pb、 Cu、 Cd和氢化物发生原子荧光法同时测定Hg、 As. 结果表明, 样品经常压湿式消解, 其Pb、 Cu、 Cd回收率在80%～123%内而Hg、 As回收率低;经高压微波消解, 标样中Pb、 Cu、 Cd、 As回收率在84%～117%内, 对Hg测定回收率偏低;常压微波消解更适合于Cu、 Cd、 Hg、 As的消解, 其回收率在95%～121%之间而Pb回收率低于42.4%. 常压湿式消解与常压微波消解被用于大亚湾人工渔礁区沉积物样品的处理, 有较好的测定结果.     

电感耦合等离子体串联质谱法测定活性白土中痕量毒理性元素

建立了不同样品消解方式下,检测活性白土中痕量毒理性元素的电感耦合等离子体串联质谱(ICP-MS/MS)分析方法。分别采用微波和密闭压力对活性白土样品进行消解,利用ICP-MS/MS法测定其中Cr、Ni、As、Cd、Sn、Sb、Hg和Pb共8种毒理性元素。在MS/MS模式下,分别以O_2和NH_3/He为反应气消除了测定过程中的质谱干扰。各元素具有良好的线性关系(R2≥0.9999),检出限为0.35~5.20 ng/g。应用与活性白土基质组成相似的国家标准参考物质水系沉积物(GBW07306)验证了分析方法的准确性和精密度,结果显示,采用微波消解和密闭压力消解对样品进行前处理的测定值与标准参考物质的证实值基本一致,相对标准偏差(RSD)≤5.2%,验证了分析结果准确可靠、精密度高。本方法具有分析速度快、检出限低且无干扰的优点,适用于活性白土中痕量毒理性元素的高通量分析。     

电感耦合等离子体质谱同位素稀释法测定菜园土壤中微量镉

用电感耦合等离子体质谱同位素稀释法,测定了菜园土壤中微量镉的含量。土壤样品中加入一定量的112Cd富集同位素试剂后,用硝酸-氢氟酸-高氯酸混合酸预消解后再经微波消解,冷却后样品溶液在130℃蒸发近干,然后加入硼酸1 mL,以硝酸(2+98)溶液定容至20 mL,利用电感耦合等离子体质谱法测定溶液中的同位素比值R(112Cd/111Cd),用同位素稀释法计算出样品中镉的含量。试验对仪器参数1、12Cd富集同位素试剂的加入量、质量歧视因素、仪器死时间及同量异位素和多原子离子峰的干扰等因素对测定产生的影响进行了试验和校正。在优化的条件下测定了土壤标准物质(GBW 07423)中镉的含量,测定值与标准值相符。     

电感耦合等离子体原子发射光谱法测定黄连中铁、镁、锌含量

<正>样品基体对元素测定的准确性产生重要影响,特别是中药样品。目前,中药中很多成分还未被研究,因其基体成分非常复杂,需进行样品前处理。消化处理是元素分析中一种常用的样品前处理方法,即消解样品中的有机物。由于有些待测元素以化合物的形式存在于中药材中,需要破坏有机物的价键结构,从而释放出被结合的待测元素。已见报道的消化处理方法主要有湿法消化[1]、微波消化[2-3]、干法灰化[4]和密闭压力罐法[5],其中干法灰化、湿法消     

虾粉中总砷测定方法的探讨

用氢化物原子荧光光度法测定虾粉中总砷含量时,对干法灰化、湿法消解、微波消解3种样品处理方法对虾粉中砷元素测定结果的影响进行了比较。通过试验确定了最佳消解条件。砷元素浓度在0~10μg/L的范围内与荧光强度呈线性关系,线性相关系数r=0.999 6,检出限为0.2μg/L。比对结果表明,干法灰化适合于测定虾粉中总砷的含量,湿法消解测定总砷的含量偏低,微波消解不适合测定虾粉中总砷的含量。采用干法灰化-氢化物原子荧光光度法测定虾粉中总砷含量,加标回收率为76.2%~106.0%。     

多接收等离子质谱高精度测定现代人齿中Mg同位素

Mg是构成牙齿重要组分,其含量和同位素组成可记录居民生活地域、饮食习惯以及口腔健康信息等重要信息.本研究建立了高精度多接收等离子质谱(MC-ICP-MS)测定牙齿中Mg同位素方法.牙齿样品经微波消解仪消解,后采用AG50W-X8阳离子树脂分离溶液中的Mg元素,以1 mol/L HNO3为介质上柱,40 mL1 mol/L HNO3洗脱Na+等杂质离子,再以30 mL 1 mol/L HNO3收集Mg元素,60 mL 1 mol/L HNO3洗去其它杂质,蒸干Mg收集液.MC-ICP-MS进行Mg同位素组成测定.MC-ICP-MS仪器自身的质量分馏利用“样品-标准”交叉技术(“Sample-standard”bracketing technique)解决.实验结果表明,利用AG50W-X8阳离子树脂,可在保证Mg回收率的情况下,将牙齿样品中的Mg和其它基质元素彻底分离,且不造成同位素分馏.采用此方法对现代人离体牙牙釉质中Mg同位素进行分离测定,牙齿的δ25Mg在较大的范围变化(-1.38‰ ～4.59‰).本方法为利用人牙齿中Mg同位素研究Mg的暴露水平、环境污染等信息提供重要的实验和理论依据.     

电感耦合等离子体质谱同位素稀释法测定沉积物和茶叶标准物质中铅的研究

采用2种微波消解体系(HNO3-H2O2和HNO3-H2O2-HF)及3种定量模式(同位素稀释法、标准工作曲线法和标准加入法),对沉积物和茶叶标准物质中的铅进行测定,结果表明:同位素稀释质谱法的各项检测指标显著优于其它两种定量模式(茶叶中铅含量测定值为4.30 μg/g),标准加入法次之(3.75 μg/g),标准工作曲线法较差(3.61 μg/g).二种微波消解体系中,加HF酸优于不加HF酸,不加HF,茶叶中铅的回收率仅有89%,加入HF则上升为98%.     

密封石英管爆裂法快速分析包裹体中CO2碳同位素

传统的包裹体中CO2碳同位素制备分析方法,通常是在真空条件的管式加热炉中对样品进行加热爆裂,进而释放包裹体中的CO2,并对其进行提取纯化,测定碳的同位素组成。本实验建立了密封石英管爆裂法:将包裹体样品在真空条件下密封在单个的石英样品管中进行加热爆裂,进而收集纯化CO2气体,再对其进行碳同位素分析测试。密封石英管爆裂法能够获得高精度的碳同位素分析数据(1s=0.04‰)。对于包裹体样品(IGGZhu)的CO2碳同位素分析结果虽然具有较大的分布范围(!3.6‰~!6‰),但其反映的是多期次包裹体混合的结果。另外,由于包裹体样品可以集中批次统一爆裂,简化了操作流程,提高了实验测试效率。单个石英样品管也避免了样品之间的污染问题。     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.