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.     

高效液相色谱-电感耦合等离子体质谱测定蟾酥中铜、砷、镉、汞、铅含量及砷化学形态

建立了微波消解-电感耦合等离子体质谱(ICP-MS)测定蟾酥中Cu、As、Cd、Hg、Pb等元素含量的分析方法,检出限为0.28～5.7 μg/L,元素加标回收率均在91.5%～115%.用1.2 mol/L HCl浸提蟾酥中的As形态,利用高效液相色谱(HPLC)与电感耦合等离子体质谱(ICP-MS)联用技术对蟾酥样品中的As化学形态进行了初步探讨,发现其中As主要以有毒的无机As(Ⅴ)形态存在,并讨论了形态分析的方法及结果.本方法适用于蟾酥中药样品质量控制和安全评估的要求.     

微波消解-原子荧光光谱法测定中草药中砷和汞

采用微波消解处理样品,利用双通道原子荧光光谱法测定中药材杜仲中As和Hg的含量。最佳实验条件下,As、Hg的检出限分别为0.235、0.0773ng/mL,回收率在90.74%～94.30%、90.57%～101.50%之间。方法快速、简便、准确且灵敏度高,为中药材中重金属含量测定提供了较好的方法。     

氧化-吹扫-金柱捕集-(双柱)热脱附-电感耦合等离子体质谱测定液体和固态样品中痕量汞同位素含量

建立了液体和固态环境样品中痕量Hg同位素的氧化-吹扫-金柱捕集-热脱附-电感耦合等离子体质谱(ICP-MS)测定法。样品采用美国环保局(USEPA)1631方法预处理,气液分离降低基底干扰,金柱富集提高灵敏度;将Hg蒸气直接引入ICP-MS,利用ICP-MS的分辨能力,测定Hg同位素。198 Hg和201 Hg的检测限分别为0.07、0.11ng/L;土壤、沉积物和生物等固体样品中198 Hg和201 Hg的检测限分别为0.15、0.20ng/g。在最佳条件下,连续7次测定198 Hg和201 Hg基底加标水样,测定结果的相对标准偏差(RSD)均为7.0%,同位素比值(201 Hg/198 Hg)的内精度为0.26%(I RSD)。痕量198 Hg和201 Hg海水样基底加标回收率分别为98.3%～116.0%、92.4%～109.4%,生物样198 Hg和201 Hg的基底加标回收率分别为88.4%～106.7%、79.7%～88.0%。与标准参考溶液198 Hg和201 Hg的相对偏差分别为-0.15%、-0.09%。对于褶牡蛎的同位素组成分析,2次测定同位素比值(201 Hg/198 Hg)与自然界Hg同位素比理论值的相对偏差分别为0.4‰、-6.0‰。该方法成功用于标准参考样品和实际生物样品的同位素组成分析,并可成为Hg迁移和转化示踪实验的分析技术手段。     

ICP-MS法测定亚热带水果中的重金属含量

用电感耦合等离子体质谱(ICP–MS)法测定亚热带水果中Pb,Cd,As,Hg元素的含量,对实验条件进行优化,样品用微波消解法进行预处理,用Bi,In,Ge作内标校正基体干扰和漂移。Pb,Cd,As的线性范围为0.0～20.0ng/mL,Hg的线性范围为0.0～2.0 ng/mL,线性相关系数均为0.999 9。Pb,Cd,As,Hg元素的检出限分别为0.027,0.008,0.011,0.051 ng/mL,测定结果的相对标准偏差(n=6)在3.63%～5.72﹪之间,加标回收率为90.2%～102.0%。用该法测定茶叶、大米和小麦3种国家标准物质,测定结果均在标称值范围内。     

浸提法-ICP-AES测定化妆品中有害元素铅、砷、汞

建立了浸提法-电感耦合等离子体发射光谱(ICP-AES)测定化妆品中Pb、As、Hg的方法,并对ICP-AES工作参数及条件进行了优化和选择.Pb、As、Hg检出限分别为0.0078,0.011和0.023 μg/mL.线性范围为0～500 μg/L,相对标准偏差为1.3%～3.9%;回收率为90%～101%.适用于化妆品中Pb、As、Hg的日常检测.     

常压湿式消解/常压微波消解-原子光谱法测定近海海洋生物体中Cu、Pb、Cd与Hg、As

采用常压湿式消解、常压微波消解两种方法处理近海海洋生物体,以石墨炉原子吸收法测定Cu、Pb、Cd和氢化物发生原子荧光法同时测定Hg、As。实验表明,以常压湿式消解法处理生物体,其Cu、Pb、Cd回收率分别为92%、103%、105%,而Hg、As的回收率分别是52%、58%。以常压微波消解法处理生物体,其Cu、Cd、Hg、As回收率分别为86%、94%、112%、94%,但用于Pb的测定,其回收率严重偏低。常压湿式消解、常压微波消解分别被用于海洋生物体样品中Cu、Pb、Cd和Hg、As的测定,有较好的测定结果。     

微波消解-电感耦合等离子体质谱法测定人面果树中的重金属元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定人面果树中As,Cr,Cd,Pb,Ni,Se,Hg 7种重金属元素含量的方法。样品采用HNO3-H2O2消解体系,避免了赶酸的操作,经微波消解后,用电感耦合等离子体质谱(ICP-MS)测定样品中As,Cr,Cd,Pb,Ni,Se,Hg 7种重金属元素的含量。方法对7种元素的校准曲线的相关系数r>0.9997,检出限在0.0098～0.0874μg/L之间,回收率在93%～115%之间,RSD在0.41%～4.9%。     

氢化物发生-原子荧光光谱法测定1：5万区域地质调查样品中的As、Sb、Bi、Hg等4种元素

建立了氢化物发生-原子荧光光谱法测定1∶5万区域地质调查样品中的As、Sb、Bi、Hg等4种元素的分析方法,通过采用王水(1+1)分解样品,在盐酸(5%)介质中用硼氢化钾作为还原剂对As、Sb、Bi、Hg等4种元素进行氢化物发生-原子荧光光谱法测定。方法检出限为0.008 9(As)、0.008 1(Sb)、0.008 1(Bi)、0.001 7(Hg)μg/g,测定结果的相对标准偏差(RSD,n=12)为0.82%～7.6%,准确度△lgC=-0.01～0.02。方法简便、成本低,检测结果准确,检出限、准确度及精密度均能达到行业规范要求,适用于1∶5万区域地质调查样品水系沉积物、土壤中As、Sb、Bi、Hg等4种元素的测定。     

电感耦合等离子质谱法测定化妆品中的有害元素

用电感耦合等离子质谱法测定了抽检化妆品中有害元素Pb、As、Hg.采用内标元素Sc校正As,内标元素Eu校正Pb和Hg,获得满意的测定结果.方法检出限为0.03～0.05 ng/mL,变异系数（CV%）为0.3%～5.0%,加标回收回收率为95%～105%.     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.