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程键 《中国无机分析化学》2014,4(2):5-7
采用B-HNO3-A溶解样品,硝酸钯作基体改进剂,通过优化仪器分析条件,灰化温度为500℃,原子化温度为1 800℃,成功实现了石墨炉原子吸收光谱法测定湿法冶炼锌基体物料锌精矿、锌焙砂、氧化锌、锌粉等物料中微量铊。方法对照实验结果与电感耦合等离子体质谱法(ICP-MS)测定值基本一致。方法的相对标准偏差(RSD,n≤8)为1.7%~7.8%,加标回收率为99%~103%。 相似文献
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建立石墨炉原子吸收光谱法直接测定铁镍基高温合金中的锡元素。通过研究基体效应、溶样酸、基体改进剂、灰化温度、原子化温度以及不同激发光源类型,确定最佳测定方案:用2 m L盐酸和0.4 m L硝酸溶解合金样品,灰化温度为1 200℃,原子化温度为2 200℃,选用0.003 mg Pd(NO_3)_2和0.03 mg NH_4H_2PO_4作为基体改进剂。在空心阴极灯(HCL)和无极放电灯(EDL)两光源条件下,标准工作曲线的线性相关系数均大于0.999,分别对GBW 01632和GBW 01634的测定结果与认可值进行t检验(α=0.05),均无显著性差异,短期稳定性好(RSD5.0%,n=8),锡的检出限分别为0.82μg/L(HCL)和0.75μg/L(EDL)。该方法无需萃取或其它复杂的前处理过程,测定结果准确、可靠,可实现铁镍基合金样品中锡的直接测定。 相似文献
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1 引言 测定稀土氧化物中微量铝,多采用分光光度法、X-射线荧光光谱法、发射光谱法等。石墨炉原子吸收光谱法具有灵敏度高、选择性好等优点,可应用于高纯稀土氧化物中痕量铝的测定。 2 实验部分 2.1 仪器及主要操作条件 美国P-E2380型原子吸收光谱仪;HGA-400型石墨炉;56型记录仪;热解石墨管;铝空心阴极灯。灯电流20mA,氘灯背景校正器,测定波长为309.3nm;狭缝宽度0.7nm;载气为氩气,原子化时采用最大功率加热和停止内部气体流量。石墨炉操作条件为灰化温度1500℃,原子化温度2600℃。 2.2 主要试剂 铝的标准溶液用0.1g金属铝(99.99%)溶于硝酸配制成1mg/ml铝;PH5.5的缓冲溶液:1 相似文献
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目的探索石墨炉原子吸收法直接测定海水中铅的检测方法。方法用硝酸铵稀释海水样品,用硝酸钯和磷酸二氢铵作为基体改进剂,用石墨炉原子吸收法测定了海水中的铅含量。结果通过加标回收的验证,检测结果准确可靠。结论适合用于海水中铅含量的测定。 相似文献
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石墨炉原子吸收光谱中海水的背景吸收研究 总被引:2,自引:0,他引:2
莫胜钧 《高等学校化学学报》1988,9(11):1176
由于海水的成分复杂,含盐量高,给用石墨炉直接测定其中的痕量杂质带来许多困难[1]。Sturgeon等用预先分离的方法来克服干扰[2]。为了进行直接测定,研究海水背景吸收的来源、特点和消除方法是重要的。海水背景吸收的波长特性和在石墨管内蒸发行为的研究表明,海水的背景吸收主要来自氯化钠。时间特性的研究表明,背景吸收的时间分布及背景峰高与原子化阶段的加热方式和原子化温度有关。作者还研究了基体改进。剂和其它减小背景吸收的方法。 相似文献
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硫磺样品在微波消解仪中经硝酸消解,用石墨炉原子吸收光谱法测定其中的铁含量。以1g·L-1硝酸镁溶液(10μL)作为基体改进剂,灰化温度为1 200℃,原子化温度为2 000℃。铁的质量浓度在3.0~25.0μg·L-1范围内与其吸光度呈线性关系,方法的检出限(3s/k)为0.5μg·L-1。对工业硫磺样品进行测定,测定值的相对标准偏差(n=6)为2.2%。用标准加入法进行回收试验,计算得回收率在99.5%~101%之间。 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
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. 相似文献
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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. 相似文献
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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%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献