石墨炉AAS法测定间隙水、上覆水中痕量铅、镉、铜

本文参考石墨炉原子吸收测定铅、镉、铜的有关报导,采用APDC—DDTC/MIBK在小试管中同时萃取,富集、分离海洋沉积物间隙水、上覆水中待测元素,再用石墨炉平台原子吸收法直接测定有机相中的铅、镉、铜。铅、镉的测定灵敏度分别提高到管壁进样时的2.8和1.7倍,并消除了干     

石墨炉原子吸收法连续测定气溶胶中重金属

提出了用石墨炉原子吸收法连续测定气溶胶中六种重金属的方法.气溶胶样品经处理后,直接用石墨炉原子吸收法测定其中的铜、钴、镍、镐、铅和铬.其检出限在 1.9×10~(-12)～1.6×10~(-10)g,仪器的精密度(RSD)<6.1%,标准加入回收率为90.4%～106.5%,已用于大批气溶胶样品的测定,结果令人满意.     

石墨炉原子吸收法测定岩石中锡

石墨炉原子吸收法测定锡多用于金属试样分析。池田等曾以镧作共沉淀剂,在氨性介质中使锡共沉淀,然后于1N硝酸中,利用镧的增感效应,以石墨炉原子吸收法测定了金属锌和铜中锡。本文拟定了石墨炉原子吸收测定岩石中锡的方法,以钼酸铵作添加剂,不仅可以增强待测元素锡的吸收信号,还可以抑制某些共存元素的干扰,可不经分离直接测定岩石试样中0.2～0.00005%的锡。方法简便,精密度和准确度均令人满意。本方法也可应用于生物组织及其它试样中锡的测定。     

石墨炉原子吸收法测定高纯硒中痕量铁

研究了石墨炉原子吸收直接进样法和石墨炉内富集法测定高纯硒中痕量铁的条件,建立了石墨炉原子吸收法直接测定高纯硒中痕量铁的分析方法.直接进样法的检出限为0.008 μg/g,石墨炉内富集法的检出限为0.004 μg/g,相对标准偏差分别为:5.2%和4.6%,两种方法检测样品结果基本一致.测定含铁0.3 μg/g的高纯硒,测定值的RSD为4.6～5.2%.     

若干建筑涂料原料中铅含量的测定

装修涂料中的铅元素是室内环境污染的重要因素之一。石墨炉原子吸收法主要用于测定痕量金属元素,在性能上比其他方法好,并且适用于少量样品的分析和固体样品直接分析,采用该法测定了5种常用建筑涂料原料中铅元素的含量,标准曲线线性范围在0~50μg/L,相关系数r=0.999 059,测试结果显示,5种涂料的吸光度为0.017~0.067,铅质量分数均低于90 mg/kg,符合国家建筑材料环保要求。     

石墨炉原子吸收光谱法测定新疆出口番茄酱中的铅和镉

报道了微波消解石墨炉原子吸收光谱法测定番茄酱中的铅、镉。研究了石墨炉原子吸收测定的最佳条件。该方法测定铅和镉的线性范围分别为0.00~25 ng/mL、0.00~8 ng/mL;相对标准偏差分别为2.15%、3.10%;回收率分别为98.6%、104.5%。利用国家标准物质番茄叶(ESP-1)验证了方法的准确度,测定值与标准值基本吻合。研究表明,该方法具有很好的准确度和精密度。     

应用平台石墨炉测定矿山污水中微量铜

近几年来,国内已有人对石墨炉平台技术进行评价并在实际分析中利用这一技术,如应用石墨炉平台技术测定金属铅中微量铊。有关平台技术国外有不少报导。如Kaiser等人研究了在石墨炉中加上L'vov平台和基体缓冲剂分析自来水和合成水中的铅、镉等元素,认为可以大大减少基体的干扰。本文应用170-70型塞曼效应原子吸收分光光度计,在石墨炉中加上热解平台,对测定矿山污水中微量铜进行了探讨性的研究。实验表明,应用热解平台石墨炉可以消除或减少酸及基体的干扰。本法的检出限为3ppb,测定浓度范围0—0.1微克/毫升。     

石墨炉原子吸收法直接测定高纯铜中痕量杂质砷硒锡

Bedard曾用氢化物火焰原子吸收法测定电解铜中砷、硒、碲、锡;Mullen用石墨炉原子吸收法测定高纯铜中硒、碲、铋、锑及砷,结果基体铜对测定均有干扰,因此,分别用氢氧化镧、氢氧化铁共沉淀欲测元素,与铜分离后再进行测定。Haynes测定高纯铜中砷、锑、硒、碲;Barnett测定铁合     

平台石墨炉原子吸收法直接测定镍基合金中铅和锑

平台石墨炉原子吸收法直接测定镍基合金中铅和锑谢文兵，姚金玉，胡庆兰（中国科学院长春应用化学研究所长春１３００２２）关键词石墨炉原子吸收，镍合金，铅，锑，基体改进剂石墨炉原子吸收法是测定痕量元素最有效的方法之一。但是铅和锑都是易挥发元素，为了增强灰化过...     

石墨炉-原子吸收法测定矿石中的镱

用石墨炉-原子吸收法测定镱时,原子化温度选在2700℃以上为宜,绝大部分共存元素无干扰,镱量在0.02ppm时,变动系数为3.6％,灵敏度为1.2—2.4×10~(-11)克/1％,本方法适用于矿石中镱的测定。试验部分 (一)仪器 Perkin-Elmer400型原子吸收分光光度计。 HGA-74型石墨炉。 HGA-2100型石墨炉电源/控制器。 56型记录器。 (二)条件试验 1.氩气流量:在原子化不停气的情     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

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.     

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.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.