电感耦合等离子体原子发射光谱法(ICP-OES)测定水系沉积物中6种重金属元素

建立了自动消解仪消解-电感耦合等离子体原子发射光谱法(ICP-OES)同时测定水系沉积物中Cu,Zn,Ni,Cr,Pb,Co 6种元素含量的方法。方法中6种元素的检出限为0.000 2~0.02mg/L,工作曲线的相关系数均大于0.999。方法经国家标准物质(GBW07361)验证,准确度和精密度均能达到环境监测分析的要求,为水系沉积物中重金属元素含量的测定提供了简单可靠的分析方法。     

聚氨酯泡沫富集-电感耦合等离子体原子发射光谱法(ICP-AES)测定土壤及水系沉积物中铊含量

建立了一种以聚氨酯泡沫富集-电感耦合等离子体原子发射光谱法(ICP-AES)测定土壤及水系沉积物中铊含量的分析方法,利用正交实验,确定最佳实验条件,方法的检出限为0.01mg/L,对土壤及水系沉积物标准物质的测定结果与推荐值相符,相对误差小于10%,相对标准偏差(RSD,n=10)在1.9%~4.9%。     

微波消解-氢化物发生-冷原子荧光光谱法快速测定水系沉积物中的总汞

建立了快速测定水系沉积物中总汞的方法。采用单因素试验探讨了仪器条件、HCl浓度以及KBH4浓度对汞荧光强度的影响。在最佳试验条件下,汞的线性回归方程为IF=516.362c+11.982,相关系数为0.9998,线性范围为0.004~1.6 ng/m L,方法检出限为0.004 ng/m L。对水系沉积物标准物质(GBW07305)进行分析,其测定值(0.10±0.01μg/g)与标准值(0.10±0.02μg/g)完全吻合,相对标准偏差为5%(n=11),回收率在100%~110%之间。方法已用于水系沉积物总汞含量的测定。     

微波消解试样-电感耦合等离子体质谱测定水系沉积物中钨和钼

用电感耦合等离子体质谱法测定水系沉积物试样中钨和钼的量,试样用硝酸和氢氟酸在MARS 5型微波消解仪中作消解处理。对仪器的工作参数做了试验并予以优化,测得方法对钨及钼两元素的检出限(3s/k)依次为0.03,0.07μg.g-1。通过分析4个水系沉积物标准物质对所提出方法的准确度和精密度作了考核,所测得钨和钼的结果均与4个标准物质的认定值相一致,各测定值的相对标准偏差(n=7)均小于8.5%。     

盐酸-氯化亚锡-氟化铵体系溶样-火焰原子吸收光谱法测定水系沉积物中的低含量黄铁矿

建立了HCl-Sn Cl2-NH4F体系溶样,火焰原子吸收光谱法测定水系沉积物中低含量黄铁矿的分析方法,在过量Sn Cl2存在下,在HCl介质中,用NH4F能选择性地保留黄铁矿,继而使用稀HNO3溶解黄铁矿。方法检出限为0.014μg/m L,RSD(n=12)为2.1%~3.7%,加标回收率为96.0%~105.5%。方法适用于水系沉积物中低含量黄铁矿的测定。     

氢化物发生-原子荧光光谱法测定水系沉积物中铋和汞

水系沉积物试样用盐酸-硝酸-水(3+1+4)混合溶液溶解,氢化物发生-原子荧光光谱法测定铋和汞的含量。对介质酸度、硼氢化钾浓度、负高压和灯电流等影响铋和汞测定因素进行了试验并予以优化。铋和汞的检出限(3S/N)分别为0.02,0.01μg.L-1,相对标准偏差(n=11)均小于0.5%。应用此法分析了水系沉积物标准样品,测定值与推荐值相符。     

王水提取-电感耦合等离子体质谱法同时测定地质样品中微量银、镉、铋

样品用水浴加热、王水提取预处理,采用电感耦合等离子体质谱法同时测定了土壤、水系沉积物及岩石等地质样品中的痕量Ag、Cd和Bi。在样品预处理阶段,主要干扰元素Zr和Nb只有少量被溶出,而分析元素Ag、Cd和Bi的溶出趋于完全,这样在样品预处理阶段就完成了分析元素与干扰元素的有效分离,减小了多原子离子93Nb16O ,92Zr16OH ,92Mo16OH 对109Ag的干扰和95Mo16O ,94Zr16OH ,94Mo16OH 对111Cd的干扰。方法对实际样品的检出限(10σ,DF=300)Ag,Cd和Bi的质量分数分别为5.1,4.3和10.5ng/g。对不同含量样品7次测定的RSD为8.7%~1.8%。用该方法对土壤、水系沉积物及岩石等国家一级标准物质进行分析,分析数据均在标准推荐值的允许误差范围内。     

激光剥蚀电感耦合等离子体质谱快速分析水系沉积物主量及痕量元素

基于193 nm ArF准分子激光器与四级杆电感耦合等离子体质谱联用,我们描述了固体样品分析中定量校准的基本原理,提出了一个简单,快速、同时分析水系沉积物中主量及痕量元素的方法:无内标校准法.分析了水系沉积物中主、痕量共52种元素.对水系沉积物标准参考物质GSD-4的分析,结果与推荐值具有良好的一致性,相对误差<15%的有46个元素,<10%的有36个元素;大多数元素的相对标准偏差<10%.结果表明,运用多个外标和无内标校准法,能够对水系沉积物样品进行多元素快速、同时分析,分析结果的准确度优于传统的外标-内标结合校准法.     

X射线荧光光谱法测定农田底泥中8种元素

建立X射线荧光光谱法测定农田底泥样品中砷、铬、铜、锰、镍、铅、锌、铁8种元素含量的分析方法.以塑料环粉末压片法制样,选用50种土壤、水系沉积物标准物质拟合校准曲线,探讨各元素的测定条件.当待测样品与建立校准曲线的标准样品粒径均小于75μm时,能够有效减少矿物效应和粒度效应的影响,从而提高检测准确度;各元素在各自的含量范...     

Epsilon5高能偏振能量色散X-射线荧光光谱仪测定垃圾焚烧灰渣中有害元素

使用粉末样品压片制样,用Epsilon5高能偏振能量色散X射线荧光(EDXRF)光谱仪测定垃圾焚烧灰渣中S、Cl、Ba、Cr、Cu、Na、Mn、Pb、Zn、Cd、As、Mo等多种有害元素,采用土壤、水系沉积物、海底沉积物、矿物等国家标准物质和人工合成标样作为校准。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.