微波消解样品-冷原子吸收光谱法测定鱼粉中微量汞

以微波溶样技术消解样品,采用正交试验设计优化冷原子吸收光谱法测定汞的试验条件,并对微波消解条件和共存离子的干扰进行了试验。试验表明：汞含量在30μg·L^-1范围内服从比耳定律,方法的检出限为0．13μg·L^-1,相对标准偏差为2．6％,回收率为97．6％～106．8％。     

流动注射-化学发光法测定片剂中左炔诺孕酮含量

在酸性条件下,高锰酸钾与亚硫酸钠能够产生较弱的化学发光,而左炔诺孕酮能够增强该化学发光强度。在一定浓度范围内,增加的发光强度与左炔诺孕酮的浓度呈线性关系,由此建立了一种测定左炔诺孕酮的流动注射化学发光方法。方法的检出限（S／N=3）为6．4μg·L^-1,线性范围为0．01～0．5mg·L^1-和0．5～5．0mg·L^-1,对0．1mg·L^-1左炔诺孕酮平行测定11次,其相对标准偏差为4.3％。     

应用液-液色谱联用技术在线富集测定环境水中西维因和抗蚜威的残留量

为高效液相色谱法测定环境水样中残留的西维因和抗蚜威的含量,应用了液-液色谱联用技术,实现了在线富集、分离和检测。分析中用YWG-C18（10mm×4．6mm,10μm）和YWG-C18（150mm×4．6mm,10μm）依次作为富集柱和分离柱,以体积比45比55混合的甲醇与水的混合溶液作为流动相,其流速为1．0mL·min^-1。选定紫外光度检测的波长为228nm,试样溶液在富集柱上的流速为5．0mL·min^-1。此外,对渗漏体积等参素也作了试验,分析信号值与两农药的质量浓度在0．04～1．0μg·L^-1范围内呈线性关系。测得方法的检出限（S／N=3）为0．008μg·L^-1（西维因）和0．014μg·L^-1（抗蚜威）,回收试验的结果在93％～119％之间。还对日内和日间精密度进行了试验,测定西维因的日内精密度为1．3％～20．0％,日间精密度为2．39／6～22．2％,测定抗蚜威的日内精密度为2．0％～10．8％,日间精密度为2．2％～5．8％。     

固相微萃取-气相色谱法测定橙汁中残留有机氯杀虫剂

自制碳纳米管涂层萃取探头,顶空目相微萃取-气相色谱法测定橙汁中有机氯杀虫剂六六六和滴滴涕,优化了影响萃取效率的因素：萃取时间和温度、离子强度、有机溶剂、顶空体积、pH和样品的稀释度等。在0．05～6．0μg·L^-1范围内呈线性关系,方法的检出限在0．003～0．022μg·L^-1之间。该方法用于橙汁样品的测定,对不同的杀虫剂,加标回收率为71．0％～131．0％,相对标准偏差小于10％。     

微波消解样品-石墨炉原子吸收光谱法测定豆制品中铅

豆制品试样置于微波消解罐中用硝酸及过氧化氢在MDS-2002A型微波消解仪中消解,所得试样的稀硝酸溶液,在加入硝酸铵后直接进样作石墨炉原子吸收光谱法测定。硝酸铵的加入除作为基体改进剂外,还能起提高灰化温度和消除氯化钠干扰的作用。对仪器的工作条件,特别是石墨炉工作程序的参数,包括烘干时间、灰化及原子化温度等进行了试验并予以优化。所选用的分析谱线的波长为283．3nm,在所测得的峰高积分值与铅的质量浓度在2～80μg·L^-1范围内呈线性关系。方法的检出限（S／N=3）为0．1μg·L^-1。以豆制品样品为基体加入铅标准溶液做方法的回收试验,测得回收率在94．0％～102．0％之间。     

微柱富集-石墨炉原子吸收光谱法测定痕量钼

提出和制备了一种负载苯基荧光酮（PF）的滤纸纤维柱,用于石墨炉原子吸收光谱法测定痕量钼的预富集。试验表明：在pH2．0时,控制待测液流速在2．0mL·min^-1以内,可定量富集钼（Ⅵ）,饱和吸附量为25．2μg·g^-1。用流速1．0mL·min^-1的氨水（3＋97）2．0mL,可将5．0μg钼（Ⅵ）从吸附柱上定量洗脱。对国家地质标准物质GSS5和GSR1的分析结果表明,该方法可靠。测定了人工合成锌样、铜精矿中痕量钼,方法的检出限为1．01μg·L^-1,回收率为92．0％～103．0％。     

吹扫-捕集/气相色谱-质谱联用法测定城市饮用水中挥发性卤代烃

采用吹扫-捕集器富集了城市饮用水样中11种挥发性卤代烃,经气相色谱法分离后用质谱法选择性离子监测模式进行定量测定,所测定的卤代烃,除含量相对较高的三氯甲烷外,线性范围在0．04～11．0μg·L^-1之间;检出限（S／N=3）均小于6pg·L^-1。对方法的回收率及精密度作了试验,测得回收率在85．6％～126．1％之间,相对标准偏差（n=7）在2．06％～3．87％之间。     

大口径石英毛细管柱气相色谱法测定黄豆甙原中有机溶剂残留量

用毛细管气相色谱法测定黄豆甙原中有机溶剂残留量。试样0．5g溶于含有内标正丁醇的二甲亚砜中,定容5mL。在优化条件下,用配有DB-17石英毛细管分离柱（0．54mm×30m,1．0μm）和火焰电离检测器的毛细管柱气相色谱仪测定黄豆甙原中残留的有机溶剂乙醇和N,N-二甲基甲酰胺（DMF）。乙醇和DMF的检出限分别是9．6pg和5．7ng;回归方程和相关系数分别为Y=0．04627＋0．65369X,r=0．9982和Y=0．02531＋0．35654X,r=0．9934;线性范围分别为50．4～718.9g·L^-1和9．8～137．2g·L^-1。     

电感耦合等离子体原子发射光谱法测定高纯铌中微量钽

应用电感耦合等离子体原子发射光谱法,采用标准加入法对高纯铌中微量钽进行测定。当铌的质量浓度为10g·L^-1时,钽的测定范围为50-500μg·g^-1,回收率为101％～103％,相对标准偏差（n=6）为4.0％～7.3％。     

离子色谱法测定环丁砜中痕量阴离子

采用离子交换树脂处理除去样品中杂质干扰组分,很好地消除了基体效应。以Dionex AS9-HC作为分离柱,AG9-HC作为保护柱,9mmol·L^-1碳酸钠溶液作为淋洗液,抑制电导检测。离子色谱法测定环丁砜中氯离子、硝酸根、硫酸根阴离子,检出限分别为14,39,54μg·L^-1,方法的回收率在104.2％～123．2％之间。     

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%.     

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.     

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.     

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.