单颗粒-电感耦合等离子体质谱法表征纳米抗菌商品中纳米银颗粒粒径分布

建立了单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定纳米抗菌商品中纳米银颗粒(Silver nanoparticles,AgNPs)粒度分布的方法。首先采用微波消解-ICP-MS法测定了纳米抗菌商品中的总银含量,确定样品稀释倍数。然后在SP-ICP-MS模式下,测定3种AgNPs标准样品(30、50和80nm)的粒径,所得结果与供应商提供的TEM值接近,说明SP-ICP-MS法能够准确表征水溶液中AgNPs的粒径分布,同时采用SP-ICP-MS测定了纳米抗菌商品中纳米银颗粒粒径分布。方法简单快速、灵敏度高,能够为纳米抗菌材料中AgNPs表征提供准确的表征方法。     

单颗粒-电感耦合等离子体质谱(ICP-MS)法表征纳米抗菌商品中纳米银颗粒粒径分布

建立了单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定纳米抗菌商品中纳米银颗粒(Silver nanoparticles,AgNPs)粒度分布的方法。首先采用微波消解-ICP-MS法测定了纳米抗菌商品中的总银含量,确定样品稀释倍数。然后在SP-ICP-MS模式下,测定3种AgNPs标准样品(30、50和80nm)的粒径,所得结果与供应商提供的TEM值接近,说明SP-ICP-MS法能够准确表征水溶液中AgNPs的粒径分布,同时采用SP-ICP-MS测定了纳米抗菌商品中纳米银颗粒粒径分布。方法简单快速、灵敏度高,能够为纳米抗菌材料中AgNPs表征提供准确的表征方法。     

超声辅助提取/单颗粒电感耦合等离子体质谱法测定防晒化妆品中的纳米二氧化钛

建立了超声辅助提取/单颗粒电感耦合等离子体质谱(SP-ICP-MS)测定防晒化妆品中纳米TiO_2的方法。考察了停留时间、纳米粒子数量及浓度等分析条件,确定了防晒化妆品中纳米TiO_2的最佳萃取条件以及测定方法,对比了不同萃取溶剂对防晒霜中纳米TiO_2的提取效果。结果表明,在采用0. 1%Tritonx-100(Tx-100)以及5%乙醇作为萃取剂超声辅助提取,测定停留时间为3 ms,待测样品中纳米颗粒的数量浓度低于4×10~7个/mL条件下,该法可准确测定防晒化妆品中的纳米TiO_2,对防晒化妆品中纳米TiO_2的数量浓度检出限(LOD_(conc))为1×10~4个/mL,纳米颗粒粒度检出限(LOD_(size))为35 nm。方法简单快捷、灵敏度高、准确性良好,可同时对防晒化妆品中TiO_2进行浓度测定及粒度分布表征。     

基于单颗粒电感耦合等离子体质谱法测定环境基质水样中纳米银颗粒

采用单颗粒电感耦合等离子体质谱法(SP-ICP-MS)同时测定环境水样中纳米银颗粒(AgNPs)的颗粒浓度、质量浓度和粒径分布,并考察了溶液的pH值、溶解性有机质(DOM)浓度以及离子强度等对AgNPs测定的影响。结果表明:SP-ICP-MS方法对60 nm AgNPs标准溶液的测定结果与标准值一致,准确性较好;pH值(5.0～7.0)、离子强度(≤1 mmol/L)和DOM浓度(≤30 mg/L)对测定结果影响较小;当溶液的pH值≤5.0或离子强度1 mmol/L时,AgNPs的颗粒浓度和粒径随pH值的下降或离子强度的增强而减小。采用SP-ICP-MS方法测定河水、染料废水、养殖废水3种水样中AgNPs的加标回收率分别为98.1%、83.3%和93.3%,表明该方法在合适的基质条件下可用于快速准确测定环境水样中AgNPs的颗粒浓度、质量浓度和粒径分布。     

酶消解-单颗粒电感耦合等离子质谱法测定农产品中纳米铂颗粒

铂纳米颗粒在汽车行业中被广泛用作汽车尾气催化剂。随着铂纳米颗粒在工业生产中的广泛应用,它在环境中广泛分布并可能从植物累积进入食物链中。因此,建立一种在农产品中的定量分析方法是至关重要的。以酶消解的前处理方法结合单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定农产品中纳米铂颗粒(PtNPs)粒径分布及颗粒数量浓度。通过优化前处理提取条件,当Macerozyme R-10酶为10 mg、柠檬酸缓冲溶液浓度为5 mmol/L、提取时间36 h时,农产品中PtNPs提取效果较高。PtNPs粒径检出限为20 nm,颗粒浓度检出限为5×10⁵ particle/L,铂颗粒浓度回收率在(81±3)%~(91±4)%,加标后平均粒径(41±3)~(47±2)nm,与50 nm PtNPs标准溶液粒径接近。方法操作简单、检出限低、准确度高,适用于农产品中PtNPs定量分析,为客观评价农产品铂纳米毒性效应提供可靠的分析技术。     

纳米ATO颗粒粒度分布的脉冲超声波测量研究

讨论了脉冲超声波测量纳米ATO颗粒粒度分布方法中的3个步骤,即超声波衰减谱测量、严格数学模型的选型以及颗粒粒度分布的反演计算.通过发射脉冲超声波并利用变声程方法测量25 ℃时2%(体积分数)的纳米ATO-H2O分散液的超声衰减谱;选取McClements理论模型叠加BLBL理论模型共同描述纳米ATO颗粒分散液中的超声衰减现象;采用最优正则优化反演算法反演得到纳米ATO颗粒的粒度分布以及平均粒径.脉冲超声法检测结果显示,纳米ATO颗粒的平均粒径为25.6 nm,粒度分布为11.4 ～47.1 nm,CPS离心沉降纳米粒度分析仪测定结果分别为22.1 nm和10.1 ～62.6 nm.脉冲超声法检测结果与透射电镜图像以及离心沉降纳米粒度分析仪检测结果吻合较好,证明了脉冲超声波测量纳米颗粒粒度分布以及平均粒径的可行性与可靠性.     

单颗粒-电感耦合等离子体质谱测定金纳米颗粒

单颗粒-电感耦合等离子体质谱法(Single particle-inductively coupled plasma-mass spectrometry,SPICP-MS)是近年出现的一种纳米材料分析方法,可用于表征纳米材料的元素组成、粒径分布以及颗粒物浓度。本研究对比了驻留时间(Dwell time,t_d)和稳定时间(Settling time,t_s)等质谱参数对单颗粒分析结果的影响,分析了金纳米颗粒标准物质(NIST 8012,NIST 8013,GBWE 120127)。结果表明,使用短的驻留时间(0.05 ms)和稳定时间(0 ms),可以获得更高的信噪比,检测到更多的纳米颗粒。利用本方法分析了AuNP标准物质,得到的粒径结果与标准值相符。本方法对金纳米颗粒的数量检出限为1.1×10~5L~(-1),粒径检出限为8 nm。     

光电化学竞争法检测生物素

建立了光电化学系统竞争性检测生物素(Biotin)小分子浓度的方法。采用联吡啶钌[Tris(2,2’-bipyridine)ruthenium,Ru-bpy)]作为标记物,以氧化锡纳米颗粒为电极,草酸盐为电子供体还原标记物。在470 nm光激发下,联吡啶钌的外层电子吸收能量后由基态变为激发态,注入半导体氧化锡纳米颗粒电极的导带,形成光电流信号;草酸盐还原失去电子的联吡啶钌使其恢复初始状态,从而可以再次作为电子供体受激发产生光电流信号。在竞争性检测生物素(Biotin)浓度时,亲和素(Avidin)吸附到氧化锡纳米颗粒电极表面作为识别元件,在浓度大于0.5 g/L时能够达到最大的电极表面覆盖率。1μmol/L Ru-bpy-biotin与不同浓度Biotin组成的混合溶液与电极表面的Avidin发生亲和反应,光激发后检测光电流大小;当溶液中Biotin的浓度增加时,致使与电极表面Avidin结合的Ru-bpy-biotin量减少,在光照射下光电流信号降低。这一竞争性光电检测方法检测Biotin时,检出限为8μg/L。本方法可进一步扩展,应用于有机化合物的竞争性免疫检测。     

无固定相分离-电感耦合等离子体质谱法在环境中痕量金属纳米颗粒分析中的应用

环境中金属纳米颗粒的分析检测不仅需要关注其浓度和化学组成,还需要对其形状、粒径和表面电荷等进行表征。此外,环境中金属纳米颗粒的分析需要解决其低赋存浓度以及复杂基质干扰的难题。无固定相分离技术与电感耦合等离子体质谱(ICP-MS)的在线联用,具有较强的颗粒分离能力和较低的元素检出限,能够快速准确地提供金属纳米颗粒的粒径分布、化学组成等信息,在金属纳米颗粒的分离检测方面表现出极大的潜能。但这一联用技术尚无法获得金属纳米颗粒物的颗粒数浓度和单个颗粒的元素信息,难以判断金属纳米颗粒涂层厚度、纯度以及颗粒的均相/异相团聚行为等。新兴的单颗粒-电感耦合等离子体质谱(SP-ICP-MS)与无固定相分离技术的在线联用,可以获得金属纳米颗粒的流体动力学粒径、元素质量计算粒径和颗粒数浓度等信息,进而弥补无固定相分离与ICP-MS在线联用技术的不足。该文介绍了流体动力色谱、毛细管电泳和场流分离3种常用无固定相分离技术的分离机制和适用检测器,着重综述了无固定相分离技术与ICP-MS/SP-ICP-MS在线联用技术的特点及其在环境金属纳米颗粒分析中的应用。关于场流分离,主要介绍了可以与ICP-MS联用的沉降场流分离和流场流分离。该文还对流体动力色谱、毛细管电泳和流场流分离与ICP-MS在线联用技术的特点进行了比较。最后,该文对无固定相分离技术与ICP-MS/SP-ICP-MS在线联用技术的发展提出了展望。     

酶消解-单颗粒电感耦合等离子体质谱法测定农产品中纳米铂颗粒

铂纳米颗粒在汽车行业中被广泛用作汽车尾气催化剂.随着铂纳米颗粒在工业生产中的广泛应用,它在环境中广泛分布并可能从植物累积进入食物链中.因此,建立一种在农产品中的定量分析方法是至关重要的.以酶消解的前处理方法结合单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定农产品中...     

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.     

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.     

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.     

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.     

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.     

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.     

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.