微波辐射辅助快速检测微量亚硝胺的研究

分析了分光光度法对于溶液中亚硝胺回收率过低的原因,发现去亚硝基化反应 产物NOBr在吹离溶液过程中分解成为光度法无法检测的NO_x（x < 2）鉴于此,在 装置中增加一个CrO_3氧化管,将生成的NO_x（x < 2）转化成可被显色检测的 NO_2,使亚硝胺回收率高于90%,接近公认标准方法－热能分析仪（TEA）法的类似 指标（76% ～ 96%）;而检测限可达2 * 10~(-8) mol/L。发现微波辐射能使亚硝 胺在低于其沸点的温度下挥发和/或分解,并将其用于倩光度法检测,可以在3 min之内将样品中的亚硝胺收集以供测定,形成快速同时检测环境样品（如烟草） 中微量亚硝胺和氮氧化物的新方法。     

高效液相色谱-光水解热裂解-热能分析联用技术测定烟草中的N′-亚硝基去甲烟碱

应用实验室自行设计的高效液相色谱仪-光水解热裂解器-热能分析仪联机装置,建立了一种准确有效的色谱分析方法,用于分离检测烟草中的烟草特有亚硝胺N'-亚硝基去甲烟碱（NNN）、4-亚硝基甲氨基-1-（3-吡啶基）-1-丁酮和另外两种挥发性亚硝胺二甲基亚硝胺、亚硝基吡咯烷。NNN浓度在1~10mg/L时NNN与NaNO2的色谱峰面积比与浓度呈线性关系,绝对检测下限为6ng。用该方法分离并测定了烟草样品中NNN的含量。     

高效液相色谱—光水解热裂解—热能分析联用技术测定烟草中的N‘— …

应用实验室自行设计的高效液相色谱仪－光水解热裂解器－热能分析仪联机装置,建立了一种准确有效的色谱分析方法,用于分离检测烟草中的烟草物有亚硝胺Ｎ＇－亚硝基去甲烟碱（ＮＮＮ）、４－亚硝基甲氨基－１－（３－吡啶基）－１－丁酮和另外两种挥发性亚硝胺二甲基亚硝胺、亚硝基吡咯烷。ＮＮＮ浓度在１～１０ｍｇ／Ｌ时ＮＮＮ与ＮａＮＯ２的色谱峰面积比与浓度呈线性关系,绝对检测下限为６ｎｇ。用该方法分离并测定了烟草样品中     

沸石分子筛吸附和催化降解亚硝胺

综述了近年来国内外在使用沸石和介孔分子筛吸附和催化分解以及检测亚硝胺方面的新进展.亚硝胺属于强致癌物,是吸烟导致癌症的重要原因.本文剖析了沸石对亚硝胺的选择性吸附以及大体积亚硝胺在小微孔沸石上的"嵌入式"吸附模式,探讨了沸石在气相和液相中吸附挥发性亚硝胺的规律和影响因素;研究了介孔分子筛材料对于催化降解烟草特有亚硝胺的高活性,阐述了修饰金属氧化物对于提高沸石吸附或催化分解亚硝胺能力的促进作用,并展望消除亚硝胺污染功能新材料的发展方向.     

烟草与尿样中的代谢标记物

卷烟烟气进入人体后会对人体的代谢物产生影响,目前研究较多的是稠环芳烃类、烟草特有亚硝胺类和尼古丁的代谢物。文章分别介绍了稠环芳烃类代谢物1-羟基芘,烟草特有亚硝胺类代谢物NNAL和NNAL-Gluc,尼古丁的代谢物可天宁,对这些代谢物的检测方法、体内的含量水平、各种条件的影响进行了综述。     

UPLC-MS/MS对卷烟烟气中4种烟草特有亚硝胺的快速测定

建立了卷烟主流烟气中烟草特有亚硝胺的超高效液相色谱-电喷雾串联质谱(UPLC-MS/MS)测定方法。在标准吸烟条件下,采用剑桥滤片收集卷烟烟气粒相物,用醋酸铵缓冲液提取粒相物,经固相萃取净化后,以电喷雾正离子多反应监测方式,实现了烟气中N-亚硝基降烟碱、4-甲基亚硝基吡啶基丁酮、N-亚硝基新烟草碱和N-亚硝基假木贼碱的基线分离和快速测定。4种烟草特有亚硝胺在0~400μg/L范围内具有良好线性,相关系数大于0.998,定量下限为0.08~0.15μg/L,加标回收率为72%~104%,相对标准偏差为3.8%~9.7%。该方法灵敏、快速、准确,适用于卷烟烟气中烟草特有亚硝胺的测定。     

水中挥发性N-亚硝胺的富集、分离净化和气相色谱(FID、ECD)测定

近年来报导,痕迹量(ppb以下)的致癌性N-亚硝胺已从多种食品和环境介质——大气、水、土、烟草烟气及机器加工润滑液中检出。探明水环境中这类致癌物的分布状况及动态变化,就测试方法而言,首先需要解决亚硝胺组分浓度低达超痕量级(ppt)的高效富集法。作为对挥发性亚硝胺筛测和检定的当前最有效     

卷烟主流烟气中烟草特有亚硝胺(TSNAs)的LC-MS/MS测定方法研究

采用0.1mol/L乙酸铵水溶液对捕集卷烟主流烟气中的剑桥滤片进行振荡萃取,过滤后的萃取液直接用高效液相色谱-质谱仪(LC-MS/MS)进行分析。该方法在采用新的液相色谱柱、流动相及梯度洗脱程序后使得四种烟草特有亚硝胺(TSNAs)得到了完全分离,提高了色谱分离的选择性、分辨率和灵敏度。该方法具有前处理简单、分离效果好、分析时间短、检测灵敏度高等优点,实现了对卷烟主流烟气中烟草特有亚硝胺(TS-NAs)的快速、准确测定。     

离子色谱法测定卷烟主流烟气中NO_x与烟丝中NO_3~-含量

<正>烟气中的氮氧化物(NOx)大部分来源于烟草中的硝酸盐(NO3-)[1],一方面由于硝酸盐热分解产生氧气,卷烟中硝酸盐含量增加有助于提高卷烟燃烧性,另一方面由于卷烟主流烟气中NOx的含量主要和烟丝中的NO3-相关[2],随着烟草中硝酸盐含量的增加,主流烟气中N2O、NO、NO2等氮氧化物的释放量也随之增加,NOx是卷烟烟气中主要有害成分之一,被列入了"Hoffmann有害成分名单"     

暴露于环境烟气中的大鼠尿样代谢物分析

4-(甲基亚硝胺基)-1-(3-吡啶基)-1-丁醇(NNAL)是烟草特有亚硝胺4-(甲基亚硝胺基)-1-(3-吡啶)-1-丁酮(NNK)在生物体内的一种代谢标记物,分析暴露于烟气中的生物体内NNAL的含量是研究卷烟烟气对生物体健康影响的有效手段.基于人体的个体差异性很大,本文以饲养的大鼠为研究对象,采用LC-MS/MS...     

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.     

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.     

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.     

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.     

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.