模拟唾液浸泡塑料玩具溶出的邻苯二甲酸二(乙基己基)酯的固相微萃取-气相色谱法测定

利用新型溶胶 -凝胶富勒烯C60 涂渍的萃取头 ,采用顶空固相微萃取 -气相色谱法 ,研究了用模拟唾液浸泡塑料玩具溶出的邻苯二甲酸二(乙基己基)酯(DEHP)的固相微萃取(SPME)条件 ,并对聚氯乙烯玩具制品的模拟唾液浸泡液中增塑剂进行了分析和测定 ,方法的检出限为1.02μg/L ,实际样品的检出限为10.2×10-6(w) ,相对标准偏差RSD=10.5 %(n=7)。     

顶空固相微萃取-气相法测定酒中的甲醇和杂醇油

 采用环氧树脂作为固相涂层制作固相微萃取 (SPME)装置 ,建立了顶空固相微萃取 气相法 (HS SPME GC)测定酒精饮料中甲醇和杂醇油的方法 ,并对萃取条件和条件进行了优化。方法的检出限为 0 0 2mg/L～0 0 4mg/L ,相对标准偏差为 1 4 %～ 4 1% ;与顶空气相法相比 ,灵敏度可提高 2 0倍～ 30 0倍。将该法用于啤酒、葡萄酒和保健酒中的甲醇和杂醇油的测定 ,加标回收率为 80 8%～ 110 3% ;与顶空气相法 (国家标准方法 )进行了比较 ,相对误差不大于 7 3%。该法简便、快速、灵敏、精密度好 ,拓宽了SPME的应用范围。     

纳米碳纤维涂层固相微萃取探头的制备及性能分析

采用纳米碳纤维(CNF)作为固相涂层制备了固相微萃取探头(SPME)并进行了评价.该涂层对苯系物(BTX)富集能力强,最高使用温度可达260℃,250℃解析条件下使用50次以上涂层无脱落现象.与活性碳涂层相比,尽管萃取量略小,但其解析时间仅为活性炭的60%,具有更高的精密度和准确度.对BrIX固相微萃取.气相色谱分析结果表明,样品质量浓度在0.1～38.7μg/L范围内与色谱峰面积呈良好线性关系(r=0.9891～0.9940),相对标准偏差为3.9%～5.3%,方法的检出限为2.5×10~(-3)μg/L.     

刻蚀不锈钢丝固相微萃取-高效液相色谱联用测定环境水样中痕量苯并[a]芘

用化学刻蚀法制作了不锈钢丝固相微萃取(SPME)纤维头,与高效液相色谱(HPLC)联用测定了环境水样中的痕量苯并[a]芘(B[a]p),考察了影响SPME的实验参数如萃取时间、解吸时间、萃取温度、搅拌速率和离子强度对萃取效率的影响,建立了测定水样中痕量B[a]p的SPME-HPLC方法。方法的线性范围0.10～4.00 ng/mL,相对标准偏差为7.5%(n=6),检出限为0.04 ng/mL,实际水样的加标回收率90.0%～105.0%。微萃取头机械强度高、寿命长、制作成本低,方法适用于测定环境水样中的痕量B[a]p。     

固相微萃取/高效液相色谱法测定水中的微囊藻毒素

采用CWX/DVB萃取头,应用固相微萃取与高效液相色谱联用技术(SPME/HPLC)分析了水溶液中的痕量微囊藻毒素。对SPME的萃取条件进行了优化,并对实际水样进行了分析。该方法测定MC-LR(LR型微囊藻毒素)的线性范围为1.00~200μg/L,相关系数为0.999 5,检出限为0.45μg/L(3σ,n=11),相对标准偏差(RSD)为2.4%,回收率为90%~99%。该方法测定MC-RR(RR型微囊藻毒素)的线性范围为1.00~100μg/L,相关系数为0.998 8,检出限为0.15μg/L(3σ,n=11),RSD为2.4%,回收率为89%~100%。     

固相微萃取/气相色谱-质谱联用法测定橡胶密封材料中N-亚硝胺

建立了固相微萃取/气相色谱-质谱联用法(SPME/GC-MS)测定橡胶密封材料中N-亚硝基-N-甲基苯胺(NMPh A)、N-亚硝基-N-乙基苯胺(NEPh A)和N-亚硝基二苯基胺(NDPhe A)3种N-亚硝胺化合物含量的方法。样品参考国标GB/T 24153-2009进行预处理后,采用固相微萃取进行提取,对影响固相微萃取效率的纤维涂覆种类、萃取时间、搅拌速度和萃取温度等条件进行优化。在优化条件下,方法的线性范围为5~500μg/L,相关系数(r)均大于0.99,检出限为0.5μg/kg,回收率为77%~92%,相对标准偏差(RSD,n=6)为3.8%~7.7%。     

用C16-MCM-41介孔涂层新型固相微萃取-高效液相色谱分析环境水样中的痕量蒽

首次建立了1种用C16-MCM-41介孔复合材料作纤维涂层的固相微萃取(SPME)与高效液相色谱(HPLC)联用,测定环境水样中痕量葸的方法;对SPME的实验条件,如萃取和解吸时间、萃取温度、搅拌速度以及离子强度等进行了优化;方法的线性范围为0．018—71．2μg.L^-^1,检出限为5．9ng.L^-^1(S／N=3),相对标准偏差为0．033％(RSD,n=7);该法体现了SPME在样品前处理过程中的快速、灵敏、简单和无溶剂的特点。     

溶胶-凝胶固相微萃取涂层及其在农药残留分析中的应用

利用溶胶-凝胶(sol-gel)技术制备固相微萃取(SPME)涂层材料.通过硅醇盐前驱体与涂层聚合物羟基硅油(OH-TSO)的水解共聚的方法,成功地制备了聚二甲基硅氧烷sol-gel 涂层的SPME 萃取头,并以农药的混合标准水溶液为研究对象,用直接-固相微萃取-气相色谱法(GC)对涂层的性能进行考察,制成的萃取头适用于多种农药残留的萃取分离分析.     

基于新型材料的固相微萃取探针的制备与应用

固相微萃取(SPME)是一种简便、快速、绿色的样品前处理方法,近年来引发了广泛关注。固相微萃取探针的萃取相对其萃取选择性和效率起着决定性作用,因此一系列物理化学性质优秀的新型固相微萃取涂层材料应运而生,被用于制备新型固相微萃取探针,以对不同样品基质中的有机小分子进行检测。本文概述了近年来新型SPME探针的研制所依托的新型材料,包括聚合物材料、碳材料、金属有机框架材料等,并重点阐述了相关材料的制备与固定方法、微观结构与萃取性能,以及所制备探针在环境分析、纺织品和皮革分析、食品分析等领域中的应用,并进一步对新型固相微萃取涂层今后的开发方向和应用前景进行了展望。     

顶空固相微萃取-气相色谱质谱法测定蜂蜜中的苯酚残留量

建立了一种顶空固相微萃取-气相色谱质谱法(SPME-GC/MS)测定蜂蜜中苯酚的分析方法。对SPME纤维头、萃取温度、萃取时间及解吸时间等萃取条件进行了优化。结果表明:用85μm的聚丙烯酸酯(PA)萃取涂层对蜂蜜中的苯酚萃取效果很好,苯酚在0.5~1000 ng/g的浓度范围内,方法的检出限为0.1ng/g,相对标准偏差(n=9)为3.3%,平均回收率为85.79%~99.35%。     

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.     

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.