环境舱-热脱附-气相色谱/质谱联用法测定软体家具面料中40种挥发性有机物

建立了同时检测软体家具面料中40种挥发性有机物的环境舱-热脱附-气质联用(ETC-ATD-GC/MS)检测方法。以Tenax TA吸附管吸附环境舱内不同面料中释放的挥发性有机物,经热脱附仪加热,将挥发性有机物脱附后随载气进入GC/MS进行定性和定量分析。考察了吸附管脱附温度、脱附时间,冷阱温度等不同参数对挥发性有机物的脱附效率的影响。结果表明,40种挥发性有机物在2~200 ng质量范围内呈良好的线性关系,相关系数在09949~0.9999之间,方法的检测限为0.011~0.277μg/m~3。方法回收率为88.0%~109.9%,相对标准偏差在1.5%~9.5%之间。方法适用于不同软体家具面料中挥发性有机物的定量分析。     

电冷阱富集-光电离移动质谱快速检测痕量挥发性有机物

采用电动制冷机设计并搭建了一套低温富集-高温解析冷阱装置,与光电离移动质谱联用,实现了大气中痕量挥发性有机物(VOCs)快速、自动富集检测。与传统冷阱制冷方式相比,电动制冷机低温可至!196℃,体积小巧、无制冷剂消耗、便于携带。利用冷阱结合在线质谱分析了苯、甲苯和二甲苯混合气,对冷阱各参数进行了优化,结果表明:冷阱富集后苯、甲苯和二甲苯的信号强度分别提高了212、254和242倍,回收率分别达到98%、87%和85%,单样品分析时间14 min。将电冷阱结合移动式在线质谱直接分析含有39种VOCs的EPA TO-14标准混合气和室内环境空气,仪器灵敏度低于国家对室内空气中VOCs阈值。电冷阱富集在线移动式质谱可以实现大气、室内环境中痕量VOCs快速富集检测,在挥发性有机污染物现场、实时监测中具有重要的应用潜力。     

热脱附-吹扫捕集-气相色谱质谱联用在大气挥发性有机物分析中的应用探索

采用热脱附结合吹扫捕集(P&T)技术对大气中挥发性有机物(VOCs)进行富集,并用气相色谱质谱(GC/MS)进行分析检测,建立了一种大气中多组分VOCs分析方法。将热脱附-吹扫捕集-气相色谱质谱联用技术应用于大气挥发性有机物分析中,使样品经过吸附管及捕集阱双重富集后再进入GC/MS检测,VOCs分析结果部分目标物检出限可达到0.1 ng/L,实际平行样品检测结果相对偏差小于30%,且可同时对54种VOCs进行定性定量分析。     

利用热脱附/冷阱捕集提取土壤中挥发性有机物的条件研究

采用热脱附/冷阱捕集提取土壤中的挥发性有机物,以17种VOCs作为目标研究对象进行挥发性有机物的提取条件研究。试验确定的提取条件为:热脱附温度300℃,热脱附时间3 min,冷阱捕集温度–10℃。优化条件后添加水平为1 mg/kg的加标土壤样品测定结果在0.75～0.94 mg/kg之间,相对标准偏差为2.89%～7.16%。     

自制炭阱吸附装置与气相色谱-质谱联用测定植物的挥发性有机物

设计组装了炭阱吸附装置,并与气相色谱-质谱(GC-MS)联用测定了银杏叶和利马豆的挥发性有机物。采用炭阱吸附装置与固相微萃取(SPME)收集银杏叶的挥发性有机物,用GC-MS进行分析,结果表明采用炭阱吸附装置对银杏叶挥发性有机物的富集效果优于SPME方法。实验还采用内标法对利马豆的挥发性有机物进行了初步的定量,两次实验结果的重复性较好。由于炭阱吸附装置能够很好地收集植物的挥发性有机物,且可以进行多个样品的平行实验及植物挥发性有机物的定量研究,因此炭阱吸附装置与GC-MS联用更适合用于实验室中植物挥发性有机物的研究。     

热解析-气相色谱或气相色谱-质谱法分析大气可吸入颗粒物中的半挥发性有机化合物

研制了一种热解析装置,并与气相色谱或气相色谱-质谱联用,定性定量分析了大气可吸入颗粒物中的半挥发性有机物。装置为直热式加热,升温速率快;直接安装在色谱进样器上方,无需冷阱聚焦。将热解析装置与气相色谱联用,优化了样品承载体材质、热解析条件和进样模式,并用于16种多环芳烃和9种正构烷烃的检测。结果表明,热解析-气相色谱方法对多环芳烃和正构烷烃的检出限分别为0.014~0.093 ng和0.016~0.026 ng,线性相关系数大于0.9975;用于3个城市PM10中的痕量多环芳烃和正构烷烃的定量测定,回收率分别在95%~135%(多环芳烃)和95%~115%(正构烷烃)之间。将热解析装置与气相色谱-质谱联用,比较了3个城市7种粒径分布的PMx(x=10,5,2,1,0.5,0.25,0.1)中的多环芳烃和正构烷烃,结果表明,不同粒径颗粒物均含有正构烷烃和PAHs,但含量相差很大。     

热脱附-冷阱捕集-气相色谱-质谱法测定空气中34种挥发性有机物

采用热脱附-冷阱捕集-气相色谱-质谱法测定空气中34种挥发性有机物的含量。利用冷阱捕集技术对空气样品进行富集,然后加热解吸。在气相色谱分离中用DB-624UI色谱柱为固定相,在质谱分析中采用选择离子监测模式。34种挥发性有机物均在一定的质量范围内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.004~0.500ng·L~(-1)。加标回收率为69.8%~118%,测定值的相对标准偏差(n=6)为2.9%~6.3%。     

热脱附/冷阱捕集–气相色谱法同时测定空气中多种挥发性有机物

使用Tanax-TA管富集样品,建立热脱附/冷阱捕集–气相色谱法同时测定工作场所空气中苯系物、丙酮、丁酮、乙酸乙酯、乙酸丁酯等12种常见挥发性有机物分析方法。该法线性范围为5~100μg/m L,相关系数不小于0.999 0。12种挥发性有机物的检出限为3.0×10~(–4)~1.7×10~(–3) mg/m~3(以采样体积为1 L计),加标回收率为80.9%~106.5%,测定结果的相对标准偏差为2.08%~4.09%(n=10)。该法样品处理简单,可应用于工作场所空气中挥发性有机物的快速测定。     

胸腔积液中低沸点VOCs的SPME-冷阱聚焦-GC/MS分析

建立了良恶性胸腔积液样品中低沸点挥发性有机物(VOCs)的顶空固相微萃取-冷阱聚焦-气相色谱质谱联用(SPME-Cryo Trap-GC/MS)分析方法。应用冷阱聚焦技术后,胸腔积液中低沸点的VOCs得到了很好的分离。对26例样品(10例恶性和16例良性样品)进行了分析,得到76个挥发性物质。以环戊酮为内标求得其中检出频率较高的27种物质的相对峰面积,并对其在恶性组和良性组中的平均值进行计算与比较。丙酮、环己醇、环己酮和2-乙基-1-己醇这4个物质在恶性组中的峰面积平均值明显高于良性组,表现出较大差异。方法适于良恶性胸腔积液中挥发性有机物的比较分析,为肺癌潜在标志物的筛选提供了参考。     

海水和大气中挥发性硫化物分析方法的研究

建立了大气和海水中挥发性硫化物的气相色谱分析方法,确定了最佳实验条件.为了适应不同的基质和保存方式,大气和海水样品采用了不同的分析方法.测定大气样品时,采用大气采样罐及三级冷阱预浓缩气相色谱-质谱联用技术,而海水样品采用吹扫捕集-气相色谱测定.本方法测定大气挥发性硫化物的线性范围较好,精密度为7.7%~15.1%,检出限为0.23~4.7 ng;海水中挥发性硫化物的精密度为3.5%~5.3%,检出限为2.5~3.5 ng.将本方法用于青岛近海海水和大气中硫化物的测定,测得海水中羰基硫、二甲基硫和二硫化碳的平均浓度分别为(268±58)pmol/L、(1264±0.2)pmol/L、(19±2)pmol/L,大气中的平均浓度为543±39、39±9和56±20(×10-12,V/V).本方法可准确测定海洋环境中的挥发性硫化物.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.