稀土元素分离检测技术新进展

对2003年以来稀土元素分离检测技术的新进展进行了评述，重点集中于各种新型分离技术、新型检测技术及其在稀土元素分析中的应用。对于离子液体、纳米材料、离子印迹聚合物等新型材料以及浊点萃取、膜萃取、毛细管电泳等新型技术在稀士元素分离中的应用进行了详细讨论，并对中子活化分析、等离子体原子发射光谱和等离子体质谱在稀土元素检测中的应用进行了综述，重点讨论了等离子体质谱技术的应用。在回顾稀土元素分离检测技术进展的同时，对其在未来几年的发展趋势进行了评述。     

大体积进样技术在气相色谱-质谱法测定 二英类化合物中的应用

利用大体积进样技术(large volume injection,LVI),结合气相色谱-质谱方法对二英的测定效果进行了研究。同时与传统分流/不分流进样技术进行了对比。对进样体积为1,5,10,25,50和100 μL的色谱图进行了分析。研究表明使用大体积进样方式,在不影响色谱分离度的同时,大幅度提高了分析灵敏度。通过对土壤样品的检测,证明该方法可以用于环境样品的实际测定。     

固体进样元素分析技术在农业领域的应用

重金属是农产品、农田土壤、肥料、饲料等农业样品中的重要污染物,传统的实验室分析方法需繁琐的前处理,耗时费力,无法满足重金属的快速检测需求。固体进样元素分析技术具有简化样品前处理、便捷、绿色、高效等优势,在农业领域中元素的快速检测分析中具有良好的应用前景。通过对固体进样元素分析技术,包括样品导入技术和电热蒸发、电感加热、激光烧蚀、X射线荧光光谱、激光诱导击穿光谱等固体进样分析系统进行综述,并对这些技术在农业领域中的应用做了进一步的梳理。固体进样分析技术已在农业样品中元素的快速检测、现场监测、风险评估等工作中发挥着举足轻重的作用,相信随着仪器研发、材料科学、机器学习等新兴技术的快速发展,其结构小巧、使用简单、分析迅速等优势将会充分发挥,为农业领域中质量安全监管提供一种更为有效、可靠的快速检测手段。     

纳米金辅助介质阻挡放电离子化质谱分析法在兽药饲料快检中的应用

介质阻挡放电离子化质谱分析法具有无需复杂样品前处理、分析速度快等优点,可实现样品原位、高效检测,成为质谱分析领域的热点技术。本研究提出了一种基于纳米金辅助纸基进样方式的介质阻挡放电离子源-质谱(DBDI-MS)联用技术,实现了氟甲喹、二甲氧苄啶、替硝唑、地美硝唑共4种兽药的快速检测。结果表明,在氦气流量为2.5 L/min、离子源温度为200℃等最优实验条件下,4种兽药检测信号强度均比无纳米金辅助时提高了8~31倍。4种兽药样品在各自的浓度范围内有较好的线性关系,相关系数(r)为0.952~0.996,且在饲料基质中的加标回收率为79.4%~96.5%。本方法能快速检测兽药饲料,具有灵敏度高、检测费用低、实用性好等优点,所得结果基本满足农业部限定标准要求,适合现场检测,在饲料质量控制方面具有较好的应用前景。     

快速测量挥发性有机物的膜进样-飞行时间质谱仪的设计和应用

研制了一种膜进样-微型飞行时间质谱仪, 该仪器使用双层50 μm硅橡胶膜作为大气压下直接进样的接口. 实验结果表明, 随着样品流速的提高, 膜富集效率信号强度呈线性提高. 双膜中间具有真空差分系统, 富集得到的样品被迅速抽走, 进样系统中样品无记忆效应. 样品在膜中的响应时间为100 s, 而打开差分系统后仅需10 s信号即下降为平稳状态. 与毛细管直接进样相比, 双层膜的富集作用显著, 在相同的实验条件下使用膜进样技术测定10×10-6 (体积分数)苯、甲苯和对二甲苯的信号强度分别提高了280, 370和600倍. 膜进样系统与真空紫外光软电离方式联用, 对于苯的检出限已经达到了25×10-9 (体积分数), 线性范围为3个数量级. 由于采用了软电离方法, 无碎片离子产生, 所以能够根据分子量进行快速定性分析. 将该仪器应用于香烟主烟气中可挥发性有机物的在线分析, 得到50多种可挥发性的有机物. 实验结果表明, 膜进样-飞行时间质谱将在在线分析(特别是环境监测)方面具有广泛的应用空间.     

微量生物样品中糖蛋白N-糖链电喷雾电离质谱分析前处理方法的建立

基于电喷雾电离质谱检测技术,建立了一种可靠、高效、简单,适合于微量糖蛋白N-糖链解离、富集纯化的方法.以糖蛋白牛胰核糖核酸酶(Rib B)和卵清白蛋白(OVA)为模型蛋白直接酶解,比较了4种方法纯化酶解样品的效果.比较了直接酶解和经过聚偏氟乙烯(PVDF)膜富集后酶解微量复杂生物来源样品胎牛血清的酶解效果,最终建立了微量生物样品中糖蛋白N-糖链的质谱分析前处理方法.采用PVDF膜吸附复杂生物样品中的糖蛋白,N-糖苷酶F(PNGase F)酶直接在膜上完成糖链释放(37℃,24 h),采用微晶纤维素柱结合石墨碳柱对糖链进行富集纯化,用于微克级胎牛血清和健康人血清中N-糖链质谱分析的前处理.本方法通用性好,在微量生物样品糖链质谱分析检测的前处理方面具有一定应用价值.     

复杂样品质谱分析技术的原理与应用

原位、实时、在线、非破坏、高通量、低耗损的质谱学方法是质谱分析技术发展的重要趋势.在无需样品预处理的条件下对复杂基体样品中痕量待测物直接离子化技术的出现,极大地提高了质谱分析的效率,使实际样品的快速质谱分析成为可能.本文着重综述了能够在无需样品预处理情况下对复杂基体样品离子化的新兴质谱技术及其应用研究,系统阐述了直接离子化技术的基本原理和方法,介绍了几种典型的常压直接离子化技术和装置,对直接离子化质谱分析技术在食品、药品、环境、活体分析、代谢组学、蛋白质组学以及生物组织质谱成像等领域的典型应用进行了述评,讨论了提高复杂样品快速质谱分析选择性的可能方法,并展望了常压直接离子化技术未来发展的可能趋势.     

在线富集二维毛细管电泳分析新体系检测尿样中药物及对映体

将在线富集技术同二维(2D)毛细管电泳(CE)分离相结合同时提高复杂样品中痕量组分的分离度和检测灵敏度.毛细管区带电泳(CZE)作为第一维,分析物根据淌度不同进行分离,第一维流出组分进入第二维毛细管,根据分配系数不同进行胶束电动毛细管色谱(MEKC)分离.采用阳离子选择性耗尽进样(CSEI)在柱预富集,延长进样时间,增大进样量;同时在二维毛细管接口处采用动态pH联接/胶束扫集在线富集技术不仅避免第一维分离组分在接口处扩散,还可进一步压缩样品区带.同常规电动进样CE分离相比,该在线富集二维分离技术的分离能力远远高于一维CZE或MEKC分离,富集倍数达到(0.5～1.2)×104.该法成功应用于人体尿样中四种药物及对映体的分析测定,浓度检出限为0.1～0.3μg/L.进一步研究了人体尿样中四种药物24h内的药代动力学规律.     

毛细管电色谱联用技术的研究进展

毛细管电色谱(CEC)作为一种新型微柱分离技术,具有高效、高选择性、高分辨率和快速分离等特点。由于CEC进样体积通常为纳升级,所以对检测系统的高灵敏检测提出了很高的要求。当前,发展CEC与各种高灵敏检测器的联用已成为CEC研究中最活跃的方向之一。本文简要介绍了CEC研究的发展历程,系统综述了CEC与各类检测器联用技术及其在复杂样品分离分析中应用的最新进展,并对CEC联用技术的前景进行了展望。引用文献141篇。     

碳纤维离子化质谱技术的研究与应用

碳纤维离子化技术是一种新型敞开式质谱技术,可在开放式大气压环境下对各种形态的样品或样品表面物质进行检测,其分析成本低、通量高、简便、实时、快速,简化了工作流程,降低了样品的基质效应。该文从碳纤维离子化质谱技术的原理出发,介绍了影响其电离效率的主要因素,如碳纤维形态、碳纤维温度、碳纤维上所加电压、碳纤维与离子进样口的距离以及样品添加的方式,并对该技术近几年的改进和发展,及其在食品药品、法医毒物及生物样品、品种鉴别和环境分析等领域的应用进行了综述,详细介绍了其特点和优势。最后讨论了碳纤维离子化质谱技术存在的不足,以及未来可能的研究方向。     

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.