分散液液微萃取-高效液相色谱法测定食品中的维生素A和E

以维生素 A 和 E 萃取率的平均值为检测指标,采用L18(37)正交试验法考察了萃取剂的类型、用量、分散剂的类型、用量以及萃取时间和离子强度6个影响因素,利用高效液相色谱法测定维生素含量.维生素 A 和 E 在0.23～174μg/mL 范围内线性关系良好;定性检出限分别为3.26 ng和7.6 ng(S/N=3);...     

功能性离子液体萃取水溶液中Cu2+:实验与理论

本工作针对含硫脲基咪唑憎水功能离子液体在溶液中Cu²⁺萃取方面的应用及其机理进行研究. 考察了萃取两相体积比、金属离子浓度、时间、无机盐NaCl、溶液pH及离子液体烷基链长等因素的影响. 结果表明: 室温条件下, 0.1 mL离子液体[C_nMPSM][PF₆] (n=4、6、8)与5 mL 21.94 mg/L的氯化铜溶液室温条件下超声混合30 min, 溶液中Cu²⁺的去除率即超过95%; 且此类离子液体对金属离子的萃取效果顺序为: n=4≈n=6>n=8. 以[HMPSM][PF₆]为研究对象, 发现溶液中无机盐NaCl的含量以及溶液pH 对金属离子的萃取效果影响不明显. 与传统离子液体[C_nbim][PF₆] (n=6、8)相比, 硫脲基的引入使其萃取率由20%左右提高到99%, 且有效避免因阳离子交换而引起水中咪唑阳离子含量增加问题. 通过理论计算发现, 功能离子液体对金属离子的萃取依赖于官能团中的S元素与Cu²⁺之间较强的静电及路易斯酸碱作用, 与萃取实验中离子液体未和Cu²⁺发生阳离子交换作用相吻合.     

离子液体[Emim]PF6-邻菲咯琳萃取回收废旧电池中镐、镍离子的研究

研究了疏水性离子液体[Emim] PF_6-邻菲咯琳萃取体系对废旧镍镉电池中镉、镍离子的萃取性能,考察了振荡时间、温度、平衡水相酸度和萃取剂用量时萃取性能的影响.在水相pH值为5.91、温度为80℃时,4.0mL4g/L的邻菲咯琳与3.0mL离子液[Emim] PF_6组成的萃取体系时废旧电池液中镉、镍离子萃取效果良好.同时研究了废旧离子液在不同时间及酸度下的反萃效果,在浓度为1.0mol/L的盐酸介质中反萃1h,镉、镍离子能较好地被反萃.     

超声辅助离子液体液相微萃取-高效液相色谱法分析水样中加替沙星或氟罗沙星

建立了一种采用离子液体1-己基-3-甲基咪唑六氟磷酸([C6mim][PF6])为萃取剂,超声辅助离子液体液相微萃取-高效液相色谱法分析水样中加替沙星和氟罗沙星的方法。 实验考察了溶液酸度、离子液体用量等因素对萃取的影响。在pH值分别为3.3、2.1的加替沙星和氟罗沙星水样中,加入0.4 mL [C6mim][PF6],超声,离心,离子液体相直接用于HPLC进行分析。 该方法的线性范围为0.5~50 mg/L,测定加替沙星和氟罗沙星的相对标准偏差(n=5)为2.80%和5.93%,二者的检出限分别为0.46、0.97 μg/L,该方法萃取水样中加替沙星的加标回收率为80.5%~89.5%,氟罗沙星的加标回收率可达93.3%~99.0%。     

酸性离子液体萃取-氧化模拟油品脱硫研究

以酸性离子液体N-羧甲基吡啶硫酸氢盐(\[CH₂COOHPy\]HSO₄)为萃取剂和催化剂,过氧化氢为氧化剂,用于模拟油品(二苯并噻吩溶于正辛烷配制而成)萃取-氧化脱硫反应,考察过氧化氢用量、离子液体用量、反应温度和反应时间对脱硫率的影响。研究结果表明,当氧硫摩尔比(H₂O₂/S)为6,在10mL模拟油品中加入0.6mL离子液体, 50℃下反应40min,脱硫率可达99.7%。离子液体循环再生使用5次,脱硫率没有明显下降。     

浊点萃取、荧光淬灭法测定痕量维生素B2

根据高聚物的强富集作用及荧光淬灭法灵敏度高等特点,提出了浊点萃取、荧光淬灭法测定痕量维生素B2的新方法。主要研究了萃取剂、萃取时间、酸度、铬蓝黑的浓度、淬灭时间等因素的影响,并探讨了利用维生素B2淬灭铬蓝黑R的机理。实验表明,在最佳条件下,聚乙二醇辛基苯基醚～硫酸铵体系对维生素B2的一次萃取率可达到98%,利用该方法测定维生素B2的线性范围为:1.2×10-7～1.44×10-5g/L;回归方程:ΔF=0.13+3.0C;相关系数为0.9974;检出限:8.4×10-8g/L。该方法用于样品测定,相对标准偏差在2.9%～5.8%之间。     

双水相体系选择性分离富集维生素B_(12)及电热原子吸收法测定

用异丙醇-硫酸铵双水相体系,利用维生素B12的疏水性和硫酸铵的盐析作用,在高浓度无机Co2+共存的情况下可有效地实现维生素B12的选择性分离富集.对双水相体系的组成、萃取时间和pH等实验参数进行了优化,在2.0mL样品、1.1g硫酸铵和200μL异丙醇组成的双水相体系中,对50μgL-1的维生素B12溶液经过萃取分离后富集倍数为11.8.取20μL双水相体系上相进行电热原子吸收检测,线性范围为2～100μgL-1,检出限为0.6μgL-1(3σ,n=11),相对标准偏差为2.8%(50μgL-1,n=9).将所建立的方法应用于功能饮料、保健药片、牛肝等实际样品中维生素B12的含量测定,加标回收率在97%～104%之间.     

室温离子液体超声辅助萃取-高效液相色谱法测定水中菲、荧蒽、芘的研究

以疏水性室温离子液体1-甲基-3-丁基咪唑六氟磷酸为萃取剂,超声辅助同时萃取、富集水中菲、荧蒽、芘为模型的多环芳烃。探讨了不同离子液体、水样体积、超声时间、静置时间等对萃取效果的影响,结果表明:1 mL离子液体萃取含菲、荧蒽、芘各10、60μg/L的40 mL水样,其回收率为:92%~103%,相对标准偏差(n=6)为3.19%~3.85%,方法检出限在1.06~1.25μg/L范围之间。该方法应用于实际河水的检测,结果表明该法快速简便、溶剂用量小,回收率与传统的CH2Cl2萃取相当。     

对称烷基咪唑离子液体单滴微萃取–气质联用测定天然香料中酯类成分

设计合成3种新型对称1,3-二正烷基咪唑六氟磷酸盐离子液体([DCn-IM][PF6],n=4,5,8).研究发现,离子液体热稳定性好,其憎水性和黏度随烷基碳原子数的增加而增加,但密度和极性却逐渐降低.以离子液体为顶空单滴萃取剂,分别考察了不同离子液体对5种酯类化合物的萃取性能.结果表明,离子液体的萃取率既受其黏度、憎水性和极性的影响,还与分析物本身的结构及性质密切相关.[DC4-IM][PF6]的萃取效率明显高于其他离子液体而被确定为萃取剂,并结合气质联用技术对萃取与分析条件进行优化.在0.36 g/mL NaCl溶液中,以1.0μL离子液体40℃萃取分析物35min后,250℃解吸1 min,得到富集倍数为260～1429,检出限为0.46～16.1μg/L.该方法应用于天然香料中5种酯类成分的同时测定,回收率为93.8%～108.9%,表明有高的灵敏度和准确性.     

离子液体单滴顶空微萃取系列乙酯的性能及其气相色谱分析

通过改进气相色谱内衬管,避免离子液体进入色谱柱,实现了离子液体单滴微萃取与气相色谱的联用.利用改进装置考察了离子液体[C4MIM][PF6]对乙酸乙酯、丙酸乙酯、丁酸乙酯、戊酸乙酯、己酸乙酯和苯甲酸乙酯6种乙酯化合物的顶空萃取及气相色谱分析.在优选条件下,即以0.1 μL离子液体在0.36 g/mL NaCl溶液中,以0.1 μL离子液体40 ℃萃取分析物25 min后,气化室解吸1 min,得到富集倍数为3～141, 检出限为0.25～40 μg/L,线性范围约两个数量级,相对标准偏差为3%～8%.本方法装置简单,操作快捷,灵敏度较高,在试样前处理方面有广泛的应用价值.     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.