快速制备镍钛合金固相微萃取纤维及其与高效液相色谱联用测定环境水样中的紫外线吸收剂

以镍钛合金丝为基体,通过酸处理方法制得具有大比表面积的固相微萃取(SPME)纤维氧化物涂层。将其与高效液相色谱联用,研究了氧化物涂层对芳香分析物的萃取性能。结果表明,该纤维对所选择的紫外线吸收剂具有良好的萃取效率和选择性。进一步优化了紫外线吸收剂2-羟基-4-甲氧基二苯甲酮(BP-3)、2-乙基己基-4-甲氧基肉桂酸酯(EHMC)、4-(二甲氨基)苯甲酸-2-乙基己酯(OD-PABA)和2-乙基己基水杨酸酯(EHS)的萃取条件。方法在0.1~300μg·L~(-1)范围内具有良好的线性关系,检出限为0.025~0.097μg·L~(-1),使用单支SPME纤维同日内和隔日内的精密度分别为4.9%~5.8%和5.5%~6.4%,使用不同批次SPME纤维的精密度为6.3%~7.1%。所建立方法已成功用于环境水样中目标紫外线吸收剂的富集分离和测定。该纤维制作快速简单、稳定性高,不同批次制作的重现性好。     

漩涡辅助离子液体-分散液液萃取环境水样中的紫外线吸收剂

建立了漩涡辅助离子液体-分散液液萃取(VA-IL-DLLME)的样品前处理技术,并与高效液相色谱联用检测环境水样中的紫外线吸收剂。以1-己基-3-甲基咪唑六氟磷酸为萃取剂,考察了离子液体用量、分散剂种类和用量、漩涡时间、离心时间、稀释剂种类和用量、p H等因素对萃取效率的影响。在最佳萃取条件下,2,4-二羟基二苯甲酮在4~1000 ng/m L、2-羟基-4-甲氧基二苯甲酮在3.5~1000 ng/m L、二苯甲酮,水杨酸-2-乙基己酯和3,3,5-三甲基环己烷水杨酸酯在10~1000 ng/m L浓度范围内具有良好的线性关系(R20.993),检出限为0.8~2.8 ng/m L,相对标准偏差(RSD)为2.6%~7.8%,加标回收率为55.8%~118.9%。方法可用于环境水样中痕量紫外线吸收剂的测定。     

高效液相色谱法测定防晒化妆品中水杨酸酯类紫外线吸收剂的含量

采用高效液相色谱法同时测定防晒化妆品中8种水杨酸酯类紫外线吸收剂(水杨酸乙基己酯、水杨酸三甲环己酯、水杨酸辛酯、水杨酸苯酯、水杨酸异十六酯、水杨酸己酯、水杨酸乙二醇酯和水杨酸苄酯)的含量。1.000 0g样品经5mL乙酸乙酯于20℃超声萃取10min,萃取液在Agilent ZORBAX Eclipse XDB-C_(18)色谱柱上分离,以甲醇-四氢呋喃-0.1%(质量分数)甲酸溶液为流动相进行梯度洗脱,紫外检测波长为340nm。8种水杨酸酯类紫外线吸收剂质量浓度在5.0~100.0mg·L~(-1)内与峰面积呈线性关系,检出限(3S/N)在0.5~2.5mg·kg~(-1)之间;加标回收率在90.6%~98.8%之间,测定值的相对标准偏差(n=6)在1.4%~3.6%之间。     

原位组装TiO2纳米管阵列固相微萃取-高效液相色谱联用测定环境水样中痕量紫外线吸收剂

用阳极氧化法在钛丝表面原位组装了TiO2纳米管阵列(TNTs)作为固相微萃取(SPME)纤维头,TNTs的孔径在100~150 nm之间,壁厚为20~30 nm。与高效液相色谱(HPLC)联用,考察了TNTs-SPME纤维头对水样中痕量紫外线吸收剂的吸附效率,优化了实验条件。所建立TNTs-SPME-HPLC法测定紫外线吸收剂的线性范围为0.2~400μg/L,检出限为0.05~0.37μg/L(S/N=3);对于加标50μg/L的水样平行进行5次测量,同一微萃取头在单日内和隔日间的相对标准偏差(RSD)分别为6.8%~9.2%和10%~13%,重复制作微萃取头的RSD为9.7%~14%。方法用于环境水样分析结果表明,实际水样加标回收率为85.9%~113.2%。所制作微萃取纤维头适用于测定环境水样中的痕量紫外线吸收剂。     

高效液相色谱法测定化妆品中9种防晒剂

采用高效液相色谱法测定化妆品中二苯酮-3、3-亚苄基樟脑、4-甲基苄亚基樟脑、奥克立林、PABA乙基己酯、丁基甲氧基二苯酰基甲烷、甲氧基肉桂酸乙基己酯、水杨酸乙基己酯、胡莫柳酯等9种防晒剂的含量。样品用甲醇提取,以Ultimate XB-C18色谱柱为固定相,用甲醇和水以不同比例混合的溶液为流动相进行梯度洗脱,用二极管阵列检测器测定。9种防晒剂在一定的质量浓度范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在12.5~100mg·kg-1之间。以空白样品为基体进行加标回收试验,所得回收率在87.9%~95.7%之间,测定值的相对标准偏差(n=6)在3.4%~4.5%之间。     

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)。     

高效液相色谱法测定化妆品中防晒剂

采用高效液相色谱法测定化妆品中4种防晒剂p-二甲基氨基苯甲酸乙基己酯、甲氧基肉桂酸乙基己酯、水杨酸乙基己酯和二乙氨基羟苯甲酰基苯甲酸己酯的含量。样品用甲醇超声提取,高速离心10 min,取上清液经0.45μm滤膜过滤后,以HPLC-Cartridge RP-18e色谱柱为固定相,甲醇-水(88+12)混合溶液为流动相进行分离,在350 nm波长检测二乙氨基羟苯甲酰基苯甲酸己酯,在305 nm波长检测p-二甲基氨基苯甲酸乙基己酯、甲氧基肉桂酸乙基己酯和水杨酸乙基己酯。4种防晒剂的峰面积与其质量浓度均在100.0 mg.L-1范围以内呈线性关系,4种防晒剂的检出限(3S/N)在0.015～0.115 mg.L-1范围内,加标回收率在92.8%～105.2%之间,测定值的相对标准偏差(n=6)在1.12%%～2.27%之间。     

气相色谱-质谱法检测涂料中4种苯并三唑类紫外线吸收剂

采用气相色谱-质谱技术对涂料中4种高关注苯并三唑类紫外线吸收剂的含量进行测定。样品风干成膜后以正己烷或乙腈为溶剂进行超声提取,DB-5MS色谱柱(30 m×0.25 mm×0.25μm)分离,SCAN模式进行分析检测。4种苯并三唑类紫外线吸收剂质量浓度在0.5~50μg/m L范围内与峰面积呈线性关系。方法定量下限(S/N=10)为10 mg/kg。加标回收率为84.3%~100.4%,相对标准偏差(RSD,n=6)不大于8.9%。方法适用于涂料中高关注苯并三唑类紫外线吸收剂的日常分析检测。     

螯合-酸性磷萃取剂对铀(VI)的协同萃取

本文研究了螯合-酸性磷协同萃取体系─1-苯基-3-甲基-4-(2'-氯苯甲酰基)-5-吡唑啉酮(PMCBP)与磷酸二(2-乙基己基)酯(HDEHP)和2-乙基己基膦酸-单-2-乙基己基酯(HEHEHP)的氯仿溶液从硫酸介质中对铀(VI)的萃取。实验发现均有明显的协同效应存在。采用斜率法测定了协萃配合物的组成为UO2HA2X和UO2HA2HXX'的混合物, 计算了它们的萃取平衡常数, 讨论了协萃机理。     

含氟硫酸体系HEH/EHP萃取铈(Ⅳ)的动力学研究

采用层流恒界面池法研究了2-乙基己基膦酸单2-乙基己基酯(HEH/EHP)萃取含氟复杂硫酸体系中铈(Ⅳ)的动力学。考察了搅拌速度、水相金属离子浓度、萃取剂浓度、酸度和温度对萃取速率的影响。试验结果表明:萃取反应为一级反应,萃取反应的正向表观活化能为50.8 kJ·mol-1,属于化学反应控制。试验得到萃取动力学方程为R=k[Ce(HF)(HSO4-)3+]1.05[H2A2]2.07[H+]-2.43,并探讨了反应机制。     

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.