苯乙烯-二乙烯苯-甲基丙烯酸聚合物微球的制备及其固相萃取性能

以苯乙烯、二乙烯苯和甲基丙烯酸为原料,聚乙烯醇为分散剂,过氧化苯甲酰为引发剂,采用悬浮聚合法制备了具有亲脂和弱阳离子交换性能的球形固相萃取填料,并确定了最佳的聚合反应条件。采用红外光谱和扫描电子显微镜表征了聚合物结构和微球的形貌,通过氮气吸附法测定了填料的比表面积和孔径分布。以氰草津、西玛津、阿特拉津和特丁津4种三嗪类除草剂为目标化合物,通过固相萃取-液相色谱联用技术,考察了样品溶液的酸度、过柱流量及洗脱剂的体积对萃取回收率的影响,确定了最佳固相萃取条件。测定了制备的固相萃取填料的吸附容量和小柱的穿透体积。氰草津、西玛津、阿特拉津和特丁津的检出限分别为0.26,0.63,0.42,0.31μg·L-1。     

气相色谱-质谱法同时测定植物源食品中7种农药的残留量

研究了用气相色谱-质谱法检测草莓和小麦中西玛津、阿特拉津、甲草胺、乙草胺、扑草净、禾草克和哒螨酮的残留量,样品经乙酸乙酯提取,Florisil固相萃取小柱净化,气相色谱-质谱法进行检测,各组分回收率为76．08％-108．1％,测定结果的相对标准偏差为3．9％～10．2％（n=6）。     

环境样品中阿特拉津的检测方法研究进展

综述了2011~2015年内环境样品中阿特拉津残留量分析方法的研究进展,包括液液萃取、固相萃取、固相微萃取、液相微萃取、超声提取、微波辅助萃取等分离方法和气相色谱-质谱、液相色谱-质谱、生物技术等检测方法,以及上述分析方法的应用情况,并对阿特拉津的检测方法的前景进行了展望(引用文献46篇)。     

快速溶剂萃取-气相色谱-质谱法测定土壤中24种半挥发性有机物含量

采用快速溶剂萃取-气相色谱-质谱法测定土壤中24种半挥发性有机物的含量。土壤样品以正己烷-乙酸乙酯(5+1)混合液进行萃取,所得萃取物用弗罗里硅土固相萃取小柱净化。在气相色谱分离中用DB-5MS色谱柱为固定相,在质谱分析中采用选择离子监测模式。24种半挥发性有机物在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限在0.83~4.48μg·kg~(-1)之间,测定下限在3.32~15.8μg·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60.4%~123%之间。测定值的相对标准偏差(n=4)在5.2%~19%之间。     

固相萃取-在线凝胶渗透色谱-气相色谱-质谱法测定豆芽中53种农药残留量

采用固相萃取-在线凝胶渗透色谱-气相色谱-质谱法测定豆芽中53种农药残留量。豆芽样品以乙酸-乙腈(1+99)混合液提取,固相萃取小柱净化,采用在线凝胶渗透色谱-气相色谱分离,在质谱分析中采用选择离子监测模式。53种农药的质量浓度均在0.01~1.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限在0.1~6.0μg·kg-1之间。在20,50,100μg·kg-1等3个浓度水平进行加标回收试验,回收率在72.3%~104%之间,测定值的相对标准偏差(n=6)在1.6%~6.6%之间。     

固相微萃取-气相色谱-质谱法测定橡胶密封圈中8种N-亚硝胺含量

采用固相微萃取-气相色谱-质谱法测定橡胶密封圈中8种N-亚硝胺的含量。按国家标准GB/T 24153-2009进行样品的预处理,然后用二乙烯基苯/聚二甲基硅氧烷萃取头,在30℃和800r·min~(-1)转速的条件下萃取45min。在气相色谱分离中用Agilent 1701色谱柱为固定相;在质谱测定中采用选择离子监测模式。8种N-亚硝胺的线性范围均为0.10~2.0mg·L~(-1),方法的检出限(3S/N)均为0.03mg·kg~(-1)。以空白样品为基体进行加标回收试验,回收率在73.0%~96.1%之间,测定值的相对标准偏差(n=6)在1.3%~9.7%之间。     

环境水体中三嗪和酰胺类除草剂的固相萃取/气相色谱-质谱测定

研究了固相萃取/气相色谱-质谱联用技术测定水样中的12种三嗪类和酰胺类除草剂的方法.比较了两种不同的固相萃取柱MCX和C8对12种除草剂的吸附能力.用C18固相萃取柱萃取分析1 L水样,分别研究了上样速度、pH值、有机改性剂、不同的洗脱溶剂和用量及穿透体积对回收率的影响.用内标法定量,加标质量浓度分别为0.05、0.1、1.0μg/L时,除两种代谢物(去乙基阿特拉津和去异丙基阿特拉津)的回收率相对较低外,其它除草剂的回收率在82%～95%之间,方法检出限为0.010-0.035μg/L,用该方法可实现对环境水体中痕量三嗪和酰胺类除草剂的检测.     

注射式分散固相萃取-气相色谱-串联质谱法测定禽蛋中三聚氰胺北大核心CSCD

采用注射式分散固相萃取-气相色谱-串联质谱法测定禽蛋中三聚氰胺的含量。禽蛋样品用乙腈提取后,加入无水硫酸镁和氯化钠,离心后,上清液用正己烷除脂。以丙基乙二胺和石墨化炭黑为分散固相吸附剂,进行注射式分散固相萃取,过滤后,滤液用氮气吹干后再进行衍生化。在气相色谱分离中采用DB-5MS石英毛细管色谱柱,在质谱分析中采用定时选择性反应监测模式。三聚氰胺的质量浓度在5.0～200.0μg·L^(-1)内与其对应的峰面积呈线性关系,测定下限(10S/N)为2.4～3.5μg·L^(-1)。以空白样品为基体进行加标回收试验,所得回收率为80.3%～103%,测定值的相对标准偏差(n=6)为0.60%～8.9%。     

顶空固相微萃取-气相色谱法测定水中5种农药残留量

采用顶空固相微萃取-气相色谱法测定水中三乙基硫代磷酸酯、阿特拉津、甲基对硫磷、对硫磷和脱叶磷等5种农药残留量。优化的试验条件如下:1聚丙烯酸酯萃取纤维头;2萃取温度为80℃;3萃取时间为40min;4解吸时间为5min。用DB-35MS色谱柱(30m×0.32mm,0.25μm)分离,氮磷检测器检测。5种农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.05~1.0μg·L-1之间。方法用于水库水样分析,加标回收率在37.0%~107%之间,测定值的相对标准偏差(n=5)在1.6%~25.0%之间。     

固相萃取-气相色谱-质谱法测定纺织品中全氟辛烷磺酸盐

采用固相萃取-气相色谱-质谱法测定纺织品中全氟辛烷磺酸盐的含量。纺织品样品在索氏提取器中用甲醇提取后,经固相萃取净化,并用盐酸溶液酸化,再与四丁基氢氧化铵反应。在气相色谱分离中用HP-5MS毛细管柱为固定相,在质谱分析中采用全扫描和选择离子监测模式。全氟辛烷磺酸盐的质量浓度在1.0~30.0mg·kg-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.13mg·kg-1。加标回收率在88.8%~91.1%之间,测定值的相对标准偏差在均小于5.0%。     

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.