固相萃取分离-离子色谱法测定化肥中三聚氰胺的含量

采用固相萃取分离-离子色谱法测定化肥中三聚氰胺的含量。化肥样品经10g·L-1三氯乙酸溶液振荡超声提取,离心后,萃取液经阳离子交换固相萃取柱净化。经净化的溶液经IonPac NG1保护柱及Dionex IonPac AS18分离柱分离,以含3mmol·L-1甲基磺酸的乙腈-水(15+85)混合液为淋洗液进行淋洗,所得提取液采用抑制电导检测器进行离子色谱分析。三聚氰胺的质量浓度在5.00~2 000mg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为0.3mg·kg-1。加标回收率在89.7%~97.8%之间,测定值的相对标准偏差(n=6)在1.9%~4.5%之间。     

固相萃取-超高效液相色谱-串联质谱法测定中药和保健食品中13种禁用壮阳类药物含量

固样(2.000 0g)加水10.0mL使其超声分散(液样取2.00mL,加水8.0mL),加甲醇稀释至50.0mL。取上清液2.00mL,用0.1 mol·L-1盐酸溶液稀释至10.0 mL。所得溶液经Cleanert PCX混合型阳离子固相萃取柱净化、氨水-甲醇(5+95)混合液洗脱。洗出液进行色谱分离,用ZORBAX SB-C18色谱柱作固定相,并以不同体积比的乙腈和0.01 mol·L-1乙酸铵溶液(pH 3.5)的混合液为流动相进行梯度淋洗。质谱分析中,采用电喷雾正离子源和多反应监测模式检测。13种壮阳类化合物的质量浓度在1.0~1 000μg·L-1范围内呈线性,方法的检出限(3S/N)在3.0~40μg·kg-1之间。加标回收率为80.1%~111%,相对标准偏差(n=6)小于8%。     

超高效液相色谱-串联质谱法测定畜产品中6种青霉素类药物残留

采用超高效液相色谱-串联质谱法快速测定牛肉和牛奶中青霉素类药物残留。样品以磷酸盐缓冲溶液提取、乙酸锌沉淀蛋白、正己烷脱脂,然后经HLB固相萃取柱净化后,采用超高效液相色谱-串联质谱分离检测,外标法定量。6种青霉素的线性范围均在25.0μg·L-1以内,检出限(3S/N)为2μg·kg-1,测定下限(10S/N)为5μg·kg-1。加标回收率在77.0%~99.8%之间,测定值的相对标准偏差(n=6)在3.7%~13%之间。     

高效液相色谱-串联质谱法测定生鲜乳中三聚氰胺的含量

采用高效液相色谱-串联质谱法测定生鲜乳中三聚氰胺残留量。样品经乙腈溶液超声提取,过Waters Oasis MCX固相萃取小柱净化,50℃氮气吹干,再用1.0mL乙腈溶解后供高效液相色谱-串联质谱分析。以Waters Hilic色谱柱(100 mm×2.1 mm,3μm)为固定相,用乙腈-5mmol·L-1乙酸铵(95+5)溶液洗脱,采用电喷雾正离子模式多反应监测,内标法定量。三聚氰胺的质量浓度在10.0μg·L-1以内呈线性,检出限(3S/N)为0.5μg·kg-1。取空白样品在3个标准加入水平下进行回收和精密度试验,回收率在99.8%~103%之间,测定值的相对标准偏差(n=10)在1.9%~3.2%之间。     

液相色谱-串联质谱法快速测定粮谷中矮壮素和敌草快残留量

提出了粮谷中矮壮素和敌草快的液相色谱-串联质谱分析方法。样品经甲醇-水-乙酸溶液提取后,经HLB固相萃取小柱净化,以Water ACOUITY UPLC BEH C18色谱柱为分离柱,0.1%(体积分数)甲酸-乙腈(20+80)混合溶液为流动相,采用正离子模式监测。矮壮素和敌草快的线性范围均为5.00～500μg.L-1,检出限(3S/N)分别为2.5,5.0μg.kg-1。回收率分别在77.7%～93.1%,73.9%～95.3%之间;测定值的相对标准偏差(n=7)均小于15%。     

凝胶色谱净化-气相色谱-质谱法同时测定烧烤肉制品中19种多环芳烃

提出了凝胶色谱净化-气相色谱-质谱法同时测定烧烤肉中19种多环芳烃含量的方法。烧烤肉样品经正己烷-二氯甲烷(1+1)溶液超声提取30min后,上清液经凝胶色谱净化,所得净化液用HP-5MS色谱柱分离,全扫描模式和选择离子监测模式测定。19种多环芳烃的峰面积与质量浓度在5~200μg·L-1范围内呈线性关系,检出限(3S/N)在0.1~0.5μg·kg-1之间。在20,40,80μg·kg-1 3个浓度水平进行加标回收试验,19种多环芳烃的回收率在58.0%~122%之间,相对标准偏差(n=6)小于21.5%。     

气相色谱法测定食品中仲丁灵残留量

提出了气相色谱法测定食品中仲丁灵残留量的方法。样品用正己烷-丙酮(1+1)混合液提取,提取液经凝胶渗透色谱和固相萃取净化。用DB-1701色谱柱分离,电子捕获检测器测定。仲丁灵的质量浓度在10.0~500μg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为1.4μg·kg-1。添加10,20,50μg·kg-1 3个浓度水平进行加标回收试验,回收率在84.2%~97.2%之间,测定值的相对标准偏差(n=8)在3.8%~15%之间。     

液相色谱-串联质谱法测定虾肉中7种非食用色素的残留量

提出了液相色谱-串联质谱法测定虾肉中7种非食用色素的残留量。样品经过乙腈提取、正己烷脱脂、无水硫酸钠干燥和硅胶固相萃取柱净化。以Agilent Eclipse XDB-C8色谱柱为分离柱,采用电喷雾离子源多反应监测模式检测。采用同位素内标法定量。酸性橙2、颜料红53和酸性金黄G的线性范围在100μg·L-1以内,其余4种色素的线性范围在10μg·L-1以内。酸性橙2、颜料红53和酸性金黄G的测定下限(10S/N)为5μg·kg-1,其余4种色素的测定下限(10S/N)为0.5μg·kg-1。以空白样品为基体进行加标回收试验,所得回收率在53.8%~106%之间,测定值的相对标准偏差(n=6)在2.1%~11%之间。     

液相色谱-串联质谱法同时测定水产品中三苯甲烷类与噻嗪类染料及其代谢产物

采用液相色谱-串联质谱法对鱼肉和虾肉中三苯甲烷类与噻嗪类染料及其代谢物进行测定。样品经对甲苯磺酸-乙酸铵-乙腈溶液提取,正己烷脱脂,二氯甲烷萃取,MCAX固相萃取净化后,以Waters BEH C18色谱柱为分离柱,以0.15%甲酸溶液(含5mmol·L-1乙酸铵溶液)-乙腈混合液为流动相进行梯度洗脱,采用电喷雾正离子源及多反应监测模式进行测定。各化合物的质量浓度在20.0μg·L-1以内呈线性,方法的测定下限(10S/N)均为0.5μg·kg-1。对空白样品进行加标回收试验,回收率在62.6%~108%之间,测定值的相对标准偏差(n=6)在2.0%~14%之间。方法用于鱼肉和虾肉样品的检测,结果与国家标准方法的测定值一致。     

气相色谱-串联质谱法测定烟草中97种农药残留量

利用气相色谱-串联质谱法(GC-MS/MS)检测烟草中97种农药残留。样品以乙腈为溶剂经加速溶剂萃取(ASE),提取液用Carbon-NH2固相萃取小柱净化后,采用VF-5MS色谱柱分离,用电子轰击离子源-多反应监测模式(EI-MRM)检测。97种农药的质量浓度在20~1 000μg·L-1范围内与其峰面积呈线性关系,方法的测定下限(10S/N)在0.02~22.4μg·kg-1之间;在50,100,500μg·kg-1的加标水平下,测得回收率在67.4%~116%之间,测定值的相对标准偏差(n=6)在1.9%~14%之间。     

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.