固相萃取–气相色谱法测定甘草中的六六六、滴滴涕含量

建立了甘草中六六六、滴滴涕农药残留量的固相萃取–气相色谱–ECD测定方法。甘草样品用水浸泡后加入乙腈,以超声辅助振荡提取,采用Florisil固相萃取柱净化,经DB–1毛细管柱(30 m×0.25 mm,0.25μm)分析,进样口温度为220℃,电子捕获检测器温度为320℃。六六六、滴滴涕农药的质量浓度在0.005~0.5μg/m L范围内线性良好,相关系数为0.990 0~0.999 5。在0.05,0.1,0.5 mg/kg 3个添加水平下,2种农药共8个异构体加标回收率为60.1%~122.2%,相对标准偏差为2.3%~15.1%(n=5),检出限为0.25~1.4μg/kg,定量下限为0.56~3.06μg/kg。该方法具有样品前处理操作简单、灵敏度高、试剂用量少、选择性高、重现性好等优点,适用于甘草中六六六、滴滴涕农药残留量的快速测定。     

气相色谱-串联质谱同位素内标法测定中草药中124种农药及其代谢物残留

建立测定中草药中124种农药及其代谢物残留的气相色谱-串联质谱(GC-MS-MS)方法。采用同位素内标法,样品经乙腈提取,采用混合型固相分散萃取剂净化,加入分析保护剂校正基质效应。色谱柱为DB-5MS(30 m×0.25 mm×0.25μm),程序升温,GC-MS-MS测定。124种农药残留在0.005~0.40μg/m L内呈线性关系,在0.06~0.3 mg/kg内的平均回收率为84.8%~108.7%,RSD为2.1%~12%,方法检出限(LOD)为0.005~0.013 mg/kg。该方法适合于中草药中农药多残留的同时检测。     

固相萃取-气相色谱-质谱法测定果蔬中36种农药残留

采用气相色谱-质谱法测定果蔬中36种农药残留。果蔬试样经丙酮-水匀质,二氯甲烷液-液萃取,然后过石墨化炭黑固相萃取柱净化,浓缩定容后在DB-5毛细管色谱柱(30 m×0.25 mm,0.25μm)分离,质谱中选择电喷雾离子源-选择离子监测模式。36种农药残留的质量浓度在一定范围内与其峰面积呈线性关系,检出限(3S/N)均不高于15μg·kg-1。加标回收率在75.3%~115%之间,测定值的相对标准偏差(n=6)在0.6%~7.8%之间。     

气相色谱-质谱-选择离子监测法测定漱口水中挥发性成分的含量

建立了Listerine漱口水中挥发性成分的GC-MS/SIM定量检测方法。采用HP-5MS 5 Phenyl-Methyl Siloxane(30 m×0.25 mm×0.25 m)弹性石英毛细管柱,80℃~250℃程序升温,以联苯作为内标物,采用GC-MS的全扫描方式(Full Scan)和选择离子检测方式(SIM)对漱口水中桉叶油素、薄荷醇、水杨酸甲酯和麝香草酚进行定性和定量分析。桉叶油素、薄荷醇、水杨酸甲酯和麝香草酚线性范围分别为1.15~276μg/m L(r=0.9979),1.23~299.16μg/m L(r=0.9997),1.47~354μg/m L(r=0.9998),1.24~299.4μg/m L(r=0.9989);检出限(LOD)分别为12.4,12.4,11.5,14.8 ng/m L;平均回收率为92%~109%,RSD为4.1%~5.0%。     

改良的QuEChERS-气相色谱-质谱联用法测定茶叶中多种农药残留

建立了以QuEChERS作为前处理方法,气相色谱/质谱联用法同时测定茶叶中33种农药残留的检测方法。样品经改进的QuEChERS法进行提取净化,采用DB-5MS(30m×0.25mm×0.25μm)毛细管色谱柱分离,选择离子模式下同时测定,外标法定量。33种农药残留在0.01~3.00mg/L范围内线性关系良好,相关系数均大于0.999。方法的检出限为4.0~35μg/kg,样品平均添加回收率为82.7%~103.8%,相对标准偏差为0.73%~6.8%。方法适用于茶叶中毒死蜱、联苯菊酯等33种不同类型农药残留的同时检测。     

超低温溶剂提取-全二维气相色谱/飞行时间质谱法测定卷烟主流烟气中有机酸成分

建立了超低温溶剂提取结合全二维气相色谱/飞行时间质谱(GC×GC-TOF/MS)测定卷烟主流烟气中有机酸类成分的方法。首先利用乙醚为提取溶剂的超低温溶剂提取装置对卷烟主流烟气进行捕集,然后将提取液通过液液萃取、N,O-双(三甲基硅烷)三氟乙酰胺(BSTFA)衍生化后,以DB-1(30 m×0.25 mm,1.0μm)为一维色谱柱、DB-wax(1.5 m×0.1 mm,0.1μm)为二维色谱柱组成的柱系统对目标物进行分离,在调制周期为6 s、质量扫描范围为m/z 45~450的条件下,卷烟主流烟气中12种有机酸成分可以在58 min内得到准确的检测。实验结果表明,卷烟主流烟气中12种有机酸标准曲线相关系数R2>0.99,加标回收率为80.2%~107.8%,相对标准偏差(RSD)的范围为0.4%~12.1%(n=5),方法检出限为1.3~24.5μg/kg,定量限为4.1~77.1μg/kg。     

气相色谱-质谱法检测洗涤用品中高关注物质卡拉花醛及其同分异构体

采用气相色谱-质谱(GC-MS)技术对洗涤用品中卡拉花醛及其同分异构体的总含量进行测定。样品以甲醇为溶剂进行超声提取,经DB-5MS(30 m×0.25 mm×0.25μm)色谱柱分离,SCAN模式进行分析检测。通过气相色谱法确定标准溶液中卡拉花醛及其同分异构体的比例,在5~100 mg/L浓度范围内建立标准曲线。方法定量下限(S/N=10)为0.25 mg/g,加标回收率为97.4%~111.5%,相对标准偏差(RSD,n=6)为3.7%~7.2%。该方法快速简便、准确可靠,适用于洗涤用品中卡拉花醛及其同分异构体的日常分析检测。     

气相色谱-串联质谱检测鹅组织中哌嗪残留

建立了鹅组织(肌肉、肝脏、肾脏以及皮肤和脂肪)中哌嗪残留的气相色谱-串联质谱检测法。鹅组织经加速溶剂萃取(ASE350),乙腈提取,过Strata-X-C固相萃取小柱净化后的样品在乙酸酐和三乙胺条件下衍生。衍生产物经气相色谱-串联质谱仪(GC-MS/MS)检测,色谱柱为TG-5MS Amine(30 m×0.25 mm i.d.,0.25μm),载气为氦气,进样口和检测器温度均为280℃。采用EI模式,SCAN和SIM扫描定性,Auto SRM结合外标法定量。哌嗪添加量在5.1~2.5×10~3μg/kg范围内,线性关系良好,相关系数为0.9995。在定量限(LOQ:5.1,5.2,5.2,5.2)~2.0×10~3μg/kg的加标水平上,鹅组织中哌嗪的平均回收率为85.2%~95.5%,相对标准偏差(RSD)为1.6%~4.7%,日内RSD为1.2%~5.3%,日间RSD为2.0%~7.7%。检测限(LOD)和定量限(LOQ)分别在1.4~1.6μg/kg(S/N≥3)和5.1~5.2μg/kg(S/N≥10)之间。方法适用于鹅组织中哌嗪残留的检测。     

毛细管气相色谱法测定沉香中20种有机氯农药残留量

应用毛细管气相色谱法测定沉香中20种有机氯农药的残留量。样品以乙酸乙酯提取,提取液用凝胶色谱-固相萃取(GPC-SEP)进行净化。采用DB-1701P石英毛细管色谱柱(30m×0.25mm,0.25μm)分离样品,电子捕获检测器进行检测。20种有机氯农药的线性范围均为1~50μg·L-1,检出限均为0.1μg·kg-1。方法用于沉香样品分析,加标回收率在95.8%~114%之间,测定值的相对标准偏差(n=6)在0.3%~3.8%之间。     

静态顶空-气相色谱法测定养殖用水中11种氯苯类化合物

提出了静态顶空-气相色谱法测定养殖用水中11种氯苯类化合物的方法。取10mL含200g·L-1氯化钠的水样在20mL顶空瓶中于70℃振摇30min进行顶空进样的条件优化。选用DB-35MS毛细管气相色谱柱(30m×0.25mm,0.25μm)分离,电子捕获检测器检测,外标法或标准加入法定量。在优化条件下,二氯苯、三氯苯、四氯苯的线性范围分别为0.16~8μg·L-1,0.017 6~0.88μg·L-1,0.004~0.2μg·L-1,五氯苯和六氯苯的线性范围均为0.001~0.05μg·L-1。11种氯苯类化合物检出限(3S/N)为0.0002~0.04μg·L-1,应用此方法对养殖用水进行测定,回收率在86.0%~106%之间,测定值的相对标准偏差(n=5)在2.1%~5.8%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.