固相萃取-三重串联四极杆气相色谱/质谱联用分析蔬菜中43种农药残留留

建立了气相色谱/三重四极杆串联质谱同时分析蔬菜中43种农药残留的方法。采用乙腈提取样品中待测组分,经固相萃取法(SPE)净化后采用气相色谱/三重四极杆串联质谱在多反应监测(MRM)模式下进行外标法定量测定。分别对青菜进行3个水平(10、80、200 μg/kg)的加标回收试验,其回收率为62.2%～170.0%,其中36种农药的回收率为70.0%～120.0%。方法的相对标准偏差(RSD)小于18%,定量限(LOQ)为0.3～4.4 μg/kg。该分析方法背景干扰低,灵敏度高,适合蔬菜中多种农药及杀虫剂残留的测定。     

高效液相色谱法同时测定蔬菜和水果中8种农药残留

建立了同时测定蔬菜和水果中8种农药残留的反相高效液相色谱分析方法.通过乙腈提取,LC-NH2柱净化,C18柱分离,梯度洗脱,检测波长275 nm.8种农药在0.2～10.0 mg/L浓度范围内线性关系良好;检出限在0.01～0.04 mg/kg范围;平均加标回收率在80.1%～103.7%范围,相对标准偏差(RSD)在...     

加速溶剂萃取-在线凝胶渗透色谱-气相色谱-质谱联用法快速测定蔬菜和水果中多农药残留

建立了加速溶剂萃取-在线凝胶渗透色谱-气相色谱-质谱联用(GPC-GC-MS)快速测定蔬菜、水果中代表性农药残留的检测方法。样品经二氯甲烷-丙酮(1:1, v/v)加速溶剂提取,活性炭柱-氨基柱串联净化,氮吹至干,残留物用环己烷-丙酮(7:3, v/v)溶解后经GPC-GC-MS系统以选择离子监测(SIM)模式测定。结果表明,22种农药在各自的线性范围内线性关系良好(相关系数不低于0.9981),检出限(以信噪比(S/N)为3计算)为0.3～1.8 μg/kg,定量限（S/N=10）为1~6 μg/kg。在2种基质(大白菜、苹果)中3个添加水平下的回收率为70.5%～107.5%,相对标准偏差为2.1%～8.7%。该方法提取效率高,定性定量准确、灵敏,可实现对蔬菜、水果中多农药残留的快速检测。     

QuEChERS前处理-液相色谱-串联质谱测定果蔬中18种弱酸性农药残留

建立了液相色谱-串联质谱同时快速测定水果蔬菜中唑菌酮等18种弱酸性农药残留的方法。样品采用1%乙酸-乙腈提取、无水硫酸镁及乙酸钠盐析、C18分散固相萃取净化。考察了唑菌酮在电喷雾离子源的离子化效率,发现在负离子电离模式下加乙酸铵能显著提高唑菌酮的离子化效率。液相色谱以CSH C18色谱柱进行分离,5 mmol/L乙酸铵-乙腈为流动相进行梯度洗脱。质谱分析采用电喷雾负离子电离、多反应监测模式,以基质匹配校准曲线外标法进行定量分析。18种农药在8种基质(青花菜、大葱、胡萝卜、荷兰豆、香菇、苹果、猕猴桃、橙)中3个添加水平(10,20,100μg/kg)的回收率为71.4%~119.7%,相对标准偏差为1.2%~10.0%。18种农药的定量下限(S/N≥10)为0.1~2.0μg/kg。方法简便、灵敏、环保,适用于水果蔬菜中唑菌酮等18种弱酸性农药残留的测定。     

固相萃取-高效液相色谱法同时测定果蔬中9种农药残留

提出了同时测定蔬菜、水果中9种农药残留的高效液相色谱分析方法。样品经乙腈超声提取及Florisil固相萃取柱富集,用正己烷-二氯甲烷(40+60)混合溶剂从柱上洗脱农药残留使净化。洗脱液在40℃氮气吹干,残渣用1.0 mL甲醇溶解,取1μL样品溶液注入高效液相色谱仪测定。采用C18色谱柱分离,以甲醇-水混合溶液为流动相,紫外254 nm检测。结果表明:9种农药的质量浓度在0.01~1.0 mg.L-1范围内呈线性关系,方法的检出限(3S/N)在0.009~0.049 mg.kg-1之间。分别以蔬菜和水果为基体,加入标准溶液进行回收试验,测得蔬菜中9种农药的回收率为68.3%~103.2%,相对标准偏差(n=6)为1.8%~13.9%;水果中农药的回收率为69.4%~106.0%,相对标准偏差(n=6)为2.9%~11.8%。     

液相色谱-串联质谱法测定10种食品中四溴菊酯残留

建立了测定蔬菜、水果、茶叶、大豆等10种食品中四溴菊酯残留的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法。样品以乙酸乙酯(蔬菜、水果、茶叶样品)或乙腈(大豆样品)为提取剂,上层有机相经浓缩、固相萃取小柱净化,流动相定容后,采用HPLC在Agilent ZORBAX Eclipse XDB C18色谱柱上,以甲醇和缓冲盐溶液(0.1%甲酸-10 mmol/L乙酸铵)为流动相进行梯度洗脱分离,以串联质谱在多反应监测(MRM)模式下测定,基质外标法定量。结果表明,四溴菊酯的质量浓度在20～1 000μg/L范围内线性关系良好,相关系数为0.999 8;在0.01、0.02、0.1 mg/kg(粮谷类、茶叶、大豆样品)和0.005、0.01、0.05mg/kg(果蔬类样品)加标水平下的回收率为75%～92%,相对标准偏差(RSDs)为4.0%～12.6%(n=6),定量下限(S/N≥10)为0.01 mg/kg(粮谷类、茶叶、大豆样品)和0.005 mg/kg(果蔬类样品)。该方法不受溴氰菊酯干扰,可直接测定四溴菊酯,克服了以往方法只能测定四溴菊酯和溴氰菊酯总量的不足。     

LC-MS/MS法同时测定4种中草药中155种农药残留

建立了液相色谱-串联质谱(LC-MS/MS)同时测定4种中草药(甘草、银杏叶、菊花和八角茴香)中155种农药残留方法。样品采用乙腈、无水硫酸镁和乙酸钠分散固相萃取(DSPE),再经Cleanert TPH固相萃取(SPE)柱净化,乙腈/甲苯(8:1,V/V)洗脱,液相色谱串联质谱多反应监测模式下测定,外标法定量。实验结果表明,155种农药的检出限(S/N=3)和定量限(S/N=10)范围分别为0.4～34.1μg/kg和1.3～113.7μg/kg;在1.0～2400.0μg/kg浓度范围内,155种农药中有148种农药在4种中草药中线性相关系数平均值R2≥0.9950;在低、中、高3个添加水平,86.5%～97.4%的农药平均回收率在60%～120%范围,94.2%～100.0%的农药相对标准偏差RSD≤20%(n=5)。该方法适用于中草药中农药多残留检测。     

分散固相萃取-超高效液相色谱-串联质谱法同时测定蔬菜中10种新烟碱类农药残留

基于分散固相萃取前处理技术,建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定蔬菜中10种新烟碱类农药的检测方法。样品经乙腈提取,NaCl盐析后,提取液经50 mg C₁₈、 50 mg GCB和200 mg PSA净化,在电喷雾正离子多反应监测模式下测定,外标法定量。结果表明,10种农药在0.1～10.0μg/L范围内均呈良好的线性关系,相关系数(r)均大于0.9955,方法检出限为0.5μg/kg,方法定量限为1.0μg/kg。在1, 5和20μg/kg添加水平下,10种农药的平均回收率为73.5%～119.1%,相对标准偏差在0.60%～11%之间。该方法适用于蔬菜中10种新烟碱类农药的批量快速检测。     

固相萃取-气相色谱/三重四极杆串联质谱分析蔬菜中43种农药残留

建立了气相色谱/三重四极杆串联质谱同时分析蔬菜中43种农药残留的方法。采用乙腈提取样品中待测组分,经固相萃取法(SPE)净化后采用气相色谱/三重四极杆串联质谱在多反应监测(MRM)模式下进行外标法定量测定。分别对青菜进行3个水平(10、80、200μg/kg)的加标回收试验,其回收率为62.2%～170.0%,其中36种农药的回收率为70.0%～120.0%。方法的相对标准偏差(RSD)小于18%,定量限(LOQ)为0.3～4.4μg/kg。该分析方法背景干扰低,灵敏度高,适合蔬菜中多种农药及杀虫剂残留的测定。     

超高效液相色谱-串联质谱法快速测定农产品中残留的种衣剂农药

应用超高效液相色谱-串联质谱(UPLC-MS/MS)联用技术,建立了高灵敏、快速地同时检测农产品中8种种衣剂农药残留量的方法。样品经甲醇-水(体积比为1∶1)提取后,无需经过任何净化过程;以梯度流动相洗脱、经Acquity UPLC C18超高效液相色谱柱分离;电喷雾正离子(ESI+)采集模式、多反应监测模式(MRM)对定量离子和定性离子进行MS/MS测定。8种种衣剂农药在0.001～0.20 mg/L范围内线性关系良好(r≥0.997)。添加浓度为0.006～1.2 mg/kg时,回收率为60%～110%,相对标准偏差小于10%;方法的检出限为0.0005～0.002 mg/kg。该方法仅需约2 min的检测时间,而且灵敏、准确,适合于水果、蔬菜、粮谷等农产品中种衣剂农药残留量的快速、高灵敏地检测分析。     

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.