磷酸处理-气相色谱法测定含硫蔬菜中的多种有机氯及拟除虫菊酯类农药残留

建立了含硫蔬菜(青葱、洋葱、大蒜、蒜苔、韭菜等)中多种有机氯和拟除虫菊酯类农药残留的测定方法。采用10%磷酸处理含硫蔬菜,去除含硫化合物的干扰,再用1∶1的丙酮-正己烷提取,加入2%的硫酸钠溶液用正己烷进行液液分配,提取液用硅镁吸附剂层析柱净化,用气相色谱-电子俘获检测器检测。样品加标回收率在78.0%~97.8%之间,相对标准偏差在3.0%~9.6%之间。该方法的检出限为有机氯农药0.001 mg/kg,联苯菊酯、甲氰菊酯和三氟氯氰菊酯为0.002 mg/kg,其余五种拟除虫菊酯类农药0.005 mg/kg。     

蔬菜农药多残留分析中基质共提物净化方法的研究

首次建立了蔬菜中常见基质干扰物的净化方法.用GC-MS分析样品提取液、确定了蔬菜农药多残留检测常见的基质干扰物.建立常见吸附剂对基质干扰物的吸附模型,以及吸附剂对农药的吸附模型.据此建立了番茄、油菜和尖椒3种蔬菜中102种农药多残留SPE净化方法和气相色谱-质谱/选择离子存储检测方法(gas chromatography-ion trap mass spectrometry/selective ion storage, GC-MS/SIS).样品用凝胶渗透色谱(GPC)去除大分子干扰物和部分色素和(或)采用石墨化碳黑(GCB) Florisil混合SPE柱去除色素和脂肪酸.在0.02 mg/kg和0.10 mg/kg两个水平,农药添加回收率为65% ～123%(除久效磷、抗蚜威和蝇毒磷),RSD不大于15%.方法检出限在2 ～30 μg/kg范围.对于其它蔬菜,只要确定样品中的基质干扰物,即可选择合适的吸附剂制备专用的SPE柱.该方法适用于含色素、脂肪酸和大分子干扰物蔬菜样品中的农药多残留分析.     

基于壳聚糖的QuEChERS-气相色谱-串联质谱法测定人参中30种农药残留

建立了一种以壳聚糖为净化材料的QuEChERS-气相色谱-串联质谱检测人参中30种农药残留的检测方法。探究了吸附剂及其用量对样品提取和净化效果的影响,确定壳聚糖为吸附剂净化。采用选择离子监测(SRM)模式,基质匹配标准曲线外标法定量。30种农药在各自的浓度范围内,线性关系良好(r> 0.996);检出限范围为1.5~3.0μg/kg,定量限范围为5.0~10.0μg/kg。3个添加水平(10,20,100μg/kg)的回收率在84.1%~113.7%之间,相对标准偏差均小于15%。该方法适用于检测人参中农药残留。     

气相色谱-负化学源质谱法测定豆类中14种农药残留

建立了以凝胶渗透色谱(GPC)和固相萃取法净化、气相色谱-负化学离子源-质谱(GC-NCI-MS)联用法测定豆类(毛豆、荷兰豆、豌豆、蚕豆等)中14种农药残留的分析方法。样品经提取液经GPC净化除去大部分的油脂和色素,再经乙二胺-N-丙基甲硅烷(PSA)小柱净化,目标农药采用GC-NCI-MS检测,外标法定量。添加50μg/kg浓度水平时,农药回收率在42.2%~124.5%之间,相对标准偏差在1.10%~8.72%之间;农药的检测限在0.5~10.0μg/kg(3倍信噪比)之间。方法净化效果好,灵敏度高,可满足进出口豆类农药多残留检测实际工作的需要。     

气质联机分析蔬菜中农药多残留及基质效应的补偿

摘要建立了蔬菜中52种农药化合物的气相色谱\|质谱检测方法, 考察了基质效应和分析保护剂在方法中的应用, 评价了3种分析保护剂组合的加入对补偿基质效应的影响, 确定了最佳配比. 样品前处理采用乙腈提取, 用PSA(Primary-secondary amine)固相材料分散净化技术, 用气质联机在选择离子监测模式下分析检测. 该方法在0.01～1.00 mg/L范围内线性关系良好, 相关系数大于0.98, 最低检测浓度除溴氰菊酯和异菌脲外均在0.2～9.4 mg/kg之间, 各化合物添加回收率为81.8%～119.5%, 相对标准偏差为0.8%～17.6%.     

磁性多壁碳纳米管净化技术快速测定甘蓝中10种农药残留

采用磁性多壁碳纳米管-超高效液相色谱-串联质谱技术快速测定甘蓝中的10种农药残留。样品用乙腈提取,稀释后经磁性多壁碳纳米管净化,通过Waters CORTECS C_(18)+色谱柱分离,以甲醇和0.1%的甲酸水溶液为流动相进行梯度洗脱,采用电喷雾-正离子多反应监测模式,基质外标法定量。对磁性多壁碳纳米管的吸附时间和脱附溶剂进行考察。10种农药在相应的浓度范围内线性相关系数均大于0.99,该方法的定量限在0.3~3.0μg/kg之间。在5.0,25.0和50.0μg/kg 3个浓度添加水平下,农药的回收率为80.1%~102.3%,相对标准偏差在1.9%~9.4%之间。磁性多壁碳纳米管具有较好的净化效果,适用于蔬菜中农药多残留的快速检测。     

QuEChERS-超高效液相色谱-串联质谱法测定蔬菜中41种农药残留

采用QuEChERS-超高效液相色谱-串联质谱技术,建立了蔬菜中常见的隐性农药、禁限用农药、植物生长调节剂等检出率较高的41种农药残留的测定方法。蔬菜样品用1%(v/v)乙酸-乙腈溶液提取,乙二胺-N-丙基硅烷(PSA)净化后直接进样分析,采用正、负离子多反应监测(MRM)模式,外标法定量。结果表明,在优化后的QuEChERS、色谱和质谱条件下,41种农药在1.0~100 μg/L范围内线性关系良好,相关系数(r²)大于0.999,检出限为0.003~1.00 μg/kg,不同基质中的平均回收率范围为74.1%~120.4%,相对标准偏差(RSD)范围为2.8%~11.9%。该方法快速简便、灵敏度高、净化效果好,可用于蔬菜中41种农药的快速测定,为蔬菜质量安全风险评估工作提供了有力保障。     

液相色谱-串联质谱法测定蔬菜及其制品中5种农药残留量

提出了液相色谱-串联质谱法测定蔬菜及其制品中苯霜灵、灭多威、扑灭津、哒螨灵及吡螨胺等5种农药残留量的方法。蔬菜样品经含0.1%(体积分数)乙酸的乙腈及无水硫酸镁和无水乙酸钠提取并离心分离后,取上清液蒸干,用乙酸酸化的乙腈2mL溶解。将此溶液加入于PSA、C18与石墨碳黑混合吸附剂粉末中经涡旋混合的分散固相净化方法净化。以Hypersil GOLD-C18色谱柱为分离柱,以不同体积比的(A)甲醇和(B)甲酸-水(1+9)的混合液为流动相进行梯度洗脱,洗脱液用乙腈-水(2+8)混合液定容,进行MS测定。采用电喷雾负离子源多反应监测模式检测。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)均为0.01mg·kg-1。加标回收率在86.1%~95.7%之间,测定值的相对标准偏差(n=6)在1.2%~3.8%之间。     

水果蔬菜中多种杀菌剂的基质固相分散液相色谱测定方法研究

采用基质固相分散(MSPD)代替液液分配和固相萃取,从蔬菜水果中提取、净化10种常用杀菌剂农药残留,用C18硅胶交联剂作为固相吸附剂,乙酸乙酯作为洗脱液,用HPLC/PDA和LC-MS进行分析检测。10种杀菌剂在0.5~5 mg/kg含量的添加回收率在65%~110%之间,相对标准偏差小于10%,使用HPLC、PDA和LC-MS的检出限分别在0.02~0.2 mg/kg和0.002~0.01 mg/kg之间。该方法节省溶剂,提取和净化一步完成,适用于新鲜水果和蔬菜中10种杀菌剂的残留分析。     

超高效液相色谱-串联质谱法测定蔬菜和水果中腈吡螨酯残留量

建立了蔬菜和水果中腈吡螨酯残留量的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。样品经乙腈均质提取,混合使用乙二胺-N-丙基硅烷(PSA)和C18两种基质分散净化剂净化,净化液过膜后直接进行UPLC-MS/MS检测。通过考察腈吡螨酯在不同果蔬样品中的基质效应发现,采用UPLC-MS/MS检测蔬菜和水果中腈吡螨酯残留量时,腈吡螨酯在不同种类样品中存在不同程度的基质减弱效应,采用空白基质溶液稀释标准建立校正的标准曲线外标法定量以消除基质效应。结果表明,腈吡螨酯在0.05~10μg/L浓度范围内具有良好的线性关系,相关系数不低于0.999 6。在0.000 05~2 mg/kg范围内进行加标回收率实验,平均回收率为81.1%~99.3%,相对标准偏差为4.7%~9.3%,方法的定量下限为0.043μg/kg,检出限为0.013μg/kg。     

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.