苹果中多菌灵、噻菌灵和甲基托布津的高效液相色谱法分析

建立了同时检测苹果中多菌灵、噻菌灵和甲基托布津残留量的高效液相色谱(HPLC)分析方法.样品经乙酸乙酯提取,旋转蒸发仪浓缩,氮气吹干甲醇定容后,采用配有二极管阵列检测器(DAD)的HPLC测定,外标法定量.在添加不同浓度的标准品时,多菌灵、噻菌灵和甲基托布津的添加回收率分别为87.7%～118.7%、72.8%～80.3%、64.0%～66.8%.方法对多菌灵、噻菌灵和甲基托布津3种农药的检出限较低,分别为0.134、0.230和0.250mg/L,可以满足苹果汁中多菌灵、噻菌灵和甲基托布津的残留限量检测要求.检测果皮样品中的农药残留量,多菌灵的残留量为7.24×10-2mg/kg,噻菌灵和甲基托布津未检出,低于国标中规定的残留限量标准.     

高效液相色谱法测定水果和蔬菜中残留的多菌灵、吡虫啉和甲基托布津

建立了一个溶剂萃取后高效液相色谱法测定水果和蔬菜中残留农药多茵灵、吡虫啉和甲基托布津的方法.样品中残留农药用二氯甲烷与冰乙酸混合溶剂萃取,然后在AtlantisB> dC18>色谱柱上分离,用甲醇及0.1 mol·L-1盐酸的混合溶液作梯度淋洗,洗出液中的农药在267 nm波长处紫外检测.方法对多茵灵、吡虫啉和甲基托布津的回收率分别为84%,83%,89%;相对偏差分别为10.68%,6.60%,9.08%.     

高效液相色谱法对环境样品中甲基托布津与甲霜灵残留的测定

建立了自动固相萃取/高效液相色谱法测定地表水和土壤中甲基托布津和甲霜灵残留的方法。地表水采用C18固相萃取小柱进行富集、净化及浓缩;土壤采用丙酮-二氯甲烷(体积比3∶7)溶液振荡萃取,弗罗里硅土小柱净化和浓缩;以乙腈和水为流动相,于230 nm波长处对样品进行高效液相色谱检测。甲基托布津和甲霜灵在水中的检出限分别为0.36、3.49μg/L,在土壤中的检出限分别为0.03、0.18 mg/kg;在优化实验条件下,甲基托布津和甲霜灵在水样和土壤样品中的添加回收率为77%~105%,精密度为1.2%~8.5%。方法可用于环境样品中甲霜灵和甲基托布津残留量的测定。     

液相色谱-质谱法同时测定甜瓜样品中的噻菌灵、甲基托布津、扑海因

采用液相色谱-质谱法同时测定甜瓜样品中的噻菌灵、甲基托布津和扑海因含量。离子化技术采用大气压电喷雾( )方式,定量测定使用选择离子监测模式。检测离子m／x：202．25、343．28、331．07。检出限：噻菌灵为0．1pg,甲基托布津为10．2pg,扑海因为2．42ng;回收率为81．0％～110％;相对标准偏差为1．5％～16．8％。方法灵敏度高,选择性好,准确度高,用于甜瓜样品中噻菌灵、甲基托布津、扑海因的测定,获得了满意的结果。     

高效液相色谱法同时测定甲基托布津和扑海因

提出了一种同时测定甲基托布津和扑海因的高效液相色谱法,方法的线性范围,相对标准偏差和检测限分别为：甲基托布津：1．0－40.0mg/L,0．7％,1．0mg/L,扎海因：0．25－125．0mg/L.0.6%,0.25mg/L,本方法用于保鲜剂中扑海因和甲基托布津含量及甜瓜中残留量的测定,取得了很好的结果。     

液相色谱-串联质谱分析组织中基因组脱氧核糖核酸羟甲基胞嘧啶水平

5-羟甲基胞嘧啶通过阻止脱氧核糖核酸(DNA)甲基化转移酶1(DMNT1)甲基化胞嘧啶来影响DNA甲基化的程度。本文建立了液相色谱-串联质谱(LC-MS/MS)测定组织中全基因组5-羟甲基胞嘧啶水平的方法。采用苯酚-氯仿提取组织DNA,提取的DNA用88%甲酸在140 ℃下裂解,DNA裂解液加入同位素胞嘧啶作内标,经N2吹干后,加乙腈-水(9:1, v/v)溶解,用LC-MS/MS检测5-羟甲基胞嘧啶的含量,并计算全基因组中5-羟甲基胞嘧啶的水平。结果表明,5-羟甲基胞嘧啶的线性范围为0.1～30 ng/mL,相关系数为0.9969,检出限(信噪比为3计)和定量限(信噪比为10计)分别为0.057 ng/mL和0.090 ng/mL;日内相对标准偏差和日间相对标准偏差分别为5.13%和6.24%;加标回收率为90.24%～97.53%。用该方法检测了大鼠大脑组织DNA羟甲基化水平,平均结果为0.66%。该方法简便,重现性好,灵敏度较高,能满足全基因组5-羟甲基胞嘧啶定量检测的要求。     

高效液相色谱法测定咪唑生产工艺中反应液中咪唑及2种杂质2-甲基咪唑和4-甲基咪唑

建立了高效液相色谱(HPLC)外标定量分析咪唑生产工艺中反应液中咪唑及杂质2-甲基咪唑和4-甲基咪唑含量的方法。在色谱分析中,选用Supersil-ODS-B色谱柱为固定相;选用体积比为40∶60的乙腈-离子对试剂(溶液pH为3.5,内含16 mmol·L~(-1)十二烷基硫酸钠和17mmol·L~(-1)磷酸二氢钾)溶液为流动相进行等度洗脱;采用二极管阵列检测器进行检测,检测波长为210nm。结果显示:咪唑、2-甲基咪唑及4-甲基咪唑标准曲线的线性范围均为10～100mg·L~(-1),检出限(3S/N)分别为0.02,0.02,0.03mg·L~(-1)。咪唑在20mg·L~(-1)和100mg·L~(-1)添加水平下的平均加标回收率分别为100%,99.2%,相对标准偏差(n=8)为0.27%。用本方法对同一批反应液不同反应阶段的9个样品中咪唑进行了测定,测定值为10.11%～10.71%;杂质2-甲基咪唑有检出,但低于测定下限;杂质4-甲基咪唑未检出。与气相色谱法进行了比对,两者测定结果基本一致。试验结果表明,该方法准确度好、灵敏度高、重现性好,能够准确测定咪唑生产工艺中反应液中咪唑、2-甲基咪唑及4-甲基咪唑的含量。     

固相萃取-高效液相色谱法对罗汉果及其提取物中甲基托布津与多菌灵的同时测定

应用固相萃取及高效液相色谱技术,建立了同时测定罗汉果及其提取物中甲基托布津和多菌灵残留的方法。罗汉果及其提取物样品经乙腈超声提取后,由弗罗里硅土固相萃取小柱净化,以Zorbax extend-C18(150 mm×4.6 mm,5μm)色谱柱为分析柱,乙酸铵水溶液(含乙酸0.5%)-甲醇为流动相,线性梯度淋洗,紫外二极管矩阵检测器检测,波长为270 nm。结果表明,甲基托布津和多菌灵在0.5~15.0 mg.L-1范围内有良好的线性关系,方法的定量下限(S/N=10)分别为0.06、0.1 mg.kg-1,加标回收率为77%~96%,相对标准偏差不大于7.1%。     

液相色谱-串联质谱法测定蔬菜和水果中硝苯菌酯的残留量

建立了一种通过检测硝苯菌酯(2,4-dinitro-6-(1-methylheptyl) phenyl crotonate, 2,4-DNOPC)相应的水解产物2,4-二硝基-6-(1-甲基庚基)苯酚(2,4-dinitro-6-(1-methylheptyl) phenol, 2,4-DNOP)来测定蔬菜和水果中2,4-DNOPC残留量的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)检测方法。蔬菜和水果样品用丙酮-甲醇-盐酸的混合液进行液-液分配提取,在碱性条件下超声水解后再进行液-液分配提取,然后进行LC-MS/MS测定。2,4-DNOPC在6种蔬菜和水果中的回收率试验结果表明,2,4-DNOPC在甘蓝中的添加回收率为89.7%～93.3%,相对标准偏差(RSD)为6.3%～8.5%;在黄瓜中的添加回收率为87.7%～95.1%, RSD为5.8%～10.4%;在番茄中的添加回收率为89.3%～96.0%, RSD为6.8%～9.2%;在苹果中的添加回收率为92.0%～98.3%, RSD为5.1%～10.3%;在梨中的添加回收率为89.0%～95.0%, RSD为5.3%～10.2%;在葡萄中的添加回收率为81.2%～95.8%, RSD为5.8%～10.4%。2,4-DNOPC在6种蔬菜和水果的最低检测浓度均为0.01 mg/kg。该检测方法样品前处理简单、快速,分析时间短,灵敏度、准确度和精密度均符合农药残留检测要求,适用于蔬菜和水果中硝苯菌酯残留量的检测。     

气相色谱–质谱法测定食品接触材料聚苯醚中2,6-二甲基苯酚的迁移量

建立食品接触材料聚苯醚中2,6-二甲基苯酚迁移量的气相色谱–质谱检测方法。将聚苯醚样品加至食品模拟液中,于60℃下迁移2 h,再用乙酸乙酯提取。进样口温度为180℃,初始温度为80℃,保持2 min,以20℃/min升温至200℃,保持2 min,再升温至240℃,经DB–WAX气相色谱柱(30 m×0.25 mm,0.25μm)分离,质谱法测定,以保留时间定性,外标法定量。2,6-二甲基苯酚的质量浓度在0.01～0.5 mg/L范围内与色谱峰面积呈良好的线性关系,线性相关系数为0.999 9,方法检出限为0.01 mg/L。用4%乙酸、10%乙醇、95%乙醇和异辛烷分别进行加标回收试验,方法的回收率为91.7%～104.5%,测定结果的相对标准偏差为1.11%～4.63%(n=6)。该方法为检测食品接触材料中2,6-二甲基苯酚迁移含量测定提供了准确、可靠的方法。     

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.