河豚鱼、鳗鱼和烤鳗中角黄素残留的超高效液相色谱法测定和超高效液相色谱-串联质谱法确证

建立了河豚鱼、鳗鱼和烤鳗中角黄素残留的超高效液相色谱测定方法和超高效液相色谱-串联质谱确证方法。样品用抗氧化剂焦性没食子酸保护,乙腈均质提取,正己烷液-液分配净化,超高效液相色谱-紫外检测器测定,外标法定量,超高效液相色谱-串联质谱法确证。测定方法采用BEHC18色谱柱(50 mm×2.1 mm,i.d.1.7μm),流动相为V(0.1%的甲酸)∶V(乙腈)=3∶97,检测波长470 nm。实验结果表明,角黄素在0.05~2.0 mg/L范围内线性关系良好(r=0.9999),在空白样品中,添加低、中、高3个浓度水平(0.05,0.1,1.0 mg/kg),角黄素的回收率均在82.52%~96.96%之间,相对标准偏差为6.9%~15%。方法的检出限(LOD)为0.02 mg/kg,定量限(LOQ)为0.05 mg/kg。串联质谱确证方法采用电喷雾(ESI)离子源,在正离子模式下以多反应监测(MRM)扫描方式检测,定性离子对565.5/203.2和565.5/133.1,定量离子对565.5/203.2。     

超高效液相色谱-电喷雾串联质谱法同时测定大豆中107种除草剂残留

采用超高效液相色谱-电喷雾串联四极杆质谱仪(UPLC-ESI-MS-MS),在多反应监测(MRM)模式下建立了测定大豆中107种除草剂残留的定性定量分析方法。方法中的除草剂,覆盖了日本"肯定列表"中规定的大部分除草剂。样品分别用乙腈和V(乙腈)∶V(50mmol/LHCl)=7∶3混合液各提取一次,合并提取液,并与N-丙基乙二胺(PSA)混合去除色素,然后通过冷冻离心去除脂肪,再经过500mgC18小柱进一步净化,得到样品溶液。使用ACQuityUPLCTMBEHC18反相柱,流动相为0.2%甲酸溶液和乙腈,在梯度条件下分析;目标分析物使用超高效液相色谱-电喷雾串联质谱进行测定;以保留时间和离子对(母离子和一个碎片离子)信息比较进行定性和定量。该法的定量限为0.1～50μg/kg。添加水平在0.05～2μg/kg范围内,多数除草剂的加标回收率为58%～130%,相对标准偏差为4.3%～23%。本方法简便、有效、灵敏。适合大豆中残留的多种除草剂筛查检测的需要。     

凝胶渗透色谱-高效液相色谱-串联质谱法同时测定烟草中3种抑芽剂残留

建立了用凝胶渗透色谱净化-液相色谱-串联质谱分析烟草中3种抑芽剂残留的方法。卷烟中的待测抑芽剂组分用V(乙酸乙酯)∶V(环己烷)=1∶1超声提取后通过凝胶渗透色谱净化;凝胶色谱柱为Biobeads S-X3玻璃柱(50 g,400 mm×25 mm),流动相为V(乙酸乙酯)∶V(环己烷)=1∶1溶液,流速5 mL/min;收集第10~25 min流出的液体用液相色谱色谱-三重四极杆串联质谱仪测定。在0.5~100 ng/mL的质量浓度范围内,各种抑芽剂标准溶液的线性相关系数均大于0.99。在样品中添加3种抑芽剂(添加水平为5,20,100μg/kg)的混合标准溶液,平均回收率在86.2%~108.4%之间,3种抑芽剂的RSD在1.1%~7.5%之间;方法的检测限在0.01~0.06μg/kg之间。     

动物肌肉组织中己烯雌酚残留量的液相色谱-串联质谱法测定

建立了动物肌肉组织中己烯雌酚残留的液相色谱-串联质谱分析方法。样品用乙腈-甲酸溶液均质提取,以乙腈-水(体积比85∶15)为流动相经反相色谱柱分离后,采用多反应监测(MRM)负离子模式检测,定性离子对为m/z266.9/237.0和266.9/251.0;其中m/z266.9/251.0用于外标法定量。空白样品及其加标实验结果表明,特征离子相对强度比值稳定,无基质干扰,结合保留时间可实现准确的定性定量,方法检出限为0.10μg/kg(S/N=3),不同肌肉基质样本添加水平在0.5~5.0μg/kg时,平均回收率为82%~96%,相对标准偏差(n=6)为3.7%~6.4%。     

离子交换色谱-荧光检测法测定化妆品中苯海拉明及串联质谱确证

建立了化妆品中苯海拉明的离子交换色谱-荧光检测方法及液相色谱-串联质谱确证方法。样品用含0.2%甲酸的乙腈提取,定量检测时以乙腈-0.05 mol/L KH2PO4溶液(7+3,V/V)为流动相,强阳离子交换色谱柱(250×4.6 mm,5μm)分离,荧光检测激发波长258 nm,发射波长288 nm,外标法定量,苯海拉明检出限为1.5 mg/kg,在0.2~20 mg/L范围内线性关系良好,相关系数为0.9999,方法的回收率在87.6%~106.3%范围内,相对标准偏差低于6.3%。质谱确证时用BEH C18色谱柱分离,乙腈-0.2%甲酸系统梯度洗脱,采用质谱碎片和相对离子丰度进行定性确认。     

超高效液相色谱-质谱法快速分析番茄及其制品中矮壮素和缩节胺残留量

采用超高效液相色谱-串联质谱(UPLC/MS-MS)研究了番茄及其制品中矮壮素和缩节胺残留量的测定方法。样品用水提取,无需经过任何净化过程;在粒径为1.7μm的超高压亲水作用色谱柱上以V(乙腈)∶V(含0.1%甲酸的10 mmol/L乙酸铵溶液)=6∶4为流动相,等度洗脱分离;电喷雾正离子检测(ESI ),多反应监测模式(MRM)对定性和定量离子进行MS测定。结果表明:矮壮素和缩节胺的添加水平在5、10和20μg/kg时,回收率范围分别为78.5%~90.1%和80.0%~104.0%;相对标准偏差在9.5%~11.3%和10.5%~13.2%之间;方法检出限均为0.8μg/kg。本方法仅需约2 m in的检测时间,且灵敏、准确,完全满足番茄及其制品中矮壮素和缩节胺残留量的快速、高灵敏度的分析要求。     

分散固相萃取-液相色谱-串联质谱法测定水果中19种酸性农药

建立了同时检测葡萄、苹果和桔子等水果中2,4-滴等19种酸性农药的分散固相萃取-液相色谱-串联质谱(HPLC-MS/MS)方法。葡萄、苹果和桔子样品经乙酸-乙腈(1∶99,V/V)提取后,C18分散固相萃取净化,采用反相C18色谱柱分离。以0.1%甲酸和0.1%甲酸-乙腈溶液作为流动相进行梯度洗脱,采用多反应监测离子模式进行定性分析,基质标准曲线外标法进行定量分析,线性范围在0.01~0.2 mg/kg之间。在0.02,0.05和0.1 mg/kg添加水平下,19种酸性农药的回收率为70.3%～105.3%;相对标准偏差为0.37%～10.9%。本方法的定量限为0.005～0.02 mg/kg。     

液相色谱-串联质谱法测定液态乳制品中的苯代三聚氰胺

建立了液态乳制品中苯代三聚氰胺的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。优化了前处理条件、液相色谱和质谱参数。样品经LC-C18固相萃取柱富集净化后,采用ZORBAX-Eclipse Plus C18色谱柱分离,流动相为乙腈-水(15∶85,体积比),流速为0.3 mL/min。采用正离子模式的电喷雾质谱检测,多反应(MRM)选择离子监测,定量离子与定性离子分别为m/z 104.1与m/z 146.0,外标法定量。结果表明,苯代三聚氰胺在2~100 μg/L范围内线性关系良好,相关系数为0.999 1,方法的检出限和定量下限分别为1.0 μg/kg和3.0 μg/kg。在低、中、高3个加标水平下的平均回收率为77%~105%,相对标准偏差(RSD)为2.3%~5.0%。该方法操作简单、准确可靠,适用于液态乳制品中苯代三聚氰胺的测定。     

液相色谱-电喷雾离子阱质谱对芥子碱的测定方法

探讨了采用液相色谱-电喷雾串联质谱法检测小鼠前列腺中芥子碱硫氰酸盐的方法。流动相为V(乙腈)∶V(0.5%乙酸)=20∶80,色谱柱为ZorbaxXDB-C18(150 mm×4.6 mmi.d.,5μm),流速为0.6 mL/min。芥子碱硫氰酸盐的准分子离子和二级碎片离子分别为m/z 304和m/z 251,方法的检出限为0.7μg/L,线性范围为2.7~80.5μg/L,r为0.9934,相对标准偏差为7.5%~12.9%,样品的回收率为81.2%~102.5%。     

液相色谱-串联质谱法测定液态乳制品中的苯代三聚氰胺

建立了液态乳制品中苯代三聚氰胺的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。优化了前处理条件、液相色谱和质谱参数。样品经LC-C18固相萃取柱富集净化后,采用ZORBAX Eclipse Plus C18色谱柱分离,流动相为乙腈-水(15∶85,体积比),流速为0.3 mL/min。采用正离子模式的电喷雾质谱检测,多反应(MRM)选择离子监测,定量离子与定性离子分别为m/z 104.1与m/z 146.0,外标法定量。结果表明,苯代三聚氰胺在2~100μg/L范围内线性关系良好,相关系数为0.999 1,方法的检出限和定量下限分别为1.0μg/kg和3.0μg/kg。在低、中、高3个加标水平下的平均回收率为77%~105%,相对标准偏差(RSD)为2.3%~5.0%。该方法操作简单、准确可靠,适用于液态乳制品中苯代三聚氰胺的测定。     

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.