固相萃取-液相色谱-质谱法测定益母草中7种真菌毒素

建立液相色谱-质谱法测定益母草中黄曲霉毒素G2、G1、B2、B1、T-2毒素、赭曲霉毒素A、展青霉素7种真菌毒素的方法。样品经过70%甲醇溶液超声提取,用水稀释后用固相萃取柱富集净化,以C18色谱柱分离,多反应监测(MRM)模式进行检测,7种真菌毒素得到快速分离。7种真菌毒素的质量浓度与色谱峰面积成良好的线性关系,线性相关系数在0.9972~0.9992之间,检出限为0.047~4.724μg/kg。平均加标回收率为72.8%~95.5%,测定结果的相对标准偏差为3.1%~5.7%(n=6)。该检测方法可同时高效准确检测益母草中7种真菌毒素的含量,可用于赭曲霉毒素A的定量风险评估,为益母草的安全评价提供了科学依据。     

SiO2@松香基高分子(Ru131)色谱柱分离测定岩黄连中脱氢卡维丁、盐酸巴马汀和盐酸小檗碱

建立测定岩黄连中脱氢卡维丁、盐酸巴马汀、盐酸小檗碱含量的液相色谱分析方法.确定了脱氢卡维丁、盐酸巴马汀和盐酸小檗碱的色谱分离条件为:SiO2@松香基高分子(Ru131)色谱柱(250 mm×4.6mm,5μm),以乙腈-0.0050 mol·L-1磷酸盐缓冲溶液(pH=3.0)=20∶80(V/V)为流动相,紫外检测波...     

毛细管电泳-电化学检测益母草及其冲剂中的黄酮类化合物

用毛细管电泳-电化学检测(CE-ED)法同时测定了益母草及三种益母草冲剂中的根皮苷、橙皮素、芦丁、山奈酚、洋芹素和槲皮素六种黄酮类化合物的含量。考察了实验参数对分离、检测的影响,得到了最佳试验条件。采用300μm碳圆盘电极为工作电极,检测电位为 0.95 V(vs.SCE),在80 mmol/L的Na2B4O7-H3BO3(pH 8.7)的运行缓冲液中,上述各组分在20 min内能完全分离。根皮苷、橙皮素、芦丁、山奈酚、洋芹素、槲皮素在5.00×10-7~1.00×10-4g/mL范围内均与其相应的峰电流呈线性关系,其检出限(S/N=3)分别为4.68×10-7、2.03×10-7、4.68×10-7、2.68×10-7、4.81×10-7、3.61×10-7g/mL。该法应用于实际样品的分析,结果令人满意。     

益母草碱类似物设计、合成及其Na+/H+交换器-1抑制活性

以中药益母草中有效成分益母草碱为先导化合物,按生物电子等排原理,设计合成了18个益母草碱类似物.通过MS,1H NMR,13C NMR对化合物结构进行表征.初步的药效研究结果表明部分化合物具有Na+/H+交换器-1 (NHE-1)抑制活性,其中化合物1a和1e的活性显著强于阳性对照药Cariporide.     

HPLC法同时测定石蒜中加兰他敏和石蒜碱

建立了高效液相色谱同时测定石蒜中加兰他敏和石蒜碱含量的方法。 采用phenomenex-C18色谱柱,以乙腈(A)-0.1%TFA水溶液(B)为流动相梯度洗脱,检测波长289 nm。 结果表明,加兰他敏和石蒜碱均在0.5～10 mg/L(r=0.9999)呈现良好的线性关系,最低检测限(S/N=3)分别为0.09和0.15 mg/L,平均加样回收率分别为99.53%和96.82%。 该方法简单、快速、准确,适合于石蒜中加兰他敏和石蒜碱的测定。     

高效液相色谱法测定纺织品中1-甲基-2-吡咯烷酮的含量

建立了纺织品中1-甲基-2-吡咯烷酮(N-Methylpyrrolidone,NMP)的高效液相色谱检测方法。样品经超声提取,采用ZORBAX SB-C18色谱柱分离,流动相为乙腈-水(30/70,V/V),检测波长210nm。结果表明,在0.4~48mg/L范围内,NMP的响应峰面积与其质量浓度呈良好的线性关系,相关系数r=0.9997,检测限(S/N=3)为0.2mg/kg,定量限(S/N=10)为0.4mg/kg,平均回收率为80.6%~108.6%。方法具有较高的灵敏度,可简便、快速地测定纺织品中NMP的含量。     

高效液相色谱法分析元宝枫叶中儿茶素类物质

本文建立了元宝枫树叶中儿茶素种类及其含量的高效液相色谱(HPLC)测定方法。采用反相C18色谱柱,以甲醇/水(含0.5%乙酸)=25/75(V/V)为流动相,对没食子儿茶素(GC)、表没食子儿茶素(EGC)、儿茶素(C)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素(EC)和没食子儿茶素没食子酸酯(GCG)进行定性、定量分析;以甲醇/水(含0.5%乙酸)=35/65(V/V)为流动相,对表儿茶素没食子酸酯(ECG)和儿茶素没食子酸酯(CG)进行定性分析,柱温均为35℃,检测波长为278 nm,流速为1.0mL/min。结果表明:元宝枫叶中有EGC、EC和GCG,其它五种则无。EGC平均含量为0.0389 mg/g,方法精密度(RSD)为0.42%(n=6);EC平均含量为0.0289 mg/g,方法RSD为1.5%(n=6);GCG平均含量为0.284 mg/g,方法RSD为0.32%(n=6)。该方法简便、准确、分离效果好,为元宝枫叶开发成茶叶、饮料以及医疗保健品提供重要依据。     

液相色谱-电喷雾质谱联用测定细辛及养血清脑颗粒中马兜铃酸A

建立了反相液相色谱-电喷雾-三级四极杆质谱联用测定细辛及其制剂养血清脑颗粒中的马兜铃酸A含量的方法。本方法采用C18色谱柱,以甲醇和0.1%的甲酸水溶液(V/V)系统为流动相,选择性地测定m/z340.0>223.0的跃迁,在20~800μg/L范围内线性良好(r=0.9991);检出限为35 pg;精密度(RSD)为4.8%和回收率为98.1%,均较好,本方法准确、快速、简便,可用于马兜铃酸A的限量测定。     

可逆性化学反应结合HPLC测定氨丙基硅胶表面上氨基的含量

采用苯甲醛与氨丙基硅胶表面上的氨基反应形成希夫碱,再将其水解为苯甲醛,通过HPLC测定水解后苯甲醛的量,可以间接测定硅胶表面上所链接的氨基量,从而建立了一种测定氨丙基硅胶表面上氨基含量的方法.希夫碱的生成与水解最佳条件分别为:40℃反应1 h;40℃,pH 6.0超声反应1 h;色谱条件:PHENOMENEX Luna C18(150 mm×4.6mm,5μm)色谱柱,流动相:V(乙腈):V(水)=50:50,柱温30℃,紫外检测波长246 nm,流速1.0 mL/min.苯甲醛的线性范围为1.0～50.0 mg/L(r=0.9999),平均回收率100.8%,RDS为1.6%.该方法对氨丙基硅胶没有破坏性,测定完后的硅胶可回收使用,适用于氨丙基硅胶表面上氨基的含量测定.     

嗜碱微生物细胞内氨基酸的高效液相色谱测定及代谢途径分析

建立了嗜碱微生物细胞内17种氨基酸的高效液相色谱分析方法。采用Sinochrom ODS-BP色谱柱,以乙腈∶水=1∶1(溶液A),0.06mol/L乙酸钠溶液 0.1%N,N-二甲基甲酰胺 10%乙腈,用5%醋酸溶液调至pH=6.4(溶液B)为流动相进行梯度洗脱,流速0.8mL/min,柱温35°C,检测波长360nm。在此色谱条件下,各组分在32min内均得到较好分离,回收率符合含量测定要求。运用本方法测定嗜碱微生物发酵不同时间细胞内氨基酸含量,得到嗜碱微生物细胞内氨基酸在发酵过程中的变化趋势,分析了相关代谢途径。     

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.