反相高效液相法测定枳实、枳壳中橙皮甙和柚皮甙的含量

 采用高效液相法测定了枳实和枳壳中的橙皮甙和柚皮甙含量。柱为HypersilODS1柱(250mm×4 6mmi d ),流动相为乙腈 0 5%乙酸溶液(体积比为22∶78),流速为1 0mL/min,检测波长为283nm。柚皮甙和橙皮甙的线性范围分别为0 060g/L～0 604g/L和0 0125g/L～0 125g/L,柚皮甙和橙皮甙的平均回收率分别为97 1%和95 3%。该方法具有操作简便、分析快速、准确等优点。     

苯氨基甲酸酯化β-环糊精手性固定相测定中草药中柚皮甙对映体

采用自制的苯氨基甲酸酯衍生化β-环糊精键合SBA-15手性固定相,以甲醇-水作流动相,拆分了柚皮甙对映体;考察了流动相组成、柱温、检测波长等对柚皮甙拆分和测定的影响,优化的色谱条件为:流动相为甲醇-水(55:45,V/V),流速0.5 m L/min,柱温20℃,进样量10μL,检测波长为285 nm。基于上述条件,对中草药化橘红、香橼、枳壳及柚皮中的柚皮甙对映体进行了含量测定。柚皮甙每个对映异构体均在0.5~500μg/m L范围内线性关系良好(r≥0.995),检出限为0.04μg/m L(S/N=3)。以化橘红为例,柚皮甙第一个对映体的加标平均回收率为93.8%和RSD为1.2%(n=5),第二个对映体的加标平均回收率为91.3%和RSD为1.6%(n=5)。测得化橘红、香橼、枳壳和柚皮中柚皮甙两对映体的含量分别为10.42 mg/g和15.84 mg/g,15.39 mg/g和49.52 mg/g,16.53 mg/g和95.80 mg/g,18.47 mg/g和30.98 mg/g。     

催化动力学极谱法测定痕量甲醛

在稀硫酸介质中,痕量甲醛对溴酸钾氧化甲基红的反应有很强的催化作用.而甲基红及其氧化产物均能在滴汞电极上产生灵敏的极谱吸附波,其峰电位依次为-0.57 V及-0.49 V(vs.SCE).在-0.57 V处测得的甲基红的峰电流的二阶导数值与反应体系中的甲醛浓度在0.2～6.5 mg·L-1之间呈线性关系,方法的检出限为0.041 mg·L-1,对2.5 mg·L-1甲醛测定8次,得出RSD值为1.8%,标准加入法回收率试验的结果在97.0%～104.0%之间.     

高效液相色谱法测定生物体液中γ-氨基丁酸

研究了邻苯二甲醛柱前衍生反相高效液相色谱法测定血浆和脑脊液中γ-氨基丁酸的含量。色谱条件:色谱柱为Nova-pak C18柱,流动相为50 mmol.L-1的乙酸钠(pH 6.8)、甲醇和四氢呋喃(A:82∶17∶1;B:22∶77∶1,V/V),梯度洗脱。方法的线性范围为0.5~100μmol.L-1,检出限为0.04μmol.L-1。日间和日内测定的精密度分别为1.9%~6.8%和1.6%~5.7%;标准加入回收率在92.7%与96.8%之间。采用上述方法测定正常人和癫痫病患者血浆和脑脊液中γ-氨基丁酸含量,结果令人满意。     

离子色谱法测定大气降尘中四种阴离子

以流速 1.5ml·min- 1,0 .2 4mol·L- 1Na2 CO3和 0 .30mol·L- 1NaHCO3混合液为淋洗液 ,在YSA 4型阴离子分离柱上分离 ,采用带电导检测器的离子色谱仪对大气降尘中四种阴离子进行分离测定 ,F- 、Cl- 、NO- 3、SO2 - 4的检出限 (3S/N)分别为 0 .0 0 1,0 .0 0 1,0 .0 0 6 ,0 .0 0 4mg·L- 1,相关系数分别为 0 .9991,0 .9986 ,0 .9997,0 .9984 ,RSD分别为 0 .80 % ,0 .76 % ,1.80 % ,1 90 %。     

微分电位溶出伏安法同时测定甘草中痕量铅和镉

建立了在NH4OAc HOAc介质中,用微分电位溶出伏安法测定中药甘草中痕量铅和镉的方法,利用该法对中药甘草煎煮前后及其煎液中铅和镉的含量进行测定。试验表明,镉和铅分别在-0.66V(vs.SCE)和-0.47V(vs.SCE)电位处形成两个灵敏的二次微分溶出峰;铅在0～0.8mg·L-1,镉在0～0.4mg·L-1范围,峰电流与浓度呈良好的线性关系;铅和镉检出限分别为0.15和0.1μg·L-1,相对标准偏差≤1.39%;铅和镉加标回收率在94%～103%之间。结果表明,该甘草样品中铅和镉含量均低于国家安全标准,甘草煎煮液中铅的浸出率较高,镉的浸出率则较低,方法也适用于其它类似中药。     

抗坏血酸及L-半胱氨酸的流动注射动力学同时测定法

pH2～9时,抗坏血酸与L-半胱氨酸均可与Fe3+-邻菲咯啉混合液反应,生成Fe2+-邻菲咯咻有色配合物,但两者反应速度相差极大。根据这个原理,采用流动注射分析停流技术,建立了抗坏血酸与L-半胱氨酸的动力学吸光光度同时测定法。两者测定的线性范围分别为0～24mg·L-1和0～280mg·L-1,相应的检出限为1mg·L-1和16mg·L-1,抗坏血酸与L-半胱氨酸浓度分别为12.0mg·L-1和160.0mg·L-1时,测定的相对标准偏差分别为0.9％和0.6％,采样频率为30样·h-1。该法灵敏、快速、准确,选择性较高,且流路及设备简单,实用性强,用于实际样品测定,抗坏血酸及L-半胱氨酸的加标回收率分别可达95.2％和92.8％。     

微柱高效液相色谱法测定烟草样品中铁钴镍铜锌锰

研究了用2(2喹啉偶氮)5二甲氨基酚(QADMAP)为柱前衍生试剂,以Waters XterraTMRP18(1.0mm×50mm,2.5μm)微柱为固定相,72%的甲醇(内含0.5%的乙酸)为流动相,高效液相色谱法分离,二极管矩阵检测器检测测定铁、钴、镍、铜、锌和锰的方法。根据信噪比(S/N=3)得各金属离子的检出限分别为:铁3μg·L-1、钴和铜4μg·L-1、镍2μg·L-1、锌5μg·L-1、锰8μg·L-1,方法用于烟草中痕量铁、钴、镍、铜、锌和锰的测定,相对标准偏差在1.6%～3.8%之间,回收率在93%～107%之间,结果满意。     

高效液相色谱法测定汽车尾气催化剂中铂、钯和铑的研究

研究了用 2 羟基萘 1 亚甲基若丹宁(HNPRN) 为柱前衍生试剂,以 Zorbax StableBound (4.6 mm×50 mm, 1.8μm) 快速分离柱为固定相,62%的甲醇(内含0.5%的乙酸)为流动相,高效液相色谱分离,二极管矩阵检测器检测测定铂、钯和铑的方法,三种贵金属元素的络合物在2.0 min内可达到基线分离。根据信噪比(S/N=3)得各金属离子的检出限分别为:铂 1.0μg·L-1,钯0.6μg·L-1,铑0.8μg·L-1,方法用于汽车尾气催化剂中痕量铂、钯和铑的测定,相对标准偏差在1.4%~1.6%之间,结果满意。     

高效液相色谱法测定酶转化液中D-苯丙氨酸

采用HPLC法测定了酶转化液中的D_苯丙氨酸、N_氨甲酰_D_苯丙氨酸和苄基海因。流动相为乙腈-20mmol·L-1 磷酸二氢钾(体积比25∶75), 用磷酸调pH为5.0, 利用DAD检测器, 检测波长为202 nm, 流速为1.0mL·min-1。用外标法进行定量分析, 三者的线性范围分别是1.82~466 mg·L-1(r=0.999)、2.01~516 mg·L-1(r=0.999)、1.94~496 mg·L-1(r=0.999), 回收率为99.9%~100.1%、99.8%~100.0%、99.5%~ 100.4%,RSD(n=6)分别为1.8%、1.6%、1.0%, 检出限为18.7、2.41、64.6 pg。实验结果表明该法简便、快速、结果可靠。     

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.