抑制电导离子色谱法测定蔬菜、药品和水中对氨基苯磺酸

建立抑制电导离子色谱法测定蔬菜、药品和水中对氨基苯磺酸.以SH–AC–3型阴离子交换柱为分离柱,5.0 mmol/L Na2CO3–1.5 mmol/L NaHCO3为淋洗液,以1.0 mL/min的流量等度洗脱,对氨基苯磺酸与常见阴离子可实现完全分离,对氨基苯磺酸的色谱峰面积与质量浓度在0.05～100.0 mg/L范围内线性关系良好,相关系数为0.9999.该方法应用于蒜苗、复方磺胺甲噁唑片、对氨基苯磺酰胺及水中对氨基苯磺酸的测定,样品加标回收率为95.0％～98.4％,5次平行测定值的相对标准偏差为0.92％～3.23％.按3倍信噪比计算对氨基苯磺酸的检出限为0.04 mg/L.该方法选择性好,操作简便.     

活性炭固相萃取/胶束电动色谱联用技术用于雷公藤3种有效成分的测定

建立了活性炭固相萃取/胶束电动色谱法同时测定中药雷公藤中的雷公藤甲素、雷公藤内酯酮和雷酚内酯的方法。优化了萃取p H值、乙醇洗脱体积、电泳运行缓冲溶液p H值与浓度、胶束SDS的浓度及进样时间、电压等条件。进行电泳分离之前,分析物用活性炭进行吸附后用2.0 m L乙醇洗脱。在214 nm波长处,分离电压20 k V,20 mmol/L硼酸-10 mmol/L硼砂(p H 8.0)-20 mmol/L SDS运行缓冲溶液条件下,3种成分在8 min内得到完全分离,雷公藤甲素、雷公藤内酯酮在4.0×10-5~4.0×10-3mol/L,雷酚内酯在4.0×10-5~1.0×10-3mol/L浓度范围内线性关系良好,其回收率为81.0%~102.9%,方法的检出限分别为1.42×10-6,7.90×10-7,2.96×10-7mol/L,相对标准偏差(RSD)分别为3.2%,5.4%,3.5%。所建立的方法简单、快速、准确,成功用于雷公藤片样品的测定。     

托吡卡胺对映体的毛细管电泳-方波安培分离检测

采用毛细管电泳-方波安培检测法,在熔融石英毛细管(75 μm i.d.×50 cm)中,以7 mmol/L 三羟甲基氨基甲烷(Tris)-10 mmol/L柠檬酸-2 mmol/L硼酸-15mmol/L β-环糊精 （β-CD） (pH 3.0)为电泳介质,采用重力进样,高度差为20 cm,进样时间为10 s,在分离电压为15 kV,方波平衡电位+0.8 V的条件下,实现了托吡卡胺对映体的分离检测。线性范围为5~750 μmol/L,检出限为2 μmol/L。对影响分离度的因素β-CD浓度、硼酸浓度及p     

毛细管区带电泳法对柱前衍生胆汁酸的高效分离研究

以7-氨基-1,3-萘二磺酸作为柱前衍生试剂,采用毛细管区带电泳-光二极管阵列检测器分离测定6种胆汁酸。实验综合考察了缓冲溶液浓度、pH值、温度及添加剂对胆汁酸衍生化产物分离效果的影响。在不加其它添加剂情况下,于25mmol/L的pH为9.5的硼酸盐缓冲溶液中,20℃,5kPa压力下进样,进样时间8s,13min可实现6种胆汁酸的快速高效基线分离。该方法检出限(3σ)为0.022～0.046μmol/L,线性范围为0.07～5μmol/L。     

聚对氨基苯磺酸修饰电极测定尿酸

利用循环伏安法制备了聚对氨基苯磺酸修饰电极, 研究了尿酸在该修饰电极上的电化学行为. 结果表明, 该电极对尿酸有较强的电催化作用, 并对抗坏血酸有较强的抗干扰能力. 在pH 5.6的乙酸盐缓冲溶液中, 用循环伏安法和差分脉冲伏安法在该电极上测定了尿酸, 其线性范围分别为1.0×10-5～2.0×10-4 mol/L和4.0×10-7～1.0×10-5 mol/L, 检出限分别为6.0×10-6 mol/L和1.0×10-7 mol/L. 已用于尿液中尿酸的测定.     

聚对氨基苯磺酸/石墨烯复合修饰电极对尿酸的选择性灵敏测定

采用电聚合方法在石墨烯纳米片(GN)的表面聚合一层聚对氨基苯磺酸(PABSA),制备了聚对氨基苯磺酸/石墨烯复合修饰玻碳电极(PABSA/GN/GCE)。研究了尿酸(UA)和抗坏血酸(AA)在该修饰电极上的电化学行为。与聚对氨基苯磺酸修饰电极(PABSA/GCE)及石墨烯单层膜修饰电极(GN/GCE)相比,复合修饰电极PABSA/GN/GCE显著提高了对UA和AA的检测灵敏度和分离度。在0.1 mol/L磷酸盐缓冲溶液(pH7.0)中,UA和AA的峰电位差达344 mV,表明PABSA/GN/GCE能实现对UA的选择性测定。UA的峰电流与其浓度呈良好的线性关系,线性范围为1.0×10-7～8.0×10-4mol/L,检出限为4.5×10-8mol/L。该复合修饰电极用于尿样中尿酸的测定,结果满意。     

聚对氨基苯磺酸修饰玻碳电极不可逆双安培法测定酪氨酸

在玻碳电极上成功地制备了聚对氨基苯磺酸修饰电极(P-p-ABSA/GCE),研究了酪氨酸在该修饰电极上的电化学行为.将此修饰电极用于流动注射不可逆双安培体系的构建,建立了流动注射双安培法直接测定酪氨酸的方法.在0 V外加电压下,在0.005 mol/L硫酸载液中,酪氨酸的氧化峰峰电流与其浓度在2.0×10-6 ～2.0×10-4 mol/L范围内呈良好的线性关系,方法的检出限(S/N=3)为1.0×10-7 mol/L.连续测定1.00×10-5 mol/L的酪氨酸标准溶液,电流值的相对标准偏差(RSD)为1.48%(n=20).该方法具有较高的选择性和灵敏度,应用于测定复方氨基酸注射液中酪氨酸的含量的测定,结果比较满意.     

离子液体对胶束电动色谱胶束微结构以及分离效果的影响

考察了离子液体对胶束电动色谱胶柬微结构以及分离效果的影响.研究结果表明,离子液体使胶束的表面电荷密度变小、粒径变大及其内核极性增大.以泼尼松、氢化可的松和泼尼松龙为分析对象,氢化可的松与泼尼松龙在十二烷基硫酸钠(SDS)胶束体系中不能实现分离.而在SDS-离子液体混合介质(20 mmol/L SDS-10 mmol/L...     

利用偶联反应光度法测定羟胺体系的研究及其应用

利用羟胺与碘反应生成亚硝酸,然后与对氨基苯磺酸发生重氮化反应,再与α-萘胺偶联形成偶氮化合物,从而建立了测定羟胺的新光度法.方法线性范围为2.0×10-6～1.5×10-5 mol/L,表观摩尔吸光系数为3.1×104 L.mol-1.cm-1,应用于水中羟胺和试剂丁二酮肟含量的测定,结果满意.     

反相高效液相色谱法测定饲料添加剂阿散酸中的阿散酸及掺假物质对氨基苯磺酸

建立了用于饲料添加剂阿散酸质量控制的反相高效液相色谱法。采用的色谱条件: Waters Bondapak C18柱(150 mm×4 mm, 5 μm)分离,以甲醇-水(用稀磷酸调节pH至2.9) (1:4, v/v)作流动相,流速1.0 mL/min,紫外检测波长为244 nm。在优化的色谱条件下,阿散酸和掺假物质对氨基苯磺酸在3 min内实现了基线分离。阿散酸和对氨基苯磺酸的线性范围均为5～200 mg/L,检出限(S/N=3)分别为0.20 mg/L和0.15 mg/L。该方法简便快速,适合饲料添加剂阿散酸的分析以及监测对氨基苯磺酸掺假。     

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.