ASE-HPLC法测定黄姜中薯蓣皂甙元的含量

采用ASE200快速溶剂萃取机提取技术和高效液相色谱法,测定黄姜中薯蓣皂甙元的含量。确定了ASE200提取条件以及HPLC测定条件,以甲醇作为流动相,流速1mL/min,UV检测器,测定波长210nm,采用YWGC18柱(150mm×4.6mmi.d.,10μm)。测定皂甙元的线性范围为0.01～2.93g/L,r=0.9996,样品检出限为0.2mg/L,加标回收率为97.1%～99.8%,RSD=1.1%(n=7)。     

甲基红氧化褪色光度法测定食盐中碘

基于在盐酸介质中 ,碘酸根在溴化钾的催化作用下使甲基红氧化褪色的反应 ,建立了测定微量碘的新方法。方法的线性范围为 8μg/2 5mL～ 2 2 μg/2 5mL ,表观摩尔吸收系数为 6 .5× 1 0 4 L·mol- 1 ·cm- 1 ,已用于食盐中碘的测定。     

测定痕量硅的超高灵敏显色反应的研究

本文详细研究了在阿拉伯树胶存在下,硅钒钼蓝-罗丹明B水相光度法测定硅的新方法.四元络合物的最大吸收峰在595nm处,表观摩尔吸光系数为1.0×10~6·L·mol~(-1)·cm~(-1),Sandell灵敏度为2.25×10~(-5)μgSi/cm~2。硅含量在0～0.7μg/25mL范围内遵守比尔定律。方法用于水中痕量硅的测定,结果令人满意。     

气浮溶剂浮选光度法测定食品中痕量SO32-的研究

提出了碘溴化十六烷基三甲胺缔合体系溶剂浮选褪色光度法测定SO2-3 的新方法,方法的摩尔吸光系数ε365=3.0×105L·mol-1·cm-1,最大吸收波长为365 nm,测定5.0μg/50 mLSO2-3 6次,RSD为1.8%,线性范围为0~30μg/50 mL,方法应用于食品中SO2-3 的测定。     

薄层色谱-紫外可见分光光度法同时测定食品中的苏丹红Ⅰ～Ⅳ

建立了测定食品中苏丹红色素含量的新方法——薄层色谱-紫外可见分光光度法,对影响测定的因素如样品预处理方式、展开剂等进行了讨论,检测苏丹红Ⅰ~Ⅳ的线性范围分别为0.5~14μg/mL,0.5~10μg/mL,0.5~15μg/mL,0.5~15μg/mL,线性相关系数均为0.999,检出限均为0.05μg/mL。该方法测定结果与国家标准方法测定结果基本一致。     

差示分光光度法测定茶多酚的含量

基于茶多酚在酸性条件下还原 Fe3+ 为 Fe2 + ,Fe2 + 与铁氰化钾生成可溶性兰色配合物 KFe[Fe (CN) 6 ],用差示分光光度法测定其吸光度 ,从而可间接测定茶多酚的含量。方法线性范围为 2μg/m L～ 1 2μg/m L ,ε=1 .97× 1 0 5L· mol- 1· cm- 1,RSD=1 .3 % (茶多酚含量 8μg/m L,n=1 1 )。测定结果与标准方法基本一致     

儿童易疲劳与血清中微量元素含量的相关性研究

测定了1562名儿童(其中包括153名易疲劳儿童)血清中Zn、Fe、Cu、Ca、Mn和Pb的含量。研究发现,易疲劳儿血清Ca含量(84.4±12.5μg/mL)显著低于对照组儿童(88.5 4±13.4μg/mL),P<0.05;Fe含量(1.094±0.22μg/mL)显著高于对照组儿童(1.07 4±0.22μg/mL),P<0.05;Mn含量(0.040 4±0.035μg/mL)非常显著高于对照组儿童(0.035 4±0.013μg/mL),P<0.001。     

儿童神经过敏与血清中6种无机元素含量相关性研究

测定了1261名儿童(其中包括73名神经过敏儿童)血清中Zn、Fe、Cu、Ca、Mn和Pb的含量。研究发现,神经过敏患儿血清Zn含量(0.95±0.20μg/mL)显著低于对照组儿童(0.97±0.23μg/mL),P<0.05;Mn含量(0.03±0.01μg/mL)非常显著低于对照组儿童(0.04±0.02μg/mL),P<0.01。     

对磺酸基苯亚甲基若丹宁固相萃取光度法测定水中的汞

研究了对磺酸基苯基亚甲基若丹宁(SBDR)与汞的显色反应,在pH4.0的HAc NaAc缓冲介质中,吐温 80存在下,SBDR与汞反应生成2∶1稳定络合物,该络合物可被WatersPorapak Sep Park C18固相萃取小柱萃取,用乙醇洗脱后在乙醇介质中λmax=520nm,可用分光光度法测定,体系ε=1.16×105L/mol·cm。汞含量在0μg/mL～1.5μg/mL内符合比尔定律,方法可用于水样中汞含量的测定。     

氢化物发生-原子吸收光谱法测定黄芪中硒

黄芪试样经硝酸-过氧化氢消解,用氢化物发生-原子吸收光谱法测定黄芪中总硒、无机硒和有机硒的含量。使用15 g·L^-1硼氢化钾-3 g·L^-1氢氧化钠溶液与溶液中硒离子反应生成氢化物。分析中采用载气流量240 mL·min^-1。硒的质量浓度在60μg·L^-1以内与吸光度呈线性关系,方法的检出限（3σ）为0.21μg·L^-1。应用此法测定黄芪中硒的含量,总硒测定值为105μg·g^-1、硒（Ⅳ）测定值为15μg·g^-1、硒（Ⅵ）测定值为9μg·g^-1、有机硒测定值为81μg·g^-1。黄芪中的硒主要存在形式为有机硒,占总硒含量的77%。     

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.     

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%).     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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 substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.