单柱离子色谱法测定痕量草酸根离子

本文采用单柱离子色谱系统测定了Ｃ２Ｏ＾２－４，以１．３ｍｍｏｌ／Ｌ葡萄糖酸钠／１．３ｍｍｏｌ／Ｌ硼砂为淋洗液测定Ｃ２Ｏ＾２－４，８常见阴离子Ｃｌ＾－，ＮＯ＾－３，ＨＰＯ＾２－４，ＳＯ＾２－４不干扰测定，Ｃ２Ｏ＾２－４的检出限为０．５７ｍｇ／Ｌ，相对标准偏差为１．０７％，工作曲线的线性范围为０．５７－５００ｍｇ／Ｌ，应用本方法测定了加Ｃ２Ｏ＾２－４的自来水样，Ｃ２Ｏ＾２－４的回收率为９９．５２％。     

磺胺二甲嘧啶钠的二阶导数差示脉冲极谱法定量研究

建立了磺酸二甲嘧啶钠的二阶导数差示脉冲极谱定量分析方法,磺胺二甲嘧啶钠在乙醇－（硼酸－氯化钾缓冲液）－水（体积比７０：２：２８）的底液中,于－１．５６０Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）处出现一良好的二阶导数差示脉冲极谱峰,磺胺二甲嘧啶钠浓度与其峰幅值在０．０６～０．６ｍｍｏｌ．Ｌ＾－１范围内呈非常显著的线性关系（Ｐ〈０．０１）,检出限为９．２ｎｍｏｌ．Ｌ＾－１,已用于注射液中磺酸二甲嘧啶钠的测定。     

4—（6—甲基—2—苯并噻唑偶氮）间苯三酚反相高效液相色谱分离测定钒钴镍铬

作以新研制的４－（６－甲基－２－苯并噻唑偶氮）间苯三酚为柱前衍生试剂，用含１０ｍｍｏｌ／Ｌ的ｐＨ６．８０的ＨＡｃ－ＮａＡｃ缓冲溶液，１０ｍｍｏｌ／Ｌ ＴＢＡ．Ｂｒ和１×１０＾－４ｍｏｌ／ＬＥＤＴＡ的甲醇－水溶液（７８：２２，Ｖ／Ｖ）作流动相，在Ｃ１８柱上，１１ｍｉｎ内反相ＨＰＬＣ分离测定了Ｃｒ（Ⅵ），Ｖ（Ⅴ），Ｃｏ（Ⅱ），Ｎｉ（Ⅱ）。当Ｓ／Ｎ＝３时，其检出限分别是Ｖ（Ⅴ）５．４５ｎｇ，Ｃｏ（Ⅱ）     

柱前衍生反相高效液相色谱分离和测定氨基酸：用N—羟基琥珀酰？…

以Ｎ－羟基琥珀酰亚胺－α－萘乙酸酯（ＳＩＮＡ）为氨基酸的柱前衍生试剂,反相高效液相色谱分离测定了１５种氨基酸。采用含１０ｍｍｏｌ／Ｌ ｐＨ５．０的乙酸－乙酸钠缓冲溶液的甲醇－乙酸乙酯－水（１０／２／８８,Ｖ／Ｖ／Ｖ）溶液为流动相体系。分离测定了７种氨基酸;用甲醇－乙酸乙酯－水（２６／２／７７,Ｖ／Ｖ／Ｖ）分离测定了５种氨基酸;用甲醇－乙酸乙酯－水（４５／２／５３,Ｖ／Ｖ／Ｖ）分离测定了３种氨基酸。     

薄层色谱法同时测定邻苯二酚、间苯二酚和对苯二酚异构体

研究了在自制硅胶薄板上邻苯二酚,间苯二酚异构体的薄层色谱特性。展开剂为本：乙醚：冰醋酸＝７：２：１（Ｖ／Ｖ／Ｖ）,Ｒｆ值分别为０．５９,０．５３,０．４８。检测限分别为１．０７×１０＾－４,１．６４×１０＾－４,１．９０×１０＾４ｍｏｌ／Ｌ。其他常见酚不干扰测定。可应用于实际样品的测定,回收率为９６％－１０４％。     

微分电位溶出法测定人发中铜铜镉锌的研究

本文报道了０．００２５ｍｏｌ．Ｌ＾－１ＨＣｌ－０．２ｍｏｌ．Ｌ＾－１ＮＨ４Ｃｌ底液中连续测定人发中铜、铅、镉、锌的微分电位溶出法。四元素峰电位分别为－０．２０Ｖ，－０．４６Ｖ，－０．６７Ｖ，－１．０２Ｖ（ＳＣＥ），峰形好，灵敏度高，干扰少，测定发样相对标准偏差≤４．３％，回收率为９７．６％－１０４．６％。并对ＨＮＯ３－ＨＣｌＯ４和ＮＨＯ３－Ｈ２Ｏ２消化发样进行了比较。     

牡丹皮中丹皮酚的二阶导数差示脉冲极谱法定量研究

建立了中草药牡丹皮中丹皮酚的二阶导数差示脉冲极谱定量分析方法。丹皮酚在１ｍｍｏｌ／Ｌ－１ｍｍｏｌ／Ｌ氯化钾－水（１：１：２３）的溶液中,于－１．６．３０Ｖ（ｓ ａｇ／ＡｇＣｌ）处出现一良好的二阶导数差示脉冲极谱峰,其峰幅值与丹皮酚在０．１～０．６ｍｍｏｌ／Ｌ范围内呈非常显著的线性关系（Ｐ〈０．０１）,检测限为９．２ｍｍｏｌ／Ｌ。本法简便、快速、灵敏,且结果准确。     

高效液相色谱法测定小鼠脑组织单胺递质及其相关化合物

采用苯基柱等度洗脱分离,自然荧光检测法,直接测定小鼠脑组织匀浆中单胺递质及其相关化合物。优化出了最佳色谱条件,流动相为２０ｍｍｏｌ／Ｌ柠檬酸三钠（ｐＨ４．５０）－甲醇（９５：５,Ｖ／Ｖ）;柱温为３５℃。该方法能同时检测８种化合物。最低检测限为１．０－２．５μｇ／Ｌ,回收率均在９３５以上;线性范围为１．０μｇ／Ｌ－１．０ｍｇ／Ｌ。     

依诺沙星在混合粘合剂碳糊电极上的电化学特性

制备了混合粘合剂碳糊电极。在０．０１５ｍｏｌ／Ｌ，磷酸－０．１０ｍｏｌ／ＬＫＣｌ溶液中，依诺沙星在该电极上于－１．２６Ｖ处产生一灵敏的阴极溶出伏安峰。在－０．９０Ｖ富集９０ｓ后，依诺沙星的线性范围为３．１×１０＾－７－１．２×１０＾－５ｍｏｌ／Ｌ，检测下限为９．４２×１０＾－８ｍｏｌ／Ｌ，所提出的方法用于尿液和血清中依诺沙星测定，回收率在９６％－１０３％之间。     

铅-邻菲罗啉-镉试剂体系极谱法测定铅

在ｐＨ７．１的六次甲基四胺和０．１ｍｏｌ／Ｌ的ＫＣｌ底液中,Ｐｂ＾２＋－ｐｈｅｎ－Ｃａｄｉｏｎ于－０．４３Ｖ处产生灵敏的极谱波,铅浓度在３×１０＾－８￣１×１０＾－６ｍｏｌ／Ｌ之间与峰电流成良好的线性关系,检测下限可达１×１０＾－８ｍｏｌ／Ｌ,线性回归方程为Ｉｙ＝５６５．０ Ｃｘ－４１．１０,相关系数为０．９９８１。测定废水中铅的标准加入回收率可达９６．２％￣１０１．７％。     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Studies of Photoionization of CF3 I by Femtosecond Time-resolved Mass Spectrometry

The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved.