Enhanced fluorescence from o-phthalaldehyde and fluorescamine fluorophores using Triton and β-cyclodextrin

Mexiletine— and lysine hydrochloride—o-phthalaldehyde and mexiletine hydrochloride—, cysteine—, cysteamine—, homocysteine— and lysine hydrochloride—fluorescamine derivatives were subjected to Triton and β-cyclodextrin enhancement treatments. Of several classical fluorescence-enhancing reagents tested (Triton, β-cyclodextrin, sodium dodecyl sulphate, Brij), Triton provided the best results, followed by β-cyclodextrin. Increases in fluorescence emission by a factor of up to about 10 (mexiletine—fluorescamine—Triton X-100) were observed, with a generally negligible influence of the enhancing reagents on the excitation and emission maxima. Fluorescence enhancement by the addition of a suitable reagent solution to the final analyte solution may, in specific instances, enhance the detectability of native or chemically induced fluorophores.     

Zn—TppS4极谱络合物吸附波的研究：中草药天麻,川芎,当归中锌的测定

锌是人体必需的微量元素之一。它具有重要的生理功能和营养作用,是合成脱氧核糖核酸(DNA),核糖核酸(RNA)和蛋白质必需的金属离子。锌是DNA,RNA聚合酶等80多种酶的组成成分及激剂,直接影响细胞代谢,免疫过程,细胞分裂和再生。最近美国有人提出缺     

A new method for inversion of hydroxyl group of carbocyclic nucleosides

The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me_3SiCl,KCN and a catalytic amount of NaI in DMF/CH_3CN.     

1,3-二羧甲基咪唑盐酸盐热分解过程研究

离子液体是继超临界流体之后的一类新的绿色溶剂,因其具有一系列独特的性质,作为溶剂和反应介质已广泛应用于有机合成、催化反应工程、电化学、分离分析等领域.随着研究和应用的逐渐深入,仅仅将离子液体作为溶剂和反应介质已不能满足要求,使离子液体带上某些官能团,从而赋予其特定的功能,是相关领域的一个研究热点.1,3-二取代咪唑盐是一类常用的离子液体,对其功能化具有重要意义.1,3-二羧甲基咪唑的制备简单,将它与不同的酸如盐酸、磷酸、硼酸等进行反应,可得到对称二羧甲基取代的咪唑盐.这类咪唑盐作为缩聚单体与二醇或二胺反应,可得到每个重复链节上都含有咪唑阳离子的新的功能性聚酯或聚酰胺;如果用其掺杂导电聚苯胺,因其挥发性低则有可能大大提高聚苯胺的导电寿命.     

氧化藏红T褪色催化荧光法测定痕量钒

研究了在酸性介质中柠檬酸存在下，痕量钒（Ｖ）催化溴酸钾氧化藏红Ｔ的褪色反应及其动力学条件，建立了催化荧光测定痕量钒的新方法。催化反应在沸水浴中进行８ｍｉｎ，为假零级反应，反应的表观活化能力为９９．２１ｋＪ／ｍｏｌ，反应速度常数为０．１２／ｓ；该方法的检出限为２．２×１０＾－８ｇ／Ｌ；线性范围为０．２￣２．４μｇ／Ｌ研究了共存离子的影响，用于人发和煤灰中痕量钒的测定，结果令人满意。     

Sequential Injection Photometric Determination of Molybdenum Using Organic Wetting Film Extraction

Wetting film extraction was combined with colorimetry to determine nanogram amounts of molybdenum(VI). The simple extraction procedure enhanced sensitivity and selectivity while maintaining a high sample throughput. Extraction and back extraction steps were exploited to exclude interference from the 31 metal species and 11 anions tested. In the first step, molybdenum(VI) was extracted into a toluene film as an ion paired complex. Molybdenum(VI) reacted with thiocyanate to form anionic molybdenum(V) and/or molybdenum(VI) thiocyanate complexes. The complexes were extracted into a toluene film containing tetraheptylammonium bromide as ion pairing reagent. The thiocyanate ligands were displaced by 1,5-diphenylcarbazone (DPC) to form a more intensely colored complex (λ_max= 540 nm). DPC was introduced in the back extraction solvent, methanol. The relative standard deviation was 2.5% for 50 ng ml⁻¹of molybdenum(VI) (n= 10) at a rate of 25 samples h⁻¹. The detection limit (3 × baseline noise) was 2.5 × 10⁻⁸M.     

The Surface Imprinted Polystyrene Beads Prepared via Emulsion Templates

In this paper, the surface imprinted cross-linked polystyrene beads were prepared via suspension polymerization with styrene (St), divinylbezene (DVB), polyvinyl alcohol (PVA1788),the mixture of Span 85 and xylene or the mixture of Span 85 and paraffin as monomer,cross-linking agent, dispersion stabilizer and templates, respectively. The results indicate that there are dense cavities on the surface of beads, and the diameter and density of cavity are related with the composition and amount of emulsion template. The forming mechanism of cavity from thermodynamics and dynamics was proposed.     

The pH-dependent role of superoxide in riboflavin-catalyzed photooxidation of 8-oxo-7,8-dihydroguanosine

[reaction: see text]. The riboflavin-catalyzed photooxidation of 2',3',5'-tri-O-acetyl-8-oxo-7,8-dihydroguanosine generates a radical intermediate that is competitively trapped by H(2)O, O2(-)(*), or O(2). The products of H(2)O trapping have been previously described as the spiroiminodihydantoin (pH >or= 7) and iminoallantoin/guanidinohydantoin (pH < 7) nucleosides. Trapping by O2(-)(*) leads to the oxaluric acid (pH or= 8.6) pathways (R' ', R' ' = H or 2,3,5-tri-O-Ac-ribofuranosyl). The pH-dependent role of superoxide was probed using Mn-SOD and compared to guanosine and 8-methoxyguanosine photooxidation.     

Synthesis of 5-ethynylorotic acid

Condensation of 2,4-dimethoxy-5-iodo-6-carbomethoxypyrimidine ( 10 ) with copper (I) 3-tetrahydropyranyloxyprop-1-ynide ( 4 ) afforded 2,4-dimethoxy-5-(3′-tetrahydropyranyloxyprop-1′-yn)-6-carbomethoxypyrimidine ( 11 ), which was hydrolyzed to produce 2,4-dimethoxy-5-(3′-hydroxyprop-1′-yn)-6-carbomethoxypyrimidine ( 12 ). Oxidation of 12 with dimethyl sulfoxide-oxalyl chloride reagent gave the acetylenic aldehyde ( 13 ), which on treatment with sodium methoxide in dry tetrahydrofuran yielded 2,4-dimethoxy-5-ethynyl-6-carbomethoxypyrimidine ( 14 ). The trimethylsilyl derivative ( 15 ) was deprotected by sequential treatment with iodotrimethylsilane and aqueous sodium hydroxide, leading to the formation of 5-ethynylorotic acid ( 1 ).     

(Pd-Cu)/C上苯乙烯氧化羰化合成肉桂酸甲酯的研究

在常压130℃下研究了Pd-Cu催化剂组成,反应温度,少量添加剂和原料气中O_2含量等对苯乙烯氧化羰化合成肉桂酸甲酯的影响,并对催化剂的形、相态进行表征.发现O_2有双重作用;O_2不仅使Pd-Cu之间的价态循环,而且能抑制反应过程中饱和苯丙酸甲酯的生成.指出催化反应中Pd-Cu之间的催化协同效应促进了产物的生成.初步讨论了本反应的机理.