A New Spectrophotometric Method for Determination of Vitamin B12 as Cobalts

Abstract

A spectrophotometric method for determination of Vitamin B₁₂ (Cyanocobalamin) as cobalt in pharmaceutical preparations is described. The sample is first decomposed by concentrated sulfuric and nitric acids and the dry residue is solubilized in distilled water. The cobalt present is then spectrophotometrically determined at Λ= 317 nm as Co-HMPA-SCN complex. The complex is stable for a long time in the range of pH 3–10. The presence of many other metal cations does not interfere.     

Highly Thiocyanate‐Selective PVC Membrane Electrode Based on Lipophilic Ferrocene Derivative

A novel anion‐selective PVC membrane electrode based on bis‐[(3‐ferrocenyl)‐(2‐crotonic acid)] copper(II) complex [Cu(II)‐BFCA] as neutral carrier is described, which demonstrates excellent potentiometric response characteristics toward thiocyanate ion and anti‐Hofmeister selectivity sequence in following order: SCN^?>I^?>ClO >Sal^?>Br^?>NO >Cl^?≈NO >SO >SO . The electrode shows a near‐Nernstian response for thiocyanate ion in a wide range of 9.0×10^?7–1.0×10^?1 M with a detection limit 6.8×10^?7 M and a slope of ?59.1 mV/decade in pH 5.0 of phosphate buffer solution at 20 °C. The influences of lipophilic cationic and anionic additives on the response properties of the electrode were investigated. High sensitivity and wide linear dynamic range were observed for the electrode in the presence of hexadecyltrimethylammoniumborate (HTAB) as a lipophilic cationic additive. The electrode was successfully applied to the determination of thiocyanate ion in waste water and human saliva.     

紫外吸光光度法测定维生素B12

维生素B12,学名Coα-[α-(5,6-二甲基苯并咪唑基)]-Coβ氰钴酰胺,广存于动植物体中,它与核酸、蛋氨酸的合成,甲基代谢及动物体内蛋白质、脂肪、碳水化合物的代谢有密切关系,是一种应用较广的维生素类药物,其测定方法有紫外吸光光度法、HPLC法、毛细管电泳法等。有报道引入表面活性剂OP可以提高测定VB1、VB2、VB6的灵敏度,     

1,4,7,10-Tetraoxacyclododecane(12-Crown-4) as Neutral Carrier for Lithium Ion in Lithium Ion Selective Electrode

Abstract

1,4,7,10-Tetraoxacyclododecane (12-crown-4) (I) and its lithium complex (II) are used as neutral carriers for lithium ion in polyvinylchloride membrane ion selective electrodes. The lithium response varies with concentration, being near Mernstian at low (10^?5-10^?4 M) concentrations and sub-Nernstian (24-28 aV) at higher concentrations (10^?3 M). The selectivity coefficients K_Li ^Pot _M for II are: Na⁺ (0.12), K⁺ (0.66), Cs⁺ (0.15), Mg²⁺ (1.6 × 10^?4), Ca²⁺ (3.1 × 10^?4), Ba²⁺ (9.5 × 10^?7), NH⁺ ₄ (9.0 × 10^?2), H⁺ (2.2).     

秋兰姆衍生物作中性载体的铜离子敏感电极

合成了二硫化二（Ｎ，Ｎ－１，４－亚丁基）秋兰姆，以此为载体，制备了ＰＶＣ膜铜离子敏感电极。结果表明，电极对铜离子具有好的选择性和灵敏度。线性范围为８．０×１０＾－＾７－１．０×１０＾－＾２ｍｏｌ／Ｌ。实验发现有选定的底液条件下此电极对蛋白质蛮具有较好的响应，线性范围为１２．５－２００ｍｇ／Ｌ。讨论了电极有关性能。     

Vitamin B12 derivatives as natural asymmetric catalysts: enantioselective cyclopropanation of alkenes

Vitamin B(12) derivatives were found for the first time to be general and efficient catalysts for asymmetric cyclopropanation of alkenes with ethyl diazoacetate (EDA). Among several common derivatives, aquocobalamin (B(12a)) was shown to be the most effective catalyst for a variety of alkenes, providing cis-dominant cyclopropanes in excellent yields and moderate enantioselectivity. Reactivity studies under different conditions suggest that the active species in the proposed catalytic cycle is the base-on cob(II)alamin (B(12r)) that is generated possibly via in situ reduction of B(12a) by EDA.     

新型亲脂性菲啰啉衍生物的合成及其自组装性能

以1,10-菲啰啉为起始原料,经溴代、氧化、Suzuki偶联等反应合成了新型亲脂性菲啰啉衍生物——3,8-二(4-联苯基)-5,6-二(十二烷氧基)-1,10-菲啰啉(1),总收率11.24%,其结构经1H NMR,13C NMR和MALDITOF-MS表征。自组装性能研究结果表明,1的自组装体呈规整的微米球状结构。