PHOTOLYSIS OF CYANOCOBALAMIN IN AQUEOUS-SOLUTION

被引：46
作者：
AHMAD, I
HUSSAIN, W
FAREEDI, AA
机构：
[1] Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Karachi, Karachi
来源：
JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS | 1992年 / 10卷 / 01期
关键词：
CYANOCOBALAMIN; HYDROXOCOBALAMIN; 2-COMPONENT SPECTROPHOTOMETRIC ASSAY; PHOTOLYSIS; PH EFFECT;
D O I：
10.1016/0731-7085(92)80004-7
中图分类号：
O65 [分析化学];
学科分类号：
070302 ; 081704 ;
摘要：
Cyanocobalamin is photolysed in aqueous solution to produce hydroxocobalamin. The kinetics of photolysis has been studied at pH 1-12 using a newly developed spectrophotometric method for the simultaneous determination of the two compounds at 550 and 525 nm or 361 and 351 nm. Cyanocobalamin follows zero-order kinetics at the pH values studied and the rate is catalysed by both hydrogen and hydroxyl ions. The log k-pH profile indicates that cyanocobalamin has maximum stability near pH 7. The cationic species appears to be more susceptible to photolysis than the neutral form. The rate constant for the reaction at pH 1 is 1.32 x 10(-7) Mol l-1 min-1 compared with 0.050 x 10(-7) mol l-1 min-1 at pH 7.
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页码：9 / 15
页数：7
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