抗氧剂L-抗坏血酸在水溶液中氧化反应速率常数的测定  

Determination of oxidation rate constant of antioxidant L-ascorbic acid in aqueous solution

作　　者：舒晓明[1] 蒋露[1] 史焱[1] 李霖[1] 詹先成[1] 曹呈勇[1] 李成容[1] 李琳丽[1] 

机构地区：[1]四川大学华西药学院,四川成都610041

出　　处：《华西药学杂志》2005年第6期507-509,共3页West China Journal of Pharmaceutical Sciences

基　　金：国家自然科学基金(批准号:30472104)

摘　　要：目的测定抗氧剂L-抗坏血酸在3种缓冲溶液中与氧反应的速率常数。方法反应液中持续通入空气,在保证溶液中氧浓度恒定的情况下,用碘量法测定不同时刻抗坏血酸溶液的浓度,作出降解曲线,拟合降解公式并计算降解速率常数。结果抗坏血酸在中性和弱碱性溶液中为表观一级反应,氧化反应速率常数分别为(9.24±0.8)×10-3h-1,(100±1)×10-3h-1;在弱酸性溶液中为表观1/2级反应,氧化反应速率常数为(8.73±0.14)×10-5mol1/2·L-1/2·h-1。结论在弱碱性条件下L-抗坏血酸反应速率较快,抗氧化能力较弱;在中性和弱酸性条件下反应速率较慢,抗氧化能力较强。OBJECTIVE To determine the oxidation rate constants of antioxidant L - ascorbic acid in aqueous solution. METHODS Snfficient air was inflated into the solution continually to keep the concentration of dissolved oxygen steady. The residual concentrations of L - aseorbic acid in the solutions were determined by iodimetry, and the concentrations of dissolved oxygen were by electric potential method. The reaction rate constants were obtained from linear regressions. RESULTS The degradation of antioxidant L - aseorbic acid obeyed the pseudofirst- order kinetics in neutral and weak alkaline, and 0.5 - order kinetics in weak acid. The apparent rate constants were （9.24 ± 0.80） ×10^- 3 h^- 1 in neutral, （ 100 ± 1 ） ×10^- 3 h^- 1 in weak alkaline and （ 8.73 ±0.14） × 10^- 5 mol^1/2. L^-1/2. h^- 1 in weak acid, respectively. CONCLUSION The L - ascorbic acid is found to possess stronger antioxidant activity in neutral and weak acid solutions than in weak alkaline

关 键 词：L-抗坏血酸 抗氧剂 氧化反应速率常数 

分 类 号：R913[医药卫生—药学]