对羟基苯甲酸乙酯和对羟基苯甲酸丙酯稳定性的研究

摘要

采用紫外分光光度法研究了温度、光照、酸碱度、金属离子、氧化剂、还原剂、碳水化合物对对羟基苯甲酸乙酯和对羟基苯甲酸丙酯稳定性的影响。结果表明：光照、温度（≤80℃）基本不影响对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的稳定性；中性和酸性条件下对羟基苯甲酸乙酯和对羟基苯甲酸丙酯非常稳定，两者在碱性条件下都不稳定，当NaOH 浓度高于0．001 mol／L时，对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的残留率均低于15％；0．05％的 Zn2＋，Na＋，Mg2＋，Ca2＋，Mn2＋，Cu2＋，Fe2＋和0．02％Cu2＋，0．01％ Fe3＋等金属离子对对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的稳定性影响较小；还原剂Na2SO3浓度≥0．005％时，对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的稳定性明显降低；浓度低于0．25％的氧化剂H2 O2对对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的稳定性影响不大；浓度低于6％的葡萄糖和蔗糖对对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的稳定性几乎没有影响。%The effects of temperature,light,pH value,metal ions,oxidant,reductant and carbohydrates on stabilities of ethyl 4-hydroxybenzoate and propyl p-hydroxybenzoate are investigated.The results show that light and temperature (≤80 ℃)hardly influence the stabilities of ethyl 4-hydroxybenzoate and propyl phydroxybenzoate.In addition,ethyl 4-hydroxybenzoate and propyl p-hydroxybenzoate are stable in neutral and acidic conditions.However,they were not stable in alkaline condition.The residual ethyl 4-hydroxy-benzoate and propyl p-hydroxybenzoate are below 15%as NaOH concentration higher than 0.001 mol/L;the metal ions,such as 0.05%Zn2+,Na+,Mg2+,Ca2+,Mn2+,Cu2+,Fe2+,0.02% Cu2+ and 0.01% Fe3+have small effect on ethyl 4-hydroxybenzoate and propyl p-hydroxybenzoate.Obviously,their stabilities decrease as Na2 SO3 ≥ 0.005%,being influenced little as the oxidant H2 O2 below 0.25%,and remain unaffected as glucose and sucrose below 6%.