荧光分析法测定邻—羟基苯甲酸和间—羟基苯甲酸

Fluorescence Analysis Determination P-hydroxy Benzoic Acid and Between Adjacent-p-hydroxy Benzoic Acid

使用荧光光度计测定邻—羟基苯甲酸(亦称水杨酸)和二组分混合物的荧光强度,邻—羟基苯甲酸(亦称水杨酸)和间—羟基苯甲酸分子组成相同,均含一个能发射荧光的苯环,但因其取代基的位置不同而具不同的荧光性质。在pH=12的碱性溶液中,二者在410nm附近紫外光的激发下均会发射荧光;在pH=5.5的近中性溶液中,间—羟基苯甲酸不发荧光,邻—羟基苯甲酸因分子内形成氢键增加分子刚性而有较强荧光,且其荧光强度与pH=12时相同。利用此性质,可在pH=5.5时测定二者混合物中邻——羟基苯甲酸含量,间—羟基苯甲酸不干扰。另取同样量混合物溶液,测定pH=12时的荧光强度,减去pH=5.5时测得的邻—羟基苯甲酸的荧光强度,即可求出间—羟基苯甲酸的含量。实验方法好,精密度高。

using fluorescence photometric determination adjacentp-hydroxy benzoic acid（also called salicylic acid） and the second component mixture the fluorescence intensity,adjacent-p-hydroxy benzoic acid（also called salicylic acid） and between the molecular structure of the same——p-hydroxy benzoic acid,all include a emit fluorescent benzene,but because of the different substituents position with different fluorescence properties.In pH = 12 alkaline solution,both in the near 410nm under uv excitation of all can launch fluorescence;In pH = 5.5 nearly neutral solution,between-p-hydroxy benzoic acid not hair fluorescence,adjacent-p-hydroxy benzoic acid by molecular formed in the hydrogen bonding increase molecular rigid and strong fluorescence,and the fluorescence intensity and pH = 12 when the same.Using the nature,can be in pH = 5.5 when both mixture determination-p-hydroxy benzoic acid content,adjacent to no interference between-p-hydroxy benzoic acid.Another take the same amount mixture solution,determination of pH = 12 when the fluorescence intensity,minus the pH = 5.5 when measured adjacent-p-hydroxy benzoic acid fluorescence intensity,can ask out between-p-hydroxy benzoic acid content.Experimental methods,high accuracy.