5-磺基水杨酸在不同酸度下的荧光光谱研究

研究了5-磺基水杨酸(5-Sulfosalicylic acid,SSA)在不同酸度下的荧光光谱性质.酸性条件下,SSA的荧光激发峰λex分别位于201,210,236,297 nm,荧光发射峰λem位于401 nm;随pH值升高,荧光激发峰和发射峰均逐步升高,但激发光谱和发射光谱的形状无变化.碱性条件下,随pH值升高,201,210,236,297 nm的激发峰位置发生红移且强度逐渐降低,261 nm出现一个新的逐步升高的激发峰;401 nm位置的荧光发射峰位置发生蓝移,且强度逐渐降低.pH=2~6,荧光强度随pH值升高而上升;pH=6~9.5,荧光强度基本不变;pH=9.5~13.3,荧光强度随pH值升高而下降.同时,讨论了SSA作为三元酸的解离.

Fluorescence spectra of 5-sulfosalicylic acid at different pH values

Fluorescence spectra of 5-sulfosalicylic acid（SSA） have been studied at different pH values.SSA gives a strong and steady fluorescence with a maximum emission wavelength at 401 nm and excitation wavelengths at 201,210,236 and 297 nm,respectively under acidic conditions.With the increase in pH value,fluorescence intensity of SSA increases gradually in excitation spectrum and emission spectrum without deformations.Under basic condition,the maximum absorption wavelength around 201,210,236 and 297 nm emerged red shift and their fluorescence intensity decreases gradually with the increase in pH value in excitation spectrum.Furthermore a new peak appears around 261 nm and its fluorescence intensity increases gradually with the increase in pH value.Moreover,the maximum absorption wavelength around 401 nm emerged blue shift and its fluorescence intensity decreases gradually in emission spectrum with the increase in pH value.In the range of pH 2—6,fluorescence intensity of SSA increases with the increase in pH value;in the range of pH 6—9.5,fluorescence intensity of SSA is invariable;in the range of pH 9.5—13.3,fluorescence intensity of SSA decreases with the increase in pH value.The dissociation of SSA triploid acid in stages is also discussed.