合成了一种新的荧光试剂3-甲氧基-4-羟基苯甲醛-2-肼基苯甲酸(香草醛缩邻肼基苯甲酸),并用红外光谱法及元素分析法对其分子结构作了验证.试验发现:在pH 5.1的乙酸盐缓冲介质中,上述新试剂在激发波长为308.8 nm时,在476.8 nm波长处出现发射荧光峰,而当在此条件下加入银离子时,由于两者相互反应生成络合物而导致试剂发生荧光猝灭现象,其荧光强度的减弱程度(ΔF)与银离子的质量浓度在3.0~160 μg·L-1范围内呈线性关系.测得此反应对Ag+离子的检出限(3S/N)为0.28 μg·L-1.据此,提出了测定痕量银的新方法.用标准加入法测得方法的回收率在98.3%~103.3%之间.

A new fluorescence reagent,3-mehoxy-4-hydroxybenzaldehyde-2-hydrazinobenzoic acid (MHBHBA) was synthesized and its molecular structure was identified by IR-spectrometry and elementary analysis.It was found that in an acetate buffer of pH 5.1,the new reagent,MHBHBA reacted with Ag+ ion to form a stable complex,leading to quenching of fluorescence of the reagent,and that the magnitude of fluorescence quenching of MHBHBA kept linear relationship with mass concentration of Ag+ ion in the range of 3.0-160 μg·L-1,when measured at the wavelengths of (λex) 308.8 nm and (λem) 476.8 nm.Detection limit (3S/N) found was 0.28 μg·L-1.Based on these facts,method for determination of trace amount of silver was proposed.Recovery of the method was tested by standard addition method,giving values of recovery ranged from 98.3% to 103.3%.