Abstract: In acidic medium，Hg( Ⅱ) and Br－can react with methylene blue ( MB) to form the ion－pair complex，which can be easily extracted by 1，2－dichloromethane solvent and result in strong fluorescence． The maximum emission wavelength ( λem ) is 689 nm; fluorescence intensities are proportional to concentrations of the Hg( Ⅱ) over the range 0． 01 ～ 6． 4( g /mL with a detection limit ( DL) of 3 ng /mL． The method was applied to the determining of trace amount mercury in Wujiang water with satisfactory results．

Key words: mercury, solvent extraction, ion-pair complex, fluorescence

摘要： 在酸性介质中，Hg2+、Br－和亚甲蓝形成离子缔合物，该缔合物易被1，2－二氯乙烷等有机溶剂所萃取，在689 nm处有较强荧光。在优化的实验条件下，在0．01～6．4μg/mL范围内，Hg与荧光强度成正比，该法综合荧光的高 灵敏度特点和溶剂萃取的浓缩作用，使其灵敏度得到极大提高，检出限为3ng/mL，更适合用于痕量汞的测定。经 过用于乌江水样中痕量汞的实际测定，结果比较满意。

关键词: 汞, 溶剂萃取, 离子缔合物, 荧光