Abstract: The spectrofluorimetric method is described for assaying ofloxacin in musculature of crucian, eel, carp and tilapia. The ofloxacin in fish samples was extracted with acidic acetonitrile and defatted with hexane. The aqueous phase was determined by spectrofluorimetry using Briston-Robinson buffer solution(pH 4.0) and detected at λex 294nm,λem 496nm. The linear range of the concentration of ofloxacin is 0.03～0.20μg/ml with r=0.9929. The limit of detections(LOD) is 0.005μg/ml. The recoveries of ofloxacin is 76.0% to 94.5%. The variation coefficient intra assay is 2.14% to 6.50% and inter assay is 3.02% to 9.78%。

Key words: ofloxacin, spectrofluorimetry, crucian, eel, carp, tilapia, residues