High-performance liquid chromatographic determination of gossypol and gossypolone enantiomers in fish tissues using simultaneous electrochemical and ultraviolet detectors

There is a need to measure dietary transfer of gossypol and its metabolite, gossypolone in aquatic animals because of common use of cottonseed meal as a feed ingredient and fertilizer. The analytical method for gossypol and gossypolone enantiomers, therefore, becomes important. HPLC techniques have been developed by using mainly UV detection. We simultaneously used both UV and electrochemical (EC) detectors, and found that each individual detector has its own advantage which can increase accuracy and ease of identification. EC detection (2.5 and 50 ng/ml) exhibited a significantly lower detection level for both gossypol and gossypolone enantiomers than the UV detection (40 and 300 ng/ml) in the rainbow trout tissues, while UV detectors showed more stable detection than EC. We were able to detect a very low concentration of each gossypol enantiomer by EC but not UV detection especially in seminal plasma. For the first time gossypolone enantiomers were quantified in fish tissues by HPLC and its method was described. The technique, simultaneous adoption of both UV and EC detectors, could be helpful for a very low concentration of gossypol and/or gossypolone enantiomers in tissues of other animals and humans.