A new method for the simultaneous determination of androstenedione, testosterone, 11-oxotestosterone and 11 beta-OH-testosterone in fish plasma using combined techniques of Celite chromatography and radioimmunoassay.

A new method for the simultaneous determination of androstenedione, testosterone, 11-oxotestosterone and 11 beta-hydroxy-testosterone in teleost plasma has been developed. Steroids extracted from the plasma were first separated by Celite chromatography using ethanediol as the stationary phase and different concentrations of ethyl acetate in iso-octane as the eluting solvents. Androstenedione, testosterone, 11-oxotestosterone and 11 beta-OH-testosterone were eluted successively with 0, 10, 15 and 40% of ethyl acetate in iso-octane. The eluted steroid fractions were then quantatively determined by radioimmunoassay. Data on the accuracy, precision, and sensitivity were presented showing that this new assay system was precise and reproducible. As an illustration of its application, this method was used in the present study to determine the plasma androgen levels in Monopterus albus and in methyl-testosterone treated Tilapia mossambicus.