Determination of 17α-methyltestosterone in muscle tissues of tilapia, rainbow trout, and salmon using liquid chromatography-Tandem mass spectrometry

An analytical method was developed to quantitate and confirm the presence of 17 alpha- methyltestosterone in the muscles of tilapia, rainbow trout, and salmon. The method employed two liquid- liquid partitioning steps and two solid- phase extraction columns for sample cleanup. The final extracts were analyzed on an isocratic reverse-phase liquid chromatography- tandem mass spectrometry system with atmospheric-pressure chemical ionization in the positive ion mode. The method was validated at levels from 0.40 to 1.6 ng/ g, with MT-d(3) used as an internal standard. The accuracy was between 100% and 110%, and coefficients of variation of < 10% were obtained for all three fish species. Muscle tissues from dosed fish were also assayed to demonstrate the effectiveness of the method for recovering the parent drug.