The new compound - flibanserin - begun to appear as a synthetic adulterant in counterfeit herbal supplements used to stimulate women sexual drive. It was detected in two samples submitted to the Polish National Medicines Institute for analysis. The second sample contained also tadalafil. This study presents the LC method development which enables the determination of flibanserin and tadalafil. It employs three different detectors charged aerosol detector (CAD), diode array detector (DAD) and mass spectrometer (MS). The conditions of the elaborated method were optimized to obtain the highest sensitivity and the best resolution, especially the separation of icariin - the natural compound observed often in supplements for sexual disorders. The validation of the method proved good linearity, good accuracy and precision of the measurements recorded by all three detectors. Additionally, for CAD data, an alternative calculation method using a unified calibration function was presented and evaluated. It seems that this is the way to overcome the problem of non-availability of the reference standard of a target compound. Flibanserin content was quantified using the data of other reference standard (tadalafil). The inaccuracy of proposed indirect determination was found to be ±3%. A statistical evaluation proved that the results obtained with all detection modes and the results calculated using a unified calibration were not significantly different (p>0.05).