The extraction of quinolones from fortified fish fillets used in this work was based on solvent extraction (solid-liquid extraction, SLE), followed by clean-up by solid-phase extraction (SPL), which is considered a standard procedure for this propose, As quinolones are soluble in polar organic solvents, and as trichloroacetic acid (TCA) is a well-recognized protein precipitation agent, a mixture composed of and aqueous TCA solution (10%) and methanol was used as the extraction solution in the SLE step. In order to select the best conditions for clean-up by SPE, it is important to take into consideration the physicochemical characteristic of the largest substances (Fig 1). Reversed phase cartridges retain the uncharged quinolones when dissolved in a polar solvent. To develop the SLE method, different proportions of TCA and methanol were evaluated to obtain the best mixture enabling both efficient quinolones extraction from the tilapia fillets and retention on the reversed phase cartridges. In this way, the proportions of the aqueous TCA solution (10%) and methanol selected were 8:2 (v/v). In order to optimize the extraction procedure, the following SPE cartridges were evaluated: Oasis-HLB, Strata-X, and BondElut. The quantity of tilapia fillet sample (0.5 g, 1 g, and 2 g) and elution solvent (aqueous ammonia-CAN, glacial acetic acid-ACN) were also varied. The optimum results were achieve by use of Oasis-HLB cartridges, using 2 g fish sample and aqueous ammonia-ACN at 2:8 v/v as the elution solvent (Fig 2). The extraction efficiency for all the quinolones under these conditions ranged from 59 to 75% and recoveries ranged from 89 to 112%.