Abstract This work developed a fast and simple method for the quantification of two important ?-agonists, ractopamine (RAC) clenbuterol (CLEN) in animal urines. The was based on micro-extraction by mixed mode monolithic material analysis HPLC-UV UHPLC-Q Exactive TM Plus Orbitrap mass spectrometer. A functional monolith with nonpolar ester-based structure containing polar carboxylic groups therm...