The ability to separate complex mixtures of structurally similar compounds within one method is highly desirable. Additionally, compounds of related structures may also be isobaric with similar fragmentation, rendering them unidentifiable by MS/MS. In these cases, it is essential that these compounds be baseline separated chromatographically. Several compound duos that require baseline separation for accurate quantitation have been successfully resolved using UCT’s Selectra® DA HPLC column including 2C-phenethylamine isomers, Ephedrine and Psuedoephedrine, Methamphetamine and Phentermine, and Ethylone and Butylone. By choosing the correct column chemistry, mobile phase combination and gradient, baseline separation can be accomplished when needed.