Abstract: This application describes the use of LC/Ion Trap MS and LC/TOF for the identification of and quantization of terbutylazine in olive oil samples. The analysis by ion trap was achieved in MS/MS mode, monitoring the characteristic fragment ion at m/z 174. The identification by LC/TOF was accomplishment with accurate mass, along with the accurate mass of chlorine isotope cluster present in terbutylazine. The accuracy typically is better than 2 ppm. The method sensitivity, linearity precision accuracy matrix effect, and limit of detection were also studied.