In this work, we propose a new quick and accurate analytical method by UHPLC–QqQ-MS/MS which is able to identify free phytoprostanes in olive and refined sunflower oils. The recovery provided high extraction efficiencies ranging from 102.90% to 140.64% using Strata-XAW cartridge. The intra-day and inter-day variations for all target compounds ranged from 2.24% to 13.64% and 0.01% to 13.69%, respectively, and the accuracies for these parameters varied from 80.33% to 119.64% and from 80.34% to 119.90%, respectively. Results obtained reflect that refined sunflower presented more series of phytoprostanes and a 20 and 8-fold higher quantity than two types of olive oil: Extra virgin olive oil and olive oil, (containing half virgin extra olive oil and half refined olive oil). The manufacture process could be the key for the different phytoprostane production since most of the plant oils are subjected to a refining treatment.