In this research, PT index was studied on nine local samples of olive oil and two foreign ones using High Performance Size – Exclusion Chromatography. The results indicated that PT was available in nearly all samples. In other words, most of the purchased brands had some purified oil though all had phrases like %100 purified or virgin olive oil imprinted on them. Namely the M3%1, M4%0.78 and M5% 0.36 had the most and M6%0.04 and M2%0.09 the least PT respectively.