17a-Ethynylestradiol or Ethynyl Estradiol (EE2) is a partially synthetic steroidal estrogen and one of the most commonly used drugs for use in oral contraceptives. EE2 is an estrogen since it activates the estrogen receptor. While dosing of EE2 has been lowered in oral contraceptives, worries about water contamination made an analysis of EE2 necessary. Obelisc R and Primesep 100 were used to demonstrate their unique modes of separation. Method is LC/MS compatible and able to be replicated for many different pesticides.