2,4,5-T is a synthetic herbicide that defoliates broad-leaf plants. It was a major component of Agent Orange, a defoliant used during the Vietnam War. 2,4,5-T has been replaced by dicamba and triclopyr due to its possible toxicity. 2,4,5-T was included in a proficiency test ran by the EURL (European Union Reference Laboratory) using QuEChERS methodology on acidic pesticides. Obelisc R retained 2,4,5-T because it has a long hydrophobic chain and ionic pairing groups. Primesep 100 retains by reverse-phase and with acid ion-pairing groups. Method is LC/MS compatible and same conditions can be used on many different pesticides.