Diphenamid is an herbicide which selectively controls weedy grasses and broadleaf plants in the production of tobacco, tomatoes, peppers, cotton, and many more commercial crops. Diphenamid is a preemergence herbicide that is surface applied to soils and can be expected to control weeds for 6-8 months. Diphenamid was analyzed on two different stationary phases. Primesep 100 is a reverse phase column that contains embedded acidic ion-pairing groups, while Obelisc R retains with long hydrophobic chains and multiple ionic pairing groups on the surface. Method is LC/MS compatible and can be replicated to analyze dozens of other pesticides.