Benfluralin is a dinitroaniline herbicide used on grasses and weeds. The EURL (European Union Reference Laboratory) included benfluralin in a study using a multiresidue method by GC-MS/MS in olive oil. Obelisc R was used to separate benfluralin and its impurities using a single multiresidue method, which can be used for many pesticides. Obelisc R contains embedded ionic and hydrophobic groups which can assist in fine tuning. Method is LC/MS compatible and can be used as a general approach for analyzing benfluralin and dozens of other pesticides.