Pirimicarb is an insecticide that controls aphids on vegetable, cereal, and orchard crops. A carbamate insecticide, pirimicarb inhibits activity of the hydrolase acetylcholinesterase. Pirimicarb is a target pesticide in the EURL (European Union Reference Laboratory) EUPT-FF9 2015 a proficiency test for the analysis of a over a hundred pesticides. Primesep 100 and Obelisc R were used to retain pirimicarb and separate it from impurities. Primesep 100 contains embedded acidic ion-pairing groups and Obelisc R contains embedded ionic and hydrophobic groups which can assist in fine tuning separations. Method is LC/MS compatible and can be used as a general approach for analyzing pirimicarb, other organophosphate insecticides, and dozens of other pesticides.