HPLC Retention of Chlorpyrifos-methyl on Primesep 100 and Obelisc R Mixed-Mode Columns

 

Chlorpyrifos-methyl, an organophosphate pesticide is considered a target pesticide by the EURL (European Union Reference Laboratory) for the EUPT-FF9 2015 a proficiency test for the analysis of a over a hundred pesticides. This compound was separated on two different mixed-mode columns, Primesep 100 and Obelisc R. 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.