HPLC Analysis of MCPA on Primesep and Obelisc Mixed-Mode Columns



MCPA (4-Chloro-2-methylphenoxy)acetic acid) was synthesized to control broad-leaf weeds such as thistle and dock. MCPA forms complexes with metal ions and increase their bioavailability. A single residue method was developed and used by the EURL (European Union Reference Laboratory) for acidic pesticides. MCPA was separated by both Obelisc R and Primesep 100. Primesep 100 is a reverse-phase column with embedded acidic ion-pairing groups while Obelisc R is a mixed-mode column with separates using ionic groups and a long hydrophobic chain. Methods are LC/MS compatible and able to be used with many pesticides.