Alachlor is a chloroacetanilide family herbicide which inhibits parts of the gibberellin pathway. The EPA classifies alachlor as slightly toxic and set the maximum contaminant level at 2 ppb. The EU banned alachlor in 2006. Obelisc R was used to retain alachlor and separate it from impurities. 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 alachlor.