Analytical method for the determination of metolachlor, acetochlor, alachlor, dimethenamid, and their corresponding ethanesulfonic and oxanillic acid degradates in water using SPE and LC/ESI-MS/MS.

A Good Laboratory Practices (GLP) validated, multiresidue analytical method is presented for the determination of the chloroacetanilide herbicides metolachlor, acetochlor, and alachlor, the chloroacetamide herbicide dimethenamid, and their respective ethanesulfonic (ESA) and oxanillic (OA) acid degradates in ground and surface water. A 50-mL water sample is subjected to purification using a C-18 SPE column. The four parent components and their eight ESA and OA degradates are isolated using 80/20 methanol/water (v/v) for elution.