Analytical developments for 47 pesticides: first identification of neutral chloroacetanilide derivatives in French groundwater

A new analytical methodology for neutral derivatives of chloroacetanilides made it possible to detect, for the first time in a European groundwater monitoring campaign, three metabolites (hydroxymetolachlor, metolachlor morpholinone and deschlorometolachlor) in addition to ethane sulfonic acid (ESA) and oxanilic acid (OXA) metabolites, which were first detected in 2009. The analytical method involves solid phase extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). Recoveries ranged from 64 to 101%, and limits of quantification were validated at 5, 10 or 20 ng/L, depending on the molecule, in natural water. Most of the chloroacetanilide metabolites were synthesised, as many standards are not commercially available.