Identification and quantification of 77 pesticides in groundwater using solid phase coupled to liquid-liquid microextraction and reversed phase liquid chromatography

This paper describes a method for the extraction, separation, identification, and quantification of 77 pesticides (neutral, acidic, and basic) including some 8-triazine metabolites. The method is appropriate for organically (e.g. with humic acids) highly loaded groundwater samples. A comparative study of a pH-controlled mixed solid phase (LiChroprep RP18/LiChrolut EN) extraction with different desorption solvents (acetonitrile or acetonitrile and dichloromethane/methanol) is elaborated. A subsequent liquid-liquid microextraction reduces matrix effects,The pesticides in the sample are separated using RP-HPLC, detected, and identified by diode array. The efficiency is illustrated on a natural groundwater sample from a phreatic aquifer.