A solid-phase extraction based soil extraction method for pesticides of varying polarity

Solid-phase extraction (SPE) is an innovative method for efficiently and quantitatively extracting pesticides from large numbers of soil samples. An extraction method using commercially available SPE columns has been developed and tested using three herbicides of varying polarity: bromacil [5-bromo-6-methyl-3-(1-methylpropyl)-2,4(1H,3H)pyrimidinedione], napropamide [N,N-diethyl-2-(1-naphthalenyloxy)propanamide], and prometryn [N,N'-bis(1-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine]. The soil sample is shaken with a methanol/water mixture and centrifuged. The supernatant is then diluted with a concentrated NaCl solution, and drawn through an SPE column. The sorbed pesticides are finally eluted from the column with methanol.