Abstract
An analytical method for pesticide residue for agricultural products was developed using combination column of macroporous diatomaceous earth (MDE) and graphitized carbon black (GCB). The on-column liquid–liquid partition was performed by the following procedure. The concentrated sample extract was diluted with an equal volume of acetonitrile and transferred into the MDE column, and the residue pesticides were eluted with hexane. It was possible to elute the non-polar pesticides (log POW>4.3) from the MDE column by using a smaller volume of organic solvent. One hundred-seventy-three of 238 pesticides were recovered at more than 70% with hexane from the MDE columns when applied in acetonitrile–water (1 : 1, v/v) solution. After eluting from the MDE column, the elution profiles with the GCB cartridge indicated that the majority of pesticides could be eluted with common organic solvents such as hexane, ethyl acetate and acetone. The applicability of this method was evaluated by the recovery from 5 fortified agricultural products (cucumber, spinach, tomato, carrot and chinese cabbage) at 0.02 and 2.0 μg/g. The recovery of 2 synthetic pyrethroid insecticides and 7 organic chlorine pesticides ranged from 81% to 113%, and the limit of detection was 0.005 μg/g.
