Extracting Carbendazim Residue in Lettuce Using Matrix Solid-Phase Dispersion

This study aimed for practically unsophisticated, less time- and cost-consuming techniques in extracting and analyzing carbendazim residue in lettuce. The used method was matrix solid-phase dispersion. By mechanically blended diatomaceous earth with the lettuce that spiked standard carbendazim concentrations of 1, 3, and 5 µg/g, by using mortar and pestle, a bonded-phase was induced between them. The amounts of lettuce were 0.5, 1.0, 3.0, and 5.0 g, while the amounts of the solid support were 0.5, 1.0, 2.0, 4.0, and 6.0 times those of the lettuce quantities. The mixtures were filled in plastic syringes and different solvents which were dichloromethane, methanol, ethyl acetate, and the 70:30 mixture of dichloromethane and methanol were poured one at the time to elute the carbendazim and then evaporated. The residual carbendazim was re-dissolved using methanol and determined its concentration. The obtained concentration was compared to the initial spiked concentration to determine the recovery percentage. The acceptable range is 80-110%, based on the Association of Analytical Communities. It was found that the appropriate amount of lettuce for this method was 1.0 g, with the ratio of 1 : 4 between lettuce and diatomaceous earth. The suitable solvent for eluting carbendazim in a descending order was methanol > a mixture between dichloromethane and methanol > ethyl acetate > dichloromethane. The suitable amount of solvent was 40 mL. The findings can be applied to other pesticide residue in agricultural products since it is not complicated and use small amount of chemical substances. Keywords : carbendazim, pesticide extraction and analytical procedures, matrix solid-phase dispersion