A perstraction system using liq.-core microcapsules for pesticide and herbicide removal from aq. environments is proposed. The microcapsules contain an oil, di-Bu sebacate, surrounded by a hydrogel membrane. The extn. efficiency of the capsules was demonstrated with atrazine, methylparathion, ethylparathion, and 2,4-dichloro-phenoxyacetic acid. The results show that all of the tested compds. could be rapidly extd., typically 75% extn. within 10 min using a capsule: liq. vol. ratio of only 3.5% for ethylparathion, and that the rate of extn. increased with increasing hydrophobicity of the compd. to be extd. Higher rates of extn. could be achieved by changing the capsule: liq. vol. ratio. The effect of different liq. core solvents, size of capsules, agitation rate, and treatment with complexing agents on the properties of the microcapsules and extn. rate were studied. Capsules of a diam. <0.800 mm show little external resistance to mass transfer. The main resistance to mass transfer of the pesticides/herbicides resided in the hydrogel membrane composed of crosslinked alginate/polyacrylamide. Removal of divalent cations from the membrane by the addn. of citrate, resulted in a 50% increase in the mass transfer coeff., probably as a result of solubilization and exo-diffusion of alginate. [on SciFinder (R)]