Supported liquid membrane extraction for sample work-up and preconcentration of methoxy-s-triazine herbicides in a flow system

A method for sample preparation of methoxy-s-triazine herbicides using supp orted liquid membrane extraction has been developed. The analytes were sele ctively extracted from the donor solution of pH 7.0 into a porous polytetra fluoroethylene (PTFE) membrane impregnated with di-n-hexyl ether. After dif fusion through the hydrophobic membrane the analytes were irreversibly trap ped in the acidic acceptor phase of pH 1.0. The donor waste was monitored f or estimating the amount of sample trapped at certain time intervals. Compa rison of the selectivity with solid-phase extraction has been performed. A low detection limit, ca. 15 ng/l, has been obtained with liquid membrane ex traction. (C) 1999 Elsevier Science B.V. All rights reserved.