Automated liquid membrane extraction and trace enrichment of triazine herbicides and their metabolites in environmental and biological samples

A selective liquid membrane extraction technique has been developed for enrichment of the s-Triazine herbicides and their common degradation products. The uncharged analyte molecules entering the donor channel diffuse through an organic solvent immobilized in a porous hydrophobic membrane. In the acceptor phase, a chemical ionization is facilitated so the diffused analyte molecules are irreversibly trapped, and thereby concentrated. The effect of addition of carrier molecules in the membrane liquid has been investigated, and trioctyl phosphine oxide (TOPO) was found to be the best. The analyte salting out effect was also studied by varying the concentration of sodium chloride in the extraction sample solution. The selectivity of the extraction methodology in surface water and urine samples has demonstrated the potential applications of the technique for enrichment of s-triazine herbicides and their metabolites in samples containing complex matrices.