INCOMPLETE TRAPPING IN SUPPORTED LIQUID MEMBRANE EXTRACTION WITH A STAGNANT ACCEPTOR FOR WEAK BASES

Supported liquid membrane extraction is a powerful analytical methodol ogy for continuous extraction and enrichment of ionizable organic poll utants from aqueous environmental samples. Sample rrorkup with this te chnique can be hampered by low enrichment factors due to incomplete tr apping in the stagnant acceptor solution for weak basic compounds. The different parameters, such as acceptor pH and ionic strength of both the donor and acceptor solutions, related to this problem were studied theoretically and experimentally, A simple equation for the maximum e nrichment factor was developed. Results showed that the ionic strength s of the two aqueous phases in the system have an effect on the maximu m enrichment factor, which can be increased by increasing the ionic st rength of the donor phase. For chloro-s-triazines, a satisfactory agre ement was obtained between the experimental measurements and theoretic al estimations. This study defines the practical analytical applicatio ns and limitations of the system where the analytes are partially ioni zed in the acceptor solution.