Factors Parameters Forward Extraction   AOT 20 mM pH 7.0 Time 30 min Temperature 4°C Backward Extraction   Salt concentration 0.5, 1.0, 1.5 and 2 M pH 6.5, 7.0, 7.5, 8.0, 8.5 Time 1 hr Temperature 4°C No. of replicates = 3 No. of runs = 60

Table 1: Optimization of the backward extraction (changing pH and KCl concentration).