Fig. 5. (a) Effect of salt addition. Conditions: 300 μL 1-dodecanol as extraction solvent, 300 μL acetonitrile as dispersive solvent, 0.02 mmol L⁻¹ CTAB, 0.1 g (1.0% w/v) salt, vortex at 3200 rpm for 40 s. (b) Effect of amount of salt. Conditions: as described in (a) except amounts of Na₂SO₄ were varied.