Transport of amino acids through organic liquid membranes. I. p-Aminobenzoic acid

The transport of p-aminobenzoic acid (PABA) through a liquid membrane (100 mL of chloroform in which 1 g of undecanoic acid has been dissolved) between two aqueous phases is discussed. The geometry of the system used induces an inequality of the contact surfaces between the two aqueous phases and the liquid membrane. The results obtained reveal the influence of the composition of the aqueous phases and the surface contact dimension upon the direction and intensity of the PABA transport. The result of the transport is PABA accumulation in the aqueous phase at alkaline pH. Experimental data allowed the delimitation of the optimum domain of composition of the two aqueous phases, assuring the maximum value of PABA transport. Some conclusions to be drawn from this work may also be extrapolated to biological membranes.