Application of a statistical method to counter-current distribution of acids and bases and their separation by discontinuous change of pH

✍ Scribed by Corrado Galeffi

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 450 KB
• Volume: 92
• Category: Article
• ISSN: 1873-3778
• DOI: 10.1016/s0021-9673(00)97183-8

✦ Synopsis

A statistical method is applied to the partition of an acid or a base between two phases in a counter-current apparatus. Four equations are obtained, depending on whether the mobile phase is organic or aqueous. These expressions correlate the number of transfers and the position of the distribution curve maximum with pH, dissociation constant (K&J and distribution constant (K,). It was found that two acids (or bases) with a K;Kdiss p roduct in a 1: 10m ratio are eluted with numbers of transfers in the same ratio, provided that the pH is constant. In contrast, at two pH values which differ by m they are eluted with an equal number of transfers. A partition method for separation is thus proposed in which the pH of the aqueous mobile phase changes discontinuously, decreasing for the bases and increasing for the acids. The theoretical distribution curve is calculated and two examples are given of the application of the method.