PH-DEPENDENCE OF THE DISTRIBUTION COEFFICIENTS OF MONOMERIC OXO ANIONS OF PHOSPHORUS IN GEL CHROMATOGRAPHY WITH TIGHTLY CROSS-LINKED GELS

Sodium phosphinate, sodium phosphonate and potassium dihydrogen orthophosphate were chromatographed on a Sephadex G-10, G-15 or G-25 column with six kinds of eluents containing different alkali metal halides at various pH values. The distribution coefficient (Kd) on a tightly cross-linked gel column varies significantly depending on the pH of the eluent and is effectively insensitive to the kind of the eluent used. The pH profile of the Kd value is characteristic of the corresponding oxo acid of phosphorus and resembles closely its pH titration curve. The pH dependence of the Kd value of the oxo anion is discussed in terms of the distribution of the species in different dissociation states, which depends on the pH of the eluent. © 1979.