Abstract: A modified latent projection is proposed based on the characters of first in and first fixed feature of the titrative distributive coefficients of monoacids or monobases that have different pK. The single variant region is defined and the transfer vector is derived. Grey system which consists of two monoacids(or bases) mixtures can be ananyzed by this method.The pure titrative distributive coefficients and concentrations for p-chlorophenol and o-chlorophenol mixtures are obtained by using two-dimensional pHtitrative data and the modified latent projection.

Key words: Latent projection, Two-dimensional pH titration, Grey system