The ion‐exchange behaviors of succinic, malic and tartaric acids on Amberlite resins are evaluated. Retention and detector response data on silyl derivatives of several organic acids are presented. A procedure for the purification of grape juice by use of ion‐exchange resins prior to gas chromatography is described. The malic and tartaric acid contents (g/100 ml juice) respectively, of commercially acceptable grapes were found to be: Thompson Seedless 0.25, 0.90; Cardinal 0.31, 0.91; Beauty Seedless 0.19, 0.62; Perlette 0.26, 0.97; Exotic 0.27, 0.36; and Robin 0.41, 0