Incorporation of foreign ions onto a biomineral surface as well as removal from it of native (physiological) ions during deproteination procedures, are discussed in view of surface design of orthopaedic implants serving as drug delivery carriers. Surface properties of bone-derived apatites, purified at low temperature in non-aqueous medium, and of several commercial samples are examined via XPS technique. It has been demonstrated that, in spite of the fact that the initial bone demineralized matrix is derived from the same bovine bone, different deproteination procedures lead to different surface properties. Correlation between carbon 1s deconvoluted peak and the percentage of the residual organic fraction on the bone-derived apatites’ surface at different stages of purification has been established.