Solubility product

Calcium phosphate ceramics are used, in part, as coatings on orthopedic implants. These materials are slowly absorbed in human tissue. In order to ensure the purity and consistency of calcium phosphate materials, it is advisable to determine the solubility product (K_SP). The K_SP is a material property that describes a chemical equilibrium between a solid substance and a solution of the same substance. The RMS Foundation offers a standardized procedure in which a sample is soaked in phosphoric acid for 60 days and the K_SP is subsequently determined based on the pH value and the Ca and P concentrations

Temperature-controlled incubator shaker IKA™ KS 4000i
Agilent 7700x ICP-MS
pH electrodes

What needs to be considered with these methods and samples?

We can test powders or coatings.
The minimum quantity is approx. 3 g
On request, we can also carry out parallel measurements on reference material (NIST).

Which products can be tested at the RMS?

The determination of the K_SP is useful for monitoring the purity and consistency of hydroxyapatite raw materials on recurring production batches, or to compare the purity of the material with a hydroxyapatite NIST reference material. Further information can be found here.