Dielectric determination of bound water of bone.

The dielectric consCa,rlt E' and dielectric loss E ' of human cortical bone have heen measured for frequencies of 1, 10, 50 and 100 kc and for hydrations ( h ) from 0 t o 65 mg-H,O,'g-bone. The absorption isotherm has also been detcrmined. Curves of E' and E" vs h are found to alter sharply at a particular value of the hydration, I t , . defining the ' critical hydration ' of bone. The quantity h,, ranges from 3 7 to 48 mg-H,O/g-bone, depending on the density of the sample. It is interpreted as the amount of water necesaary to occupy the primary absorption sites in hone, i.e., as the bound water of the system. The relationshlp nf h , with previously reported values of the bound water 111 hide collagen and synthetic hydroxyspatite is discussed.