EFFECT OF INITIAL PH ON HYDROLYSIS OF ALP HA-TRICALCIUM BIS(PHOSPHATE) IN SOLUBILIZED COLLAGEN SOLUTION

The hydrolyzed products of alpha-tricalcium bis(phosphate) (alpha-TCP) formed in solubilized collagen solution for several initial pH's (pH 4 to 8) at 30-degrees-C for 24h were investigated by X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), chemical ana lysis and so on. For initial pH4 the formation of calcium hydrogenphos phate dihydrate (DCPD) and for initial pH over 5 the formation of hydr oxyapatite (HAp) were detected by XRD. Further, it was found from the results of FT-IR that for initial pH 4 a small amount of HAp and octac alcium dihydrogen hexakis (phosphate) (OCP) were formed as hydrolyzed product, and for initial pH over 5 the formation of OCP were observed in addition to HAp. The formation of HAp was at the maximum for initia l pH 5, and the amount of HAp in hydrolyzed product obtained in 0.1 mo l dm-3 acetic acid-ammonia buff er solution with solubilized collagen was higher than that without collagen. Ca/P molar ratios of the produc ts calculated from the results of chemical analysis were varied from 1 .3 to 1.5, which were lower than that of stoichiometric hydroxyapatite (Ca/P=1.67). The processes of the hydrolysis of alpha-TCP, which were suggested by the chemical equations, were explained reasonably by the results of XRD, FT-IR and chemical analysis.