Chemical Structural Analysis of Bone by Spectroscopy - Vibrational Spectroscopy for Tissue Analysis - page 195

the peaks present due to the carbonate group of the in cm −1 (CO:- stretching
mode) and 1036 cm −1 (CO:- bending mode) also remained unchanged. The
difference in the spectra from the fresh and deproteinated bone can be seen
in Figures 7.1 and 7.2.
Hydroxyapatite is an intense Raman scatterer, which is indicated by the
exceptional signal-to-noise ratio. The values of the observed frequencies
for hydroxyapatite are tabulated in Table 7.1 and the spectrum is given in
Figure 7.3. A sharp but weak band at 952 cm −1 was attributed to a symmetric
P=O stretching mode on the basis of previous conventional Raman studies
of solid and aqueous phosphate [19-21]. The broad bands present at 774 and
690 cm −1 were assigned to an asymmetric P=O stretching mode on the basis of
comparison with the spectrum of calcium phosphate. The correlation between
the spectra of bone tissue and that of synthetic hydroxyapatite was only pres-
ent in the shared peak at 952 cm −1 of symmetric P=O (Figure 7.3 and Table 7.1).
The hydroxyapatite spectrum was dominated by the asymmetric P=O bands,
whereas the spectra of bone samples were dominated by the intense symmetric
P=O bands.

Deproteinated Sheep Bone

Deproteinated Human Bone

Synthetic Hydroxyapatite

3300 2950 2600 2250 1900 1550 1200 850 500 150

Wavenumber

Figure 7.3
Raman spectra demonstrating the differences between the synthetic hydroxyapatite, deprotein-
ated human, and sheep bones. (With permission.)