Correlation between Urine N-Terminal Telopeptide and Fourier Transform Infrared Spectroscopy Parameters: A Preliminary Study

Table 1

Summary of FTIR parameters.

Parameter	Abbreviation	Definition	Validation
Mineral-to-matrix ratio	Min/Mat	Area of phosphate (916 to 1180 cm^−1) band/area of amide I (1596 to 1712 cm^−1) band	Bone mineral content, correlated to ash weight
Carbonate-to-phosphate ratio	C/P	Area of the carbonate (852 to 890 cm^−1) band/area of the phosphate (916 to 1180 cm^−1) band	The level of carbonate substitution in the hydroxyapatite (HA) crystal
Crystallinity	XST	Intensity ratio of subbands at 1030/1020 cm^−1	Mineral crystal size and perfection as determined by X-ray diffraction
Collagen cross link	XLR	Intensity ratio of amide I subbands at 1660/1690 cm^−1	Collagen cross-link network maturity, ratio of mature and immature collagen crosslinks
Acid phosphate substitution	HPO4	Intensity ratio of subband at 1128/1096 cm^−1	The substitution of ions into hydroxyapatite lattice, characteristics of younger mineral