Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

Abstract

The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter’s Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

Infrared spectroscopic assessment of the inflammation-mediated osteoporosis (IMO) model applied to rabbit bone

“…In general, models of osteoporosis [44] and osteoporotic tissues in humans [45,46] are characterized by a decreased mineral/matrix ratio. No significant disparities ( p > 0.05) were observed between the two sex groups regarding the degree of mineralization, confirming previous studies [47] that are also related to the Ca/P ratio as a critical mineralization biomarker [48,49]. Trabecular bone apatite, represented by rib samples, shows decreased mineral deposited in the bone matrix in a highly significant manner ( p = 0.0002) compared to the compact sections.…”

Ca/P concentration ratio at different sites of normal and osteoporotic rabbit bones evaluated by Auger and energy dispersive X-ray spectroscopy

“…Ca LMM Auger transition is well defined at 280-290 eV, while peaks recognized at 90-110 eV and near 260 eV correspond to the P LMM and C KLL transitions, respectively. The carbon 1s peak is attributed to the carbonate apatitic environment of bone and not to beam-induced carbon contamination, which is generally not observed in ground homogenized materials [38]. Bone sections, however, usually sustain this effect, probably due to the evolution of a Ca-deficient carbonated apatitic phase at the surface and the grain boundaries of bone hydroxyapatite polycrystalline specimens [62].…”

“…Our research group was the first to utilize AES for the determination of Ca/P at different sites of bone [38] and this study is also implemented as a continuation to our previous one to further examine the mineral phase at different sites and in relation to osteoporosis. AES provides high spatial resolution and surface sensitivity, permitting measurements of elemental concentrations throughout a wide range of the periodic table (with the exception of H and He).…”

“…In vitro bone elemental analysis has been performed using synchrotron radiation micro-CT [20,21], neutron activation [22,23], X-ray diffraction [24], small-angle X-ray scattering [25,26], inductively coupled plasma optical emission spectroscopy (ICP-OES) combined with direct current argon arc plasma optical emission spectrometry (DCA ARC) [27], and chemical analysis [28]. Specifically related studies relying solely on spectroscopic methodologies include solid-state nuclear magnetic resonance (NMR) [29][30][31], X-ray fluorescence [32], TEM-EDX [33,34], SEM-EDX [35], and relevant surface analysis techniques such as X-ray photoelectron spectroscopy (XPS) [36,37] and AES [38].…”