Figure 6.

ToF-SIMS data from strontium-containing mineralized collagen tapes. (a) Linear dependence of Sr⁺/(Sr⁺ + Ca⁺) from Sr²⁺ content of standard tapes. Linear fit and linear equation are shown. (b) Three-dimensional rendered plots of Ca⁺ and Sr⁺ signal of a strontium-containing mineralized collagen tape (exemplarily 3 wt% strontium substitution), which served as standard for Sr²⁺ quantification in bone. A $1\hspace{0.17em}\mathrm{keV}\hspace{0.17em}{\mathrm{O}}_2^{+}$ beam was used for sputtering; analysis was carried out with $25\hspace{0.17em}\mathrm{keV}\hspace{0.17em}{\mathrm{Bi}}_3^{+}$ as primary ion species. Ca⁺ and Sr⁺ are distributed homogeneously within the material.