In this work a simple and inexpensive method to assess the concentration ratio of the labile and mineral-bound microelements of the bone tissue was developed. The approach is based on the separation of the components of bone tissue by their selective solubility with the subsequent determination of microelements with atomic absorption spectrometry. The total concentrations of Mg, Zn, Fe, Sr, Al, Cu, and Mn and the concentrations of these elements in aqueous solutions with pH 6.5, 10, and 12 after their ultrasonically activated interaction with the powder of dried bone were determined. Two quite different bone samples were analyzed: a cortical fragment of the femur of a mature healthy cow and the spongy part of a human femoral head affected by osteoporosis. Some common and individual features of the both type of bones in regard to the total concentrations and fractional distribution of microelements are discussed. The obtained concentrations of the "soluble" fractions of microelements were critically analyzed taking into account the possible reactions leading to new insoluble phases' formation in alkaline solutions. Based on the data obtained, the ability of elements to form labile fractions in the bone tissue could be arranged in the following descending series: Mg ≥ Zn > Al > Fe > Mn > Cu > Sr.
Keywords: Apatite; Atomic absorption spectrometry; Bone tissue; Concentration; Localization; Microelements; Selective solubility.