Mass spectra of molecular ions in the cathode sputtering of hydroxyapatite within argon glow discharges were studied experimentally and through mathematical simulation. The study was aimed at developing a highly sensitive technique for the determination of toxic and physiologically active elements in hydroxyapatite, used for medical purposes, by glow discharge mass spectrometry. Mass spectra were simulated employing the method developed previously for the calculation of molecular ion concentrations in glow discharge plasma and the computer program for its implementation. The effective equilibrium constants were refined for the formation–dissociation reactions of molecular ions during cathode sputtering of hydroxyapatite on a tantalum substrate. Comparison between the experimental and calculated mass spectra confirmed that the model was accurate. The study revealed molecular interferences in the mass range from ¹⁹F to ²³⁸U that were not adequately separated from the isotopes under study, thus reducing the analysis detection limit. The isotopes that were minimally affected by molecular interferences were chosen, and the resolution needed to achieve a detection limit of around 1 ppm for monoisotopic elements was calculated. To maintain a sufficiently high ionic current for nonconductive matrix isotopes (⁴⁴Ca, ³¹P), a previously improved design of the analytical cell with high-purity tantalum as a substrate was employed. Most of the studied elements can be determined within ppm-ppb limits employing mass spectrometers with a high resolution (≥9000) at half the peak height.

通过实验和数学模拟研究了氩辉光放电中羟基磷灰石阴极溅射中分子离子的质谱。该研究旨在开发一种高灵敏度技术，通过辉光放电质谱法测定医疗用羟基磷灰石中的有毒元素和生理活性元素。采用先前开发的计算辉光放电等离子体中分子离子浓度的方法及其实施的计算机程序来模拟质谱。对钽基板上羟基磷灰石阴极溅射过程中分子离子的形成-解离反应的有效平衡常数进行了细化。实验质谱与计算质谱的比较证实该模型是准确的。该研究揭示了质量范围从¹⁹ F 到²³⁸ U 的分子干扰，这些干扰没有与所研究的同位素充分分离，从而降低了分析检测限。选择受分子干扰影响最小的同位素，并计算单同位素元素达到约 1 ppm 检测限所需的分辨率。为了保持非导电基质同位素（⁴⁴ Ca、³¹ P）足够高的离子电流，采用了以前改进的分析池设计，以高纯度钽作为基质。大多数研究的元素可以使用半峰高高分辨率 (≥9000) 的质谱仪在 ppm-ppb 范围内测定。