The impact of sample preparation on the elemental composition of soft tissues assessed by laser ablation ICP-MS

Abstract

Selected procedures of soft biological sample stabilization for analytical and medical diagnosis purposes (oven drying, short freeze drying and long freeze drying) were compared in terms of their suitability for elemental analysis by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The study was performed on model samples (chicken liver). Biologically important elements, such as Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Cu, Zn and Sr, were taken into account and subjected to statistical analysis (Single Factor Analysis of Variance and Duncan's post hoc-test). It was found out that freeze drying (but not oven drying) reduced the content of the elements Mg, Ca, Mn, Cu, Zn, Sr, P, and S; while the content of typical blood electrolytes (Na, Cl, and K) enhanced in the same samples. The evaluation of sample preparation processes was performed for ICP-MS bulk analysis of tissues, prepared with and without sample homogenization. Significant loss of Mn, Cu and Zn after freeze drying was confirmed while no effect (or a barely opposite effect compared to LA-ICP-MS analysis) was observed for blood electrolytes (Na and K), which indicates specific surface enrichment. Based on the results described in this work it was established that any water removal may induce changes in the primary elemental composition of soft tissues even if it allows their physical stabilization.