Post-digestion stabilization of osmium enables quantification by ICP-MS in cell culture and tissue

Abstract

An orally active osmium anticancer compound was reliably quantified in the organs of treated mice by inductively coupled plasma-mass spectrometry (ICP-MS) by adding a stabilizing solution consisting of ascorbic acid, thiourea and EDTA during sample preparation and avoiding oxidizing conditions. The limits of detection (LOD) and quantification (LOQ) of ¹⁸⁹Os were determined in liver tissue to be 0.02 and 0.075 μg kg⁻¹, respectively. In spiked liver tissue, the internal precision showed a relative standard deviation (RSD) of 4%, a matrix recovery of 92% and a digestion recovery of 99%. A similar quantification protocol was developed for cellular accumulation studies in vitro. The cells were lysed with a non-oxidizing lysis buffer consisting of 150 mmol L⁻¹ NaCl, 1.0% Triton X-100, 0.1% SDS, and 50 mmol L⁻¹ Tris at pH 8.0 before adding the stabilizing solution. The osmium compound was compared with an isosteric ruthenium analogue and they displayed similar cellular accumulation and organ distribution profiles.