Turbulent flow chromatography in combination with HPLC-ICP-MS for high-throughput analysis of free, intact metal based drugs in biomedical samples

Abstract

We present an automated on-line extraction/chromatographic separation tool, which was successfully combined for the first time with ICP-MS detection in the context of metallodrug research. The method is based on turbulent flow chromatography (TFC) enabling efficient on-line separation of proteins from low molecular weight compounds, which can be retained on the TFC column, eluted for separation in a second dimension and detected via ICP-MS. Ex vivo incubations of a Pt(IV) candidate drug i.e. dichlorobis(ethylamine)bis((4-(2-propyloxy))-4-oxobutanoato)platinum(IV) (KP1873) with human serum albumin and human plasma showed the potential of the novel approach for studying metallodrug–protein interaction and metallodrug quantification, both key issues in (pre)clinical studies. Efficient on-line protein separation and retention for the Pt(IV) candidate drug was found by sulfur and platinum detection, respectively. An excellent mass balance for the TFC separation was assessed with column recoveries for HSA and the studied Pt(IV) drug of 110 ± 12% and 101 ± 2% showing the completeness of protein removal. As postulated, the drug did not show interaction with human serum albumin. However, incubation in human plasma led to the decrease of Pt retained on the TFC, implying the formation of either a free polar metabolite or a metabolite with a high affinity to plasma proteins. On-line TFCxHPLC-ICP-MS of the drug retained via TFC allowed the separation of the free, intact drug and a minor impurity or degradation product.