Iron isotopic analysis of finger-prick and venous blood by multi-collector inductively coupled plasma-mass spectrometry after volumetric absorptive microsampling

Abstract

High-precision isotopic analysis of Fe in blood is currently assessed as a complementary approach to achieve a better understanding of human Fe metabolism and for diagnosis of diseases. Volumetric absorptive microsampling (VAMS) is a recently introduced technique that allows the straightforward collection of a well-defined volume of blood by dipping an absorbent polymeric tip into it. In this work, the use of VAMS was evaluated for high-precision isotopic analysis of whole blood Fe by multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). Fe concentrations in whole blood sampled using VAMS were determined by single-collector sector-field ICP-MS. A variety of solvents were evaluated for extraction of Fe from the VAMS-device (Mitra™). Fe was quantitatively extracted from the absorbent using 1 mL of Milli-Q water. The extracted material was subsequently subjected to acid digestion and to a miniaturized chromatographic procedure for isolation of Fe from the blood matrix. The Fe isotopic compositions and concentrations of paired finger-prick and venous blood samples collected at the same time from six individuals were compared. No significant differences were found between the two blood types. The proposed methodology significantly increases the sample throughput and facilitates sample acquisition for Fe isotopic analysis in clinical applications.