Abstract
Exploration of brain extracellular non-protein-bound/diffusible iron species remains an important issue in investigations of free radical biology and neurodegenerative diseases. In this study, a sample pretreatment scheme, involving poly(vinyl chloride)–packed minicolumn as a selective extraction device, was optimized in conjunction with microdialysis sampling and inductively coupled plasma mass spectrometry (ICP-MS) in cool-plasma mode for in vivo online monitoring of rat brain extracellular Fe(II) and Fe(III). After system’s optimization, the method’s applicability was verified through (i) spike analyses of offline-collected rat brain microdialysates, (ii) determination of the basal Fe(II) and Fe(III) concentrations of living rat brain extracellular fluids, and (iii) monitoring of the dynamic changes in the Fe(II) and Fe(III) concentrations in response to perfusion of a high-K+ medium. Furthermore, to enable speciation of trace iron in environmental samples, a stereolithographic 3D printer and acrylate-based resins were utilized to fabricate a demountable minicolunm to selectively extract Fe(II) and Fe(III) and facilitate their analyses in high-salt-content environmental samples by hyphenating to ICP-MS. After system’s optimization, the analyses of the reference materials 1643e, 1640a, CASS-4, and SLEW-3 as well as the spike analyses of those collected environmental samples were performed to confirm the method’s reliability. These two proposed sample pretreatment schemes, based on respectively using the PVC-packed minicolumn and the non-functionalization 3D-printed minicolumn, appear to have great practicality for the iron speciation in biological and environmental samples.