In vitro evaluation of microdialysis–electrothermal vaporization inductively coupled plasma mass spectrometry hyphenation system for continuous monitoring of trace metal ions in simulated biological systems

Abstract

An on-line microdialysis sampling coupled with flow injection (FI) electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) hyphenation system has been developed for continuous monitoring of trace Zn, Cu, Mn and Pb ions in microdialysates, with good temporal resolution and high sensitivity. In order to achieve efficient removal of the salt matrix in the dialysate, the characteristics of three matrix modifiers, NH₄NO₃, NH₄H₂PO₄ and Pd, were evaluated. The influence of the temperature program on the separation efficiency and the analytical signals was also studied in this work. With microdialysis sampling, the temporal resolution for monitoring was limited by very low perfusion rate to 12 min. The detection limits were 2.20 μg L⁻¹ (Zn), 0.15 μg L⁻¹ (Cu), 1.13 μg L⁻¹ (Mn) and 3.13 μg L⁻¹ (Pb) and the stability precision (RSD at 10 μg L⁻¹ analyte ions) was <15% RSD. The performance of the proposed method was evaluated in vitro by monitoring step changes in the concentrations of analyte ions in the external microdialysis medium.