Optimizing the performance of single-cell ICP-MS/MS for Fe and Zn determination in human umbilical vascular endothelial cells

[Display omitted] •Cell suspension influences the background in scICP-MS for Zn and Fe determinations in HUVEC cells.•Excellent stability and reproducibility by cell fixation with 10% paraformaldehyde.•Cell fixation with PFA does not affect the background signal.•Detection limits sufficiently low for Fe and Zn with enhanced accuracy using a 3 ms dwell time.•Serum albumin acts to regulate intracellular Zn uptake. Inductively coupled plasma-mass spectrometry operated in a single-cell mode (scICP-MS/MS) has emerged as a technique that allows measurement of metal concentration at the cellular level. The approach is made possible by the high sensitivity of modern instrumentation. However, specific applications may be limited by spectral and non-spectral interference that can occur due to the complexity of the matrix that requires to be analysed. As such, the success of this approach requires adequate sample preparation, allowing the stability of the cells to be preserved before introducing them into the plasma. In this context, a method was developed to measure Zn and Fe concentrations in individual human umbilical vein endothelial cells (HUVEC) using scICP-MS/MS. As a strategy, the suspension of HUVECs was prefixed with paraformaldehyde aiming to achieve experimental stability and repeatability without significantly affecting the background signal. Moreover, different dwell times (3, 5 and 10 ms) were assessed to optimize the instrumental parameters. As a result, the best performance for Zn and Fe measurement by scICP-MS/MS in terms of sensitivity and accuracy was obtained with the dwell time of 3 ms. To the best of our knowledge, the concentrations of Fe and Zn in fixed single endothelial cells has not been explored previously using scICP-MS. Here, the developed scICP-MS/MS method was successfully used to examine the influence of different culture conditions on Fe and Zn uptake in fixed single HUVEC cells.