Objective: To develop a sensitive method for accurately measuring whole blood selenium and determining an appropriate reference interval for the local Cleveland population.
Design and methods: The assay was developed and validated on an inductively coupled plasma mass spectrometry (ICP-MS) with a collision cell. Whole blood trace element free EDTA tubes were used to collect samples for the reference interval study (n=50). Samples were collected after at least 8h fast from healthy adults (76% females) with ages between 19 and 64yr. Whole blood aliquots (1mL) in acid washed cryogenic vials were stored at -70°C until analysis.
Results: The method passed the matrix effect, interference (except for Gd), and carryover tests. The method had a linear range of 0.2-7.1μmol/L with accuracies of 87.1-118.1%. The total assay imprecision (CV) was <2.5% across the concentration levels tested. Comparison to another ICP-MS assay offered by an independent clinical lab yielded a Deming regression with a slope of 0.98, an intercept of 0.1μmol/L, a standard error of estimate of 0.1μmol/L, a correlation coefficient of 0.9846, and an average difference of 0.8%. The whole blood Se reference interval using a transformed parametric method was 2.2-3.5μmol/L.
Conclusions: This whole blood Se ICP-MS methodology is sensitive and acceptable for patient testing.
Keywords: ICP-MS; Reference interval; Selenium; Whole blood.
Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.