Whole blood selenium determination by inductively coupled plasma mass spectrometry

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 8 h fast from healthy adults (76% females) with ages between 19 and 64 yr. Whole blood aliquots (1 mL) in acid washed cryogenic vials were stored at -70 degrees C until analysis. Results: The method passed the matrix effect, interference (except for Gd), and carryover tests. The method had a linear range of 0.2-7.1 mu mol/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 0.1 mu mol/L, a standard error of estimate of 0.1 mu mol/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 2.2-3.51.1 mu mol/L. Conclusions: This whole blood Se ICP-MS methodology is sensitive and acceptable for patient testing. (C) 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.