Commutability Assessment of Processed Human Plasma Samples for Normetanephrine and Metanephrine Measurements Based on the Candidate Reference Measurement Procedure

Abstract

Background To identify candidate external quality assessment (EQA) materials for normetanephrine and metanephrine measurements, we assessed the commutability of eight processed human plasma samples. The agreement between routine assays and the candidate reference measurement procedure (cRMP) was also evaluated. Methods Fifty-three clinical samples and eight processed plasma samples were prepared. The processed samples included pooled and individual plasma samples spiked with pure normetanephrine and metanephrine and non-spiked pooled and individual plasma samples. The clinical and processed samples were subjected to four routine isotope dilution tandem mass spectrometry assays and cRMP. Commutability was assessed based on two approaches recommended by the CLSI and International Federation of Clinical Chemistry (IFCC). Passing–Bablok regression and Bland–Altman analysis were used to evaluate the agreement between the routine assays and cRMP. Results The commutability results of the CLSI approach were better than those of the IFCC approach. For the CLSI approach, spiked individual plasma samples and spiked high-concentration pooled plasma samples were commutable for all routine assays for both analytes. The non-spiked pooled plasma sample was commutable for two out of four routine assays for metanephrine and three out of four routine assays for normetanephrine. The agreement between the routine assays and the cRMP was satisfactory, except for one routine assay showing significant bias. Conclusions High-concentration spiked pooled plasma samples and spiked individual plasma samples are candidate EQA materials for normetanephrine and metanephrine measurements.

Simultaneous Measurement and Distribution Analysis of Urinary Nicotine, Cotinine, Trans-3′-Hydroxycotinine, Nornicotine, Anabasine, and Total Nicotine Equivalents in a Large Korean Population

“…To determine precision and accuracy, four levels of spiking pooled urine with working solutions of each biomarker (2, 20, 100, and 1000 ng/mL for nicotine, nornicotine, and anabasine; 5, 50, 250, and 2500 ng/mL for cotinine; and 10, 100, 500, and 5000 ng/mL for 3-OH cotinine) were prepared. Our method was validated according to the standard procedure and guidelines [35][36][37][38][39]. The analytical performance of our measurement system is summarized in Supplementary Table S4.…”