Open AccessMeasuring zinc on the Roche cobas c502 analyzer—Validation, comparison, and pre‐analytic aspects
Author(s) -
Kraus Frank Bernhard,
LudwigKraus Beatrice
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22169
Subject(s) - zinc , detection limit , chromatography , analytical chemistry (journal) , spectrum analyzer , chemistry , mathematics , physics , organic chemistry , optics
Objectives Characterization of an in vitro diagnostic zinc assay ( LT ‐ SYS ) on a Roche cobas c502 analyzer and evaluation of the influence of pre‐analytic factors on zinc concentration measurements. Design and methods Imprecision, bias, linearity, limit of blank (LoB), and limit of detection (LoD) were established and method comparisons were performed based on the respective CLSI guidelines. The influence of time elapsed until analysis, the usage of a pneumatic tube delivery system ( PTDS ) and of special trace element sample tubes was evaluated as well. Results Estimates of imprecision ranged from 0.9% to 5.0% and bias was low with 1.3% and 1.5% deviation from target value. Linearity was met for the measuring range of 1.15‐34.7 μmol/L (7.51‐226.9 μg/dL), LoB and LoD were 0.17 μmol/L (1.11 μg/dL) and 0.73 μmol/L (4.77 μg/dL) respectively. The method comparison revealed an average deviation of 8.44% ( y =0.542+1.036x). Plasma samples had 7.3% higher zinc values than serum samples on the average. Zinc values of uncentrifuged serum and plasma samples increased 20% in 8 hours, while after centrifugation no significant increase could be detected. Usage of PTDS increased zinc values by 17% and usage of trace element sample tubes showed no advantage over normal ones. Conclusions The LT ‐ SYS zinc assay showed a fully acceptable performance with good degrees of imprecision and bias, no deviation from linearity and both a very low LoB and LoD. Samples for zinc analysis should be centrifuged timely and transport over PTDS should be avoided.