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Licensed Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

Analytical performance and method comparison study of the total homocysteine fluorescence polarization immunoassay (FPIA) on the AxSYM analyzer

Silvia Lonati, Cristina Novembrino, Silvia Ippolito, Roberto Accinni, Claudio Galli, Hugo Troonen, Jonica Campolo, Cinzia Della Noce, Giovanna Lunghi and Fabrizia Bamonti Catena


A fluorescence polarization immunoassay (FPIA) has been commercially released for routine large-scale testing of total homocysteine (tHcy) on the AxSYM analyzer. We evaluated the analytical performance of the AxSYM tHcy FPIA and compared it with the well established high-performance liquid chromatography (HPLC) and IMx tHcy FPIA methods. Homocysteine concentrations were measured by AxSYM and IMx tHcy FPIA and by a rapid isocratic HPLC method with fluorescence detection. Coefficient of variation (CV) of total imprecision for AxSYM tHcy was ≤5%, mean dilution recovery 102%, analytical sensitivity 0.70 μmol/l and linearity was good up to 1:8 dilution. Spearman rank correlations, rho, were 0.83 (p<0.0001) for AxSYM vs. HPLC, 0.97 (p<0.0001) for AxSYM vs. IMx and 0.83 (p <0.0001) for IMx vs. HPLC. Passing and Bablok regression Y-intercepts and slopes were: 2.944/0.937 (AxSYM vs. HPLC), −0.367/1.142 (AxSYM vs. IMx) and 2.632/0.805 (IMx vs. HPLC). Corresponding mean differences (AxSYM-Comparison Assay) recorded over a 5–50 μmol/l measured range were 1.80, −0.73 and 2.53 μmol/l. AxSYM tHcy FPIA's first rate precision, supported by the complete automation of the AxSYM analyzer, makes it fit for routine use and suitable for laboratories requiring homocysteine high-throughput testing capabilities.

Published Online: 2005-6-1
Published in Print: 2004-2-18

Copyright © 2004 by Walter de Gruyter GmbH & Co. KG

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