Evaluation of nonisotopic binding assays for measuring vitamin B 12 and folate in serum

Abstract

We report the evaluation of the microparticle enzyme immunoassay (MEIA) for estimating vitamin B 12 and the ion capture (IC) assay for estimating folate in serum. The essays were performed with the Abbott IMx analyzer. Intra-assay coefficients of variation were from 3.4% to 8.0% for vitamin B 12 and from 1.5% to 4.2% for folate, respectively. Interassay coefficients of variation ranged from 6.3% to 8.8% for vitamin B 12 and from 3.9% to 11.3% for folate, respectively. Linearity was satisfactory, with an analytical recovery of 119 ± 4% for vitamin B 12 and 95 ± 8% for folate. The detection limit was 56.2 pmol/l for vitamin B 12 and 1.9 nmol/l for folate. Results of these assays correlated well with those from the cloned enzyme donor immunoassay (CEDIA), our current routine method: r = 0.97 for vitamin B 12 ( n = 47) and r = 0.97 for folate ( n = 50). The MEIA and the IC assay were easy to perform with the IMx analyzer.