Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS). (22nd November 2019)

• Record Type: Journal Article
• Authors: Burdette, Carolyn Q; Camara, Johanna E; Nalin, Federica; Pritchett, Jeanita; Sander, Lane C; Carter, Graham D; Jones, Julia; Betz, Joseph M; Sempos, Christopher T; Wise, Stephen A
• Is Part Of: Journal of AOAC International. Volume 100:Number 5(2017)
• Page Start: 1277
• Page End: 1287
• Publication Date: 2019-11-22
• Subjects: Agricultural chemistry -- Periodicals; Food -- Analysis -- Periodicals; 543
• DOI: 10.5740/jaoacint.17-0306
• Languages: English
• ISSNs: 1060-3271

Abstract

Abstract: Until recently, the Vitamin D External Quality Assessment Scheme (DEQAS) assessed the performance of various assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] by using a consensus mean based on the all-laboratory trimmed mean (ALTM) of the approximately 1000 participants' results. Since October 2012, the National Institute of Standardsand Technology (NIST), as part of the Vitamin D Standardization Program, has participated in DEQAS by analyzing the quarterly serum sample sets using an isotope dilution LC-tandem MS (ID LC-MS/MS) reference measurement procedure to assign an accuracy-based target value for serum total 25(OH)D. NIST has analyzed90 DEQAS samples (18 exercises × 5 samples/exercise) to assign target values. The NIST-assigned values are compared with the ALTM and the biases assessed for various assays used by the participants, e.g., LC-MS/MS, HPLC, and several ligand-binding assays. The NIST-value assignment process and the resultsof the analyses of the 90 DEQAS samples are summarized. The absolute mean bias between the NIST-assignedvalues and the ALTM was 5.6%, with 10% of the samples having biases >10%. Benefits of the accuracy-based target values are presented, including for sample sets with high concentrations of 25(OH)D2 and 3-epi-25(OH)D3 .