A Comparison of Simple Analytical Methods for Determination of Fluoride in Microlitre-Volume Plasma Samples

F. Vida Zohoori, Anne Maguire, E. Angeles Martinez-Mier, Marília Afonso Rabelo Buzalaf, Roy Sanderson, George J. Eckert

Research output: Contribution to journalArticle


The aim was to compare potential methods for fluoride analysis in microlitre-volume plasma samples containing nano-gram amounts of fluoride. Methods: A group of 4 laboratories analysed a set of standardised biological samples as well as plasma to determine fluoride concentration using 3 methods. In Phase-1, fluoride analysis was carried out using the established hexamethyldisiloxane (HMDS)-diffusion method (1 mL-aliquot/analysis) to obtain preliminary measurement of agreement between the laboratories. In Phase-2, the laboratories analysed the same samples using a micro-diffusion method and known-addition technique with 200 μL-aliquot/analysis. Coefficients of Variation (CVs) and intra-class correlation coefficients (ICCs) were estimated using analysis of variance to evaluate the amount of variation within- and between-laboratories. Based on the results of the Phase-2 analysis, 20 human plasma samples were analysed and compared using the HMDS-diffusion method and known-addition technique in Phase-3. Results: Comparison of Phase-1 results showed no statistically significant difference among the laboratories for the overall data set. The mean between- and within-laboratory CVs and ICCs were < 0.13 and ≥0.99, respectively, indicating very low variability and excellent reliability. In Phase-2, the overall results for between-laboratory variability showed a poor CV (1.16) and ICC (0.44) for the micro-diffusion method, whereas with the known-addition technique the corresponding values were 0.49 and 0.83. Phase-3 results showed no statistically significant difference in fluoride concentrations of the plasma samples measured with HMDS-diffusion method and known- addition technique, with a mean (SE) difference of 0.002 (0.003) μg/mL. In conclusion, the known-addition technique could be a suitable alternative for the measurement of fluoride in plasma with microlitre-volume samples.

Original languageEnglish (US)
Pages (from-to)275-283
Number of pages9
JournalCaries research
Issue number3
StatePublished - Apr 1 2019


  • Fluoride
  • Method
  • Microlitre-volume
  • Plasma

ASJC Scopus subject areas

  • Dentistry(all)

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