Atomic Absorption Spectrophotometric and Ethylenediaminetetraacetate-Titration Methods for Calcium and Magnesium Determinations

Abstract

Ethylenediaminetetraacetate-titration and atomic absorption spectrophotometric methods were compared for determining Ca and Mg in solutions of known concentration and in subtropical forages. Concentrations of Ca and Mg in known solutions ranged from 0.68 to 13.59 ppm and 0.06 and 1.18 ppm, respectively. At this low level of concentration, the EDTA-titration method was not reliable for determining Mg. A high correlation was found for both the EDTA-titration and the atomic absorption methods for determining Ca and Mg in solutions of known concentration. Concentrations of Ca and Mg determined by atomic absorption varied less from known concentrations than were found with EDTA-titration method at concentrations used in the test solutions. The subtropical forage samples analyzed contained from 0.17 to 0.52% Ca and 0.11 to 0.31% Mg, respectively, on an oven-dried weight basis. Slightly, but not significantly, higher results for Ca and Mg were obtained by EDTA-titration than for those obtained by atomic absorption. Results obtained by the atomic absorption method agreed with known values of Ca and Mg, and the rapid and accurate analyses made possible by this method were important factors in its favor over the EDTA-titration for routine analyses. © 1969, American Dairy Science Association. All rights reserved.