The Microdetermination of Fluoride in Vegetation

Abstract

This paper describes a micro method for the determination of the fluoride content of plant materials, particularly the leaves. The samples are dried and ground to a fine powder. Fifty milligram samples are burned in oxygen in 250-ml separatory funnels or in 300-ml Erienmeyer flasks. The gaseous products of the combustion are absorbed in 0.1 N NaOH in the closed funnel or flask and transferred to a small covered plastic dish in which the fluoride is diffused to tiny droplets of 3N sodium hydroxide solution distributed over the lower side of a tight fitting cover. The diffused fluoride is dissolved in water and determined colori-metrically by the SPADNS reagent.