The determination of total fluoride in air by using a microdiffusion technique

Abstract

A method is described for the determination of total fluoride, in the form of dust, fume or vapour, in industrial atmospheres; it is applicable over a wide range of fluoride concentrations. After collection on an alkali-impregnated filter-paper, the fluoride is released specifically in a microdiffusion vessel and trapped by an alkaline coating on the inside of the lid of the vessel. The alkali is quantitatively transferred to a standard flask and the fluoride determined spectrophotometrically or visually with the lanthanum-alizarin fluorine blue reagent. The apparatus used is simple and the manipulation time required is less than 30 minutes per sample, although the microdiffusion stage requires a minimum of 16 hours (overnight) for completion.