A procedure for the routine determination of fluorine in potable waters containing iron, manganese, aluminum, and chlorine.

Abstract

DY THE first of the year 1952, 158 communities in thirty-three states were D fluoridating their water supplies.' It has been estimated that a total of 34 million people will be drinking fluoridated water by the end of 1952. Epidemiological studies have established that 1.0 to 1.2 parts per million of fluoride ion naturally occurring in communal water supplies reduces the incidence of tooth decay by 50 to 60 per cent without producing mottled enamel. Because mild dental fluorosis may occur at a slightly higher concentration of fluoride ion and maximum protection against caries may not be attained if the fluoride ion concentration is too low, it is of the utmost importance that the fluoride ion be supplied and maintained at the proper level in the communal water supply. Thus, the need for a simple, rapid, and accurate method for the routine determination of fluoride is apparent. The purpose of this article is to report a method for the routine determination of fluorine in potable waters which may contain various substances that interfere in the conventional Sanchis-Scott method2 of analysis. The procedure being presented, which is a modification of the Sanchis-Scott method, permits the determination of fluoride ion in potable waters containing iron, manganese, aluminum, and chloride, as well as the substances tolerated by the Sanchis-Scott method. The unmodified Sanchis-Scott method permits the presence of chloride, sulfate, alkalinity (expressed as CaCO3), and phosphate, all in micro quantities. The employment of this modified Sanchis-Scott method of analysis for routine control of fluoride in communal water supplies will circumvent the use of the more laborious and time-consuming distillation method for the separation of the fluoride from interfering ions.