Abstract
Fluoride in water samples of given fluoride concentrations has been determined based on the “JIS K 0102 (34.1)” method. The following two problems have been found: 1) near the lower limit of the concentration range in this method, an error of about +25% occurs; 2) neither the available period nor the manner of storing the lanthanum-Alizarine complexone solution is described. The following two proposals have been made for dealing with the above two problems: 1) the value of the lower limit for the determination of fluoride should be raised; 2) the complexone solution remains stable for about 40 days when the solution is stored in a brown bottle in a dark and cool place.
