Modification of the Fluoride Determination

Factors Affecting the Determination of Fluoride in Water With Zirconium‐Alizarin

“…Reagents. These are: [11 sodium hydroxide pellets; [2] sulfuric acid, concentrated; [3] silver sulfate powder; and [4] phenolphthalein indicator. (D) is released and air pressure is applied to the tube (A).…”

“…Ratio mg fluoride;[2] for 1 hr readings when the phosphate does not exceed 0.20 mg, the error is not more than 0.007 mg fluoride; and[3] for 7-18 hr readings when the phosphate does not exceed 0.20 mg, the error is not more than 0.004 mg fluoride. If the concentration of phosphate in the sample aliquot exceeds these limits, the fluoride should be isolated by distillation.…”

“…T H E determination of fluoride by the zirconium-alizarin reaction has been studied by many investigators, beginning with De Boer. Among methods presently in general use are those of Sanchis (1), as modified by Scott (2), Lamar (3), and Megregian and Maier (4) . These are reported in Standard Methods (5).…”

Problems in Estimating Fluorides in Water

“…Gravimetric and volumetric methods are either unavailable or unsuitable for general use. The more successful procedures are colorimetric methods based on the bleaching action of the fluoride ion on certain organo-metallic complexes (1)(2)(3)(4)(5)(6)(7)(8)(9) . In particular, the action of 573 fluoride on a zirconium-alizarin lake has been intensively investigated and appears to be the best method available at the present time.…”

Modified Zirconium‐Alizarin Reagent for Determination of Fluoride in Water

“…The present standard method (1) using the zirconium-alizarin color reaction was developed by several investigators, beginning with DeBoer (2) and followed by Elvove (3), Sanchis (4-), and Scott (5,6). The evolution of the method has been characterized by changes in the reaction conditions and acid concentrations.…”