Indirect determination of fluorides by the EDTA titration of samarium.
Fluorides are determined by the back-titration of excess of samarium with EDTA to the canary yellow end-point of Methylthymol Blue. The fluoride is precipitated and digested in a solution buffered at pH 2.5-3.0 with monochloroacetate buffer. After digestion, the pH is adjusted to 5.6-5.8 with pyridine and the excess of samarium is back-titrated in the presence of the precipitate, for samples with small quantities of fluoride. The procedure was used to analyse simple fluorides, fluoroborates and some other fluoro-complexes.
Combs
H F
HF
IIT Research Institute Chicago, Illinois 60616, U.S.A.
Grove
E L
EL