Determination of lead permanganometrically (Low’s method)
It has been shown that hydrochloric acid can be used for dissolving lead oxalate precipitates in the estimation of lead and also for the titration of the liberated oxalic acid with permanganate provided the concentration of the hydrochloric acid is not greater than 0·5 N. Employment of hydrochloric acid obviates the difficulties due to occlusion of oxalic acid in Low’s method and the complications in the permanganate titration arising out of the use of nitric acid. Quantitative precipitation of lead as oxalate does not require 60% concentration of acetic acid. Precipitation is complete even when 5–6% of this acid is present. The use of nitric acid in oxalic acid-permanganate titrations has been shown to be not permissible.