Applicable to products having a water content between 0.01 % (m/m) and 0.5 % (m/m). Is supplemented by ISO 3700 and intended for reference purposes. Bases on addition of a cooled test portion to cooled dry pyridine containing 5 % of anhydous hydrogen fluoride. The apparatus for measuring the test portion and titration and the measuring vessel are shon in figures. Subsequent electrometric titration of the water with the Karl Fischer reagent.