Why this range? The upper limit exceeding 100% accounts for chromatographic precision and the presence of closely related, non-harmful isomers, but it strictly excludes impurities.
Procedure: Dissolve about 50 mg of Vitamin K3, accurately weighed, in 75 mL of glacial acetic acid in a 250-mL flask. Add 25 mL of hydrochloric acid and 2 g of zinc powder. Pass a stream of carbon dioxide through the solution to exclude air, then heat on a steam bath for 15 minutes. Cool rapidly to room temperature, and titrate with 0.1 N ceric sulfate VS, using 0.15 mL of 1,10-phenanthroline indicator. Perform a blank determination. Each mL of 0.1 N ceric sulfate is equivalent to 8.81 mg of C₁₁H₈O₂. vitamin k3 usp monograph
Unlike the naturally occurring phylloquinone (K1) or menaquinone (K2), menadione is a synthetic, fat-soluble naphthoquinone lacking the phytyl or multiprenyl side chain. This structural difference grants it high reactivity but also necessitates stringent quality control. The USP monograph for Vitamin K3 covers menadione intended for use as an active pharmaceutical ingredient (API) or as a precursor for water-soluble bisulfite derivatives (e.g., Menadione Sodium Bisulfite). Why this range