?maximum limit of impurities: Acidity or alkalinity: passes test Insoluble matter in C8H10: passes test Darkened substances by H2SO4: passes test Residue on ignition: 0.05 % Sulfur compounds: passes test Sulfate (SO4): 0.015% Reaction: passes test Residual solvents (Ph.Eur/USP): passes test Polycyclic aromatic hydrocarbons: passes test