Appearance crystals or crystalline powder Specific rotation[α]20/D (C=1 in NaOH) +25.8° to +27.0° Ammonium (NH4) Not more than 0.02% Sulfate (SO4) Not more than 0.020% Heavy metal(Pb) Not more than 10ppm Loss on drying Not more than 0.50% Residue on ignition(sulfated) Not more than 0.20% Assay 98.5 to101.0% pH 2.0 to 3.5