Commodity:Guanine CAS#:73-40-5 Molecular Formula: C5H5N5O Structural Formula: Uses: Intermediate of acyclovirpenciclovir, guaciclovir, famciclovir. Specifications: Item Standard Appearance White powder Identification IR Assay(HPLC) e99.0% Loss of drying d0.5% Residue on ignition d0.1% Heavy metal d10ppm Particle size(100 Mesh) e95%