This product is not tested for purity. The testing includes the appearance, particle size, and identity confirmation by X-Ray Diffraction. Please see the link below to review a sample Certificate of Analysis: https://www.sigmaaldrich.com/certificates/sapfs/PROD/sap/certificate_pdfs/COFA/Q14/237965-100G0000226203.pdf
A highly purified version of the compound is available as product 449903. This material has a minimum purity specification of 99.99%. Please see the link below to review this product option:
https://www.sigmaaldrich.com/product/aldrich/449903