General description This certified reference material (CRM) is produced and certified in accordance with ISO/IEC 17025 and ISO Guide 34. This CRM is traceable to NIST- SRM.Certified content by quantitative NMR incl. uncertainty and expiry are given in the certificate.Download your certificate at: http://www.sigma-aldrich.com. 法律信息 TraceCERT 注册商标 Sigma-Aldrich Co. LLC