USP Reference Standards are specified for use in conducting official USP–NF tests and assays. USP also provides Reference Standards specified in the Food Chemicals Codex as well as authentic substances—high-quality chemical samples—as a service to analytical, clinical, pharmaceutical and research laboratories. To confirm accuracy and reproducibility, USP Reference Standards are rigorously tested and evaluated by multiple independent laboratories including USP, commercial, regulatory, and academic labs. USP also provide publicly available, official documentary standards for pharmaceutical ingredients in the USP–NF that link directly with our primary reference standards.

Entecavir System Suitability Mixture: This is a mixture containing entecavir 1-epimer (0.2%), entecavir (99.6%), 8-hydroxy entecavir (0.1%), and 8-methoxy entecavir (0.1%)