The minimum protein content for this product is 1 mg/vial. It is best to review the lot specific Certificate of Analysis prior to reconstitution as the vial content may be slightly higher that 1mg. The product may then be reconsituted in water to the desired concentration. Please see the links below to review the product datasheet and to access the corresponding Certificate:
Product Datasheet
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/272/311/n8630pis-ms.pdf
Certificate of Analysis
https://www.sigmaaldrich.com/search