For best results, it is recommended to use the solution within 1 hour. Long term storage of the solution has not been evaluated. A prepared BCIP/NBT solution is available under product number B6404. This product is prepared in Tris buffer and may be stored at room temperature. See the links below for the product datasheets for each item.
B5655 Tablets
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/403/473/b5655dat.pdf
B6404 Premixed Solution
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/116/719/b6404bul.pdf