Even though they are rare, they can occur, and they are more related to the drug that is dissolved in BW
Peptide-specialist research suppliers that publish independent HPLC purity reports (at least 98% purity), mass spectrometry confirmation of the correct molecular weight (1815.1 Da), and endotoxin testing results are the most defensible sourcing choice for research use
Yang D, Yang Y, Zhou Y, Yu L, Wang R, Di B, et al
Bacteriostatic Water: A Comprehensive Understanding
Community references describe marking the puncture date on the vial label with a pharmacy-tape note or marker as a common practice to track the 28-day clock
The tripeptide binds copper with a dissociation constant in the nanomolar range, which is tight enough to compete with other copper-binding proteins in tissue