Thiamine EP Impurity H is a process-related impurity that is created during thiamine-based drug product synthesis. Chemically, it is known as Thiamine Thiocarbamate and has the molecular formula of C₁₄H₂₀N₄O₃S₂ with a molecular weight of 356.46. https://chemicea.com/blog-details/thiamine-ep-impurity-h-affect-drug-safety