How is the concentration of 80% hydrazine hydrate calculated for industrial use?

How is the concentration of 80% hydrazine hydrate calculated for industrial use?
Hydrazine hydrate is typically traded at 24%, 40%, 55%, 80% and 100% concentrations, with 40-80% aqueous solutions dominating industrial applications. The 80% grade is the most common commercial form in China, used heavily in ADC foaming agents, boiler water deoxygenation, and pharmaceutical synthesis. Concentration calculations follow the standard formula c=1000ρw/M, where density and mass fraction determine molarity. Notably, hydrazine forms an azeotrope with water at roughly 69% hydrazine content under normal pressure, which complicates purification beyond that level. Buyers should verify actual assay values upon delivery, as density varies with temperature and impurities, affecting effective concentration and downstream dosing accuracy.