Quality control
Endotoxin testing: what it catches and what it misses
LAL finds soluble Gram-negative endotoxin down to picogram levels. It says nothing about sterility, fungi, solvents, or anything alive.
Quality control
Salt and leftover solvent: the part of the bottle nobody counts
Counterions, water, and leftover solvent make up the rest of the powder. Three separate methods are needed to measure them, and HPLC is not one.