Investigating the effects of chelating agents, surfactants and magnesium cations on the size of LPS aggregates in formulations causing low endotoxin recovery in limulus amebocyte lysate assays

generally inhibited the excipients' capacity to decrease aggregate size, most effectively in phosphate-containing samples. Despite these variations in size, the overall aggregate shape remained largely unchanged in all formulations. These findings suggest that LPS aggregate size or shape does not distinguish formulations causing LER; instead, factors such as the characteristics of the LPS aggregate surface in different formulations should be explored in the future.