Lab grade isopropyl that I have seen is ~100% in the MSDS not accounting for the denaturing products, but certainly doesn't contain benzalkonium chloride.
I suspect OP is not telling the complete story, and actually used some type of lab grade sanitizing solution for cleaning surfaces, contact lenses, or hands. Something like Sterillium.
Iso doesn't need benzalkonium chloride to be denatured, as it is toxic all on its own. Iso is sometimes added to ethanol to denature it.
BC is sometimes added as a bitterant to keep alcoholics from drinking it anyway.