Immobilized cholinesterase to detect airborne concentrations of hexamethylene diisocyanate (HDI)

A sensitive personal passive dosimeter, based on an enzymatic reaction, was developed to monitor exposure to airborne concentrations of hexamethylene diisocyanate (HDI), used in the production of polyurethanes. Dosimeters were prepared by adsorption of butyryl- or acetylcholinesterase on sheets of polystyrene. Exposure of enzyme-coated strips to vapors of isocyanates demonstrated their great sensitivity to HDI. Dosimeters detected workplace exposure levels of 5 ppb (NIOSH recommended threshold limit value) within 12 min. Dosimeters responded to higher concentrations of toluene diisocyanate (TDI). Interference by TDI and other anticholinesterase agents is unlikely as they would not be expected to be present in the same industrial workplace.