To assess worker isocyanate exposures in a variety of processes involving t
he manufacture and use of surface coatings, polyurethane foams, adhesives,
resins, elastomers, binders, and sealants, it is important to be able to me
asure airborne reactive isocyanate-containing compounds. Choosing the corre
ct methodology can be difficult. Isocyanate species, including monomers, pr
epolymers, oligomers, and polyisocyanates, are capable of producing irritat
ion to the skin, eyes, mucous membranes, and respiratory tract. The most co
mmon adverse health effect is respiratory sensitization, and to a lesser ex
tent dermal sensitization and hypersensitivity pneumonitis. Furthermore, is
ocyanate species formed during polyurethane production or thermal degradati
on may also produce adverse health effects. Isocyanate measurement is compl
icated by the fact that isocyanates may be in the form of vapors or aerosol
s of various particle size; the species of interest are reactive and theref
ore unstable; few pure analytical standards exist; and high analytical sens
itivity is needed. There are numerous points in the sampling and analytical
procedures at which errors can be introduced. The factors to be considered
for selecting the most appropriate methodology for a given workplace inclu
de collection, derivatization, sample preparation, separation, identificati
on, and quantification. This article discusses these factors in detail and
presents a summary of method selection criteria based on the isocyanate spe
cies, its physical state, particle size, cure rate, and other factors.