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Abstract
A new liquid chromatographic method with increased sensitivity has been developed for the determination of isocyanates common in industrial environments. The isocyanates are converted to stable urea derivatives by reaction with 9-(N-methylaminomethyl)-anthracene. These derivatives were analyzed using high performance liquid chromatography on a bonded octadecylsilyl phase using isocratic elution with acetonitrile/water and detected either by a UV or a fluorescence detector. The method was applied to toluene 2, 4- and 2, 6-diisocyanate (2, 4- and 2, 6-TDI), hexamethylene diisocyanate (HDI) and 4, 4-diphenylmethane diisocyanate (MDI).
The influence of various salts on the retention of the reagent amine was studied, as well as the separation of the urea derivatives on different C18-phases. The detection limit is about 1 · 10−4 mg/m3 for the isocyanates investigated, using either UV or fluorescence detection. This means that the new method is ten to twenty times more sensitive than the previously described reversed phase LC method, which utilized N-4-nitrobenzyl-N-n-propylamine as reagent.
