Abstract
Several solvent-free samplers for 4,4′-diphenylmethane diisocyanate (MDI) were evaluated in the field. The sampling systems used were: glass fiber filters, cellulose acetate filters, XAD-2 and natural sponge impregnated with 9-(N-methylaminomethyl)anthracene (MAMA), glass fiber filters impregnated with N-p-nitrobenzyl-N-n-propylamine (NBPA), and unimpregnated glass fiber and cellulose acetate filters which were subsequently treated with reagent solution. The samples were solvent-desorbed and analyzed by high performance liquid chromatography (HPLC). Three different liquid absorber sampling methods were also evaluated in the field: one with MAMA in toluene, another using NBPA in toluene, and the third using DMF-HCL as absorbing solution with subsequent derivatization with N-1-naphthylethylenediamine. Laboratory experiments show that all solvent-free methods investigated effectively trap MDI in the gas phase and also as an aerosol. The results from the field sampling are quite contrary to those from the laboratory experiments. The collection efficiency of all solvent-free samplers investigated is low as compared with the simultaneously used liquid absorbers. The results show that MDI is not generated as a simple MDI aerosol or as a gas in the common types of polyurethane production investigated in this study. A more complex MDI-matrix should be looked for.