Determination of 3,3'-dichloro-4,4'-diaminodiphenylmethane in air

A simple gas chromatographic method is described for the analysis of 3,3'-dichloro-4,4'diaminodiphenylmethane (MOCA) in air. MOCA is quantitatively collected on a Gas-Chrom S tube and the solid sorbent is extracted with acetone. An aliquot sample of the extract is introduced directly into the gas chromatograph, using a microsyringe and the sample is chromatographed on a 1-ft.,silylated 10% Dexsil column. The peak area of MOCA is measured and related to the concentration via a calibration curve prepared with a constant volume of standards. The chloroanilines associated with MOCA cause no interference; however, interference can be expected from any compounds having a retention time identical to that of MOCA. As little as 0.002 mug of MOCA per mul of acetone can be detected by this method.