Abstract
MDI and PAPI are frequently substituted for TDI in commercial applications because of their low vapor pressures which decrease the hazard potential. TDI may be present as an impurity of only a few percent and still give rise to vapor levels above the TLV. A gas chromatographic method for determining TDI has been adapted for the measurement of TDI in MDI and PAPI. A weighed sample is dissolved in a known quantity of solvent and a 5-microliter aliquot is introduced into the chromatograph. The run is made isothermally on a 6-foot stainless-steel column packed with 10% DC 710 on Fluoropak. The TDI peak is eluted in about 5 minutes. Detailed operating conditions and techniques of sample preparation and injection are discussed.