Identification of by-products in phenylisocyanate pre-column derivatization by thermospray liquid chromatography-mass spectrometry

Summary Thermospray liquid chromatography-mass spectrometry has been applied to the identification of by-products in precolumn derivatization by phenylisocyanate. These byproducts are eluted early in the same chromatographic region as the low molecular weight derivatives and were located by chromatographic analysis of a blank sample. Their identification would offer further qualitative information in the use of phenylisocyanate as a derivatizing agent. Five compounds resulted from the reaction of phenylisocyanate and the reaction medium were identified: two from a reaction between phenylisocyanate and methanol, two from the reaction between phenylisocyanate and water, and one from the polymerisation of phenylisocyanate.