Development of a HPLC method for the sensitive determination of carbonyl chloride in polycarbonate for food contact articles

A HPLC method was developed for the determination of residual carbonyl chloride in polycarbonates and other plastics packaging materials. The method is based on dissolution of polymer and simultaneous derivatization of the residual carbonyl chloride using 2-aminophenol solution as derivatization agent. The derivatization reaction is very rapid and gives a high yield of a stable carbonyl chloride derivative (2-benzoxazolinone) which was analysed using HPLC with UV-detection. The average recovery rates were satisfactory and the average detection limit of 0.2 ppm was found to be sufficiently suitable for the intended purpose, i.e. the control of a highest admissible level of 1 ppm in the food contact material. During the experimental work it was observed that the derivatization reagent 2-aminophenol reacts not only with carbonyl chloride but attacks also dissolved polymer or oligomers to yield the same derivative as breakdown product which can negatively influence the analytical result if no precaution means are taken. For this reason considerable optimisation work was made, to make the method suitable for being a sensitive and reliable method for determination of residual carbonyl chloride in food contact polymers.