Determination of phenol in poly(vinyl chloride)

There are strong indications that some poly(vinyl chloride) (PVC) plastics may contain phenol. This would be particularly harmful in the case of PVC used as a raw material for toys. An analytical method for determining phenol in PVC was therefore designed. The method is based on dissolving the whole sample in tetrahydrofuran and precipitating PVC by addition of water. After filtration the solution is ready for injection into an HPLC instrument. For quantitative analysis p-cresol is used as internal standard and it is added to the THF solution before precipitation. The method is applicable in the concentration range 50-3000 mg phenol/kg PVC. The detection limit is about 10 mg phenol/kg PVC but may be easily increased ten-fold by gentle removal of tetrahydrofuran from the sample solution and cleaning of the sample with C18 cartridge, which allows the injection of larger volumes and thus improves sensitivity. The method has been submitted for collaborative study in municipal laboratories in Finland.