Method for the determination of perfluorooctanoic acid in air samples using liquid chromatography with mass spectrometry

Perfluorooctanoic acid is a completely fluorinated carboxylic acid that is usually used in the ammonium salt form as a processing aid in the production of many fluoropolymers and fluoroelastomers. Ammonium perfluorooctanoate readily dissociates in water to give the ammonium and perfluorooctanoate ions. Peifluorooctanoate has been reported to be present in low levels in human serum in the United States and Europe. This study reports on the development and validation of a method for the determination of perfluorooctanoic acid in air samples. This method uses the Occupational Safety and Health Administration (OSHA) Versatile Sampler (OVS) with a nominal 0.3 mu m filter and polystyrene resin sorbent (XAD-2 or XAD-4)followed by determination of the perfluorooctanoate anion by liquid chromatography mass spectrometry. The method was validated in the range of 0.474 to 47.4 mu g/m(3) for a 480-L sample. Breakthrough studies showed samples could be collected at I L/min for 24 hours or at 15 L/min tip to 8 hours without breakthrough. Extract storage stability tests showed that sample extracts in methanol remain stable in glass autosampler vials for up to 13 days following initial injection. Perfluorooctanoic acid stability on OVS tubes was unaffected at both refrigerated and ambient temperatures. The overall average retention efficiency was 92.1% with a pooled RSD95 of 5.8% at five concentration levels (0.474 mu g/m(3) to 47.4 mu g/m(3).