Determination of Perfluoro-octanoic Acid and Its Salts in Fluoro-paint by Gas-chromatography-Mass Spectrometry

Perfluoro-octanoic acid (PFOA) and its salts were extracted ultrasonically with methanol from the paint sample,and the extract was concentrated by passing through a silica gel column with a layer of anhydrous Na2SO4 (ca. 1 cm) over the silica gel. An aliquot of the sample solution was taken and derivatized with acetylchloride to give methyl ester of PFOA. Methyl ester of perfluorodecanoic acid was used as internal standard in the GC/MS determination. Analytical conditions of GC/MS were given in detail. Linearity range of the method was found from 1.0-1×105μg·L-1 (r=0.999 7),with detection limit of 0.1 μg·L-1. Tests for precision and recovery of the method were performed at concentration levels of 100 μg·L-1 and 1 000 μg·L-1 of PFOA,values of RSD′s (n=6) found were 4.24% and 3.58% respectively,and recovery obtained were in the range from 86% to 111%.