Determination of parts per million levels of trifluoroacetic acid in ceronapril bulk substance by headspace capillary gas chromatography

A headspace capillary gas chromatographic method was developed to determine trifluoroacetic acid (TFA) in a bulk substance (ceronapril). The bulk sample is reacted in a sealed headspace vial with dimethyl sulfate in concentrated sulfuric acid to convert TFA to methyl trifluoroacetate (MTFA). A portion of the headspace of the vial containing the MTFA is chromatographed on a PoraPLOT Q 0.32 mm I.D. capillary column in the split injection mode with flame ionization detection. The limit of detection is less than 10 ppm (w/w).