Determination of trifluoroacetic acid in water samples by gas chromatograph-mass spectrometry

A method was presented for the analysis of trifluoroacetic acid(TFA) in water samples.After spiked with internal standard pentafluoropropionic acid(PFPA),water samples were reduced to about 50 mL in volume using a rotary evaporator at 50 ℃,and then the derivatization reaction occurred in an aqueous mixture using 2,4-difluoroline(2,4-DFAn) to produce the acid anilide,with ethyl acetate as solvent and N,N′-dicyclohexylcarbodiimide as the catalyst.A series of extraction,purification and concentration were conducted before TFA anilide product was analyzed by gas chromatography with mass selective detector in the selected ion monitoring mode.Good linear correlation coefficient(R20.997) was observed between the concentrations and responses for TFA and PFPA mixed standard solutions in the range of 0.61～24.4 μg/L in ethyl acetate.The method detection limit was 1.8 ng/L for 500 mL water sample.Recoveries in fortified samples were in the range of 79.3%～94.8%.The method was highly sensitive for the determination of trifluoroacetic acid in environmental water samples.