Seasonal variation of trifluoroacetic acid (TFA) in Antarctic ice cores analysed by direct injection non-suppressed ion chromatography-mass spectrometry (nsIC-MS)

This study presents the first record of trifluoroacetic acid (TFA) in Antarctic ice cores, offering valuable data on TFA and its precursors' long-range atmospheric transport and deposition in remote polar regions. TFA is an ultra-short chain perfluoroalkyl acid (PFAA) that has gained attention due to its environmental persistence, stability, and mobility. It is primarily formed as an end product of atmospheric degradation of halogenated refrigerants and blowing agents, particularly hydrofluorocarbons (HFCs) and unsaturated HFCs (u-HFCs). In this study, a new non-suppressed ion chromatography-tandem mass spectrometry (nsIC-MS/MS) method was developed for TFA determination in samples from a 12.9 m Antarctic ice core. Using direct injection of 20 μL of ice core sample, TFA was retained on a HALO Penta-HILIC column (150 mm × 1.5 mm, 2.7 μm). Analysis was completed within 5 min at 25 °C using an isocratic mobile phase (60:40 acetonitrile:water, 1 mM ammonium formate) at 90 μL/min. Detection was performed in negative ESI-SRM mode (m/z 113 → 69), achieving a limit of detection of 0.3 ng/L. Repeatability (intra- and inter-day) was better than 7 %. A total of 260 samples were analysed from a high-resolution ice core spanning 2011–2021 CE. On average, TFA concentrations increased by 5.8 % per year over the studied period. Comparison with seasonal proxies from the same core, i.e., methanesulfonic acid (MSA), revealed TFA peaks in September–November suggesting that polar vortex weakening releases both pre-formed TFA and additional TFA from the breakdown of more stable precursors.