Accumulation of trifluoroacetate in seasonal wetlands in California.

Trifluoroacetate (TFA, CF3COO-) is a stable and mildly phytotoxic breakdown product of several fluorinated organic compounds including the hydro(chloro)fluorocarbons (HFC/HCFCs) that have largely replaced the stratospheric ozone-depleting chlorofluorocarbons (CFCs). TFA enters aquatic ecosystems primarily through precipitation and has the potential to accumulate in water bodies with little or no outflow to the point where toxic concentrations could be achieved. This study demonstrated that seasonal wetlands lacking outflow concentrated TFA as they evaporated during the dry season. In addition, the TFA within the pools was retained between years, which may result in long-term TFA accumulation. Since plants acquire TFA from their growing media, the plants exposed to high aqueous concentrations of TFA within the pools had elevated TFA concentrations with a median concentration of 279 ng/g dry weight in their tissues as compared to 33 ng/g for species growing outside the pools. The highest TFA concentrations in water, which occurred just prior to the pools drying up, were in the 2-10 micrograms/L range. These concentrations are approximately 190 or less than reported toxic concentrations for the most sensitive species tested, but our evidence suggests that these concentrations will increase with continued TFA deposition into the pools.

Extraction and analysis of trifluoroacetic Acid in environmental waters.

Trifluoroacetic acid (TFA), a mildly phytotoxic compound, is a stable atmospheric breakdown product of HFC-134a, HCFC-123, and HCFC-124. An extraction and analytical method has been developed for the routine analysis of low ppt levels of TFA in aqueous samples. TFA can be quantitatively recovered from most environmental waters by an extraction procedure using a commercial anion-exchange disk. In saline samples (conductivity >620 µS), where the presence of competing anions interfered with recovery, a liquid-liquid extraction cleanup was necessary. After extraction of TFA from water, the dried disk was placed in a headspace vial containing 10% sulfuric acid in methanol and the vial sealed and then vortexed for 30 s. The sulfuric acid-methanol solution extracts trifluoroacetate anion (TFA) from the anion-exchange matrix and, when heated, quantitatively converts it to the methyl ester, which is then analyzed by automated headspace gas chromatography using electron capture or mass spectrometry detection. Several environmental samples in addition to laboratory spike solutions were successfully extracted and analyzed with this technique. Recoveries averaged 108.2% for reagent water spiked at levels from 53 to 2110 ng/L with relative standard deviations ranging from 0.3 to 8.4%. The instrument's limit of detection for TFA standard was 3.3 ng. The limit of quantitation for the extraction and analytical technique was 36 ng/L. Three water samples can be prepared for automated analysis in 20 min using this technique.