Simplified Method for Trace Analysis of Trifluoroacetic Acid in Plant, Soil, and Water Samples Using Headspace Gas Chromatography

A simple and sensitive analytical procedure was developed to determine the concentration of trifluoroacetic acid (TFA) in plant, soil, and water samples. The analysis involves extraction of TFA by sulfuric acid and methanol followed by derivatization to the methyl ester of TFA (MTFA). This is accomplished within a single vial without complex extraction procedures. The highly volatile MTFA is then analyzed using headspace gas chromatography. The spike recovery trials from all media ranged from a low of 86.7% to a high of 121.4%. The relative standard deviations (RSDs) were typically below 10%, although some tests had higher RSDs due to low concentrations near the detectable limit. The minimum detectable limit (MDL) for the method was 34 ng/g for dry plant material, 0.20 ng/g for soil, and 6.5 ng/L for water. This is the first practical method for low-level analysis of TFA in plants and soil, and it is a significant improvement over previous methods for TFA in water.