DIN 38407-53:2025-10

As a result of its strong tendency to deprotonate in an aqueous environment, trifluoroacetic acid is found almost exclusively in the form of its anion, trifluoroacetate. It is an important source material for the synthesis of numerous substances, enabling the incorporation of trifluoromethyl groups (-CF3) into complex molecules, such as pesticides and active pharmaceutical ingredients. In addition, TFA is used for peptide synthesis, as well as a solvent and catalyst in polymerization and condensation reactions. Currently, nearly ten million synthetic substances with at least one CF3 group in their molecular structure are known, and these enter the environment either through their intended use or due to losses during production and transport. Apart from direct release into the aquatic environment, TFA can potentially form in the environment as a degradation product during the breakdown of all substances that contain at least one carbon-bonded CF3 group in their molecular structure [2], [3], and [4]. TFA is classified as highly persistent in the environment, as the trifluoromethyl group is extremely resistant to (bio)chemical degradation processes. As a result of its high mobility and stability, as well as diverse pathways of entry, TFA is now practically ubiquitous in the aquatic system in Germany and has already been detected in various compartments of the water cycle. This document specifies a method for the determination of trifluoroacetic acid (TFA) (molecular formula: C2HF3O2; CAS No.: 76-05-1) in drinking water, groundwater, and surface water using liquid chromatography and mass spectrometric detection. Depending on the matrix, a working range between ≥ 0,1 µg/L and 3 µg/L can be assumed. The determination is performed by direct injection (for example, 10 µL). The applicability of the method to other water types (for example, mineral water, rainwater, wastewater) is not excluded; its suitability shall be verified on an individual case basis. Restrictions with regard to the working range have to be expected as a function of the salinity and the suspended sediment concentration. The lower limit of application of the method may vary depending on the sensitivity of the equipment used, the system-related blank value situation, and the sample matrix. This document has been prepared by Working Group NA 119-09-02-16 AK "LC-MS/MS methods" of Working Committee NA 119-09-02 AA "Chemisch-physikalische Verfahren einschließlich Qualitätssicherung" ("Chemical-physical methods including quality assurance") at Section NA 119-09 FB "Water quality (CEN/TC 230, ISO/TC 147)" at DIN Standards Committee Water Practice (NAW).