Standards Development

Scope

This document specifies a method for the determination of trifluoroacetic acid (TFA) in drinking water, ground water, and surface water using liquid chromatography and mass spectrometric detection. A working range from ≥ 0,1 µg/l and 3 µg/l can be assumed, depending on the matrix. The determination is performed by direct injection (e.g., 10 µl).

The method can also be applied to other waters (e.g. mineral water, rainwater, wastewater); however, its applicability shall be verified in each individual case. Depending on the salt concentrations and the suspended loads, limitations regarding the working range shall be expected.

The lower application limit of this method shall be considered variable as a function of the sensitivity of the equipment employed, the blank value conditions within the measurement system, and the characteristics of the sample matrix. 

The method could also be applied to other analytes; however, this needs to be verified in each individual case.

Purpose

Being a strong acid, trifluoroacetic acid (TFA) is present in the aquatic environment almost exclusively in the form of its anion trifluoroacetate. TFA is an important starting material for the synthesis of numerous trifluoromethylated substances, such as pesticides and active pharmaceutical ingredients. TFA is also used for peptide synthesis and as a solvent and catalyst in polymerisation and condensation reactions.

At present, almost ten million synthetic substances with at least one CF3 group in their molecular structure are known [1] which are released into the environment in the course of their intended use or due to losses during product ion and transport. In addition to its direct entry into the aquatic environment from primary sources, TFA can be formed as a potential degradation product in the environment during the degradation of all substances that contain at least one carbon­bonded 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 entry pathways, TFA is ubiquitous in the aquatic system.

[1] CAS, 2021. SciFinder, a CAS Solution, American Chemical Society.

[2] Scheurer, M., Nödler, K., Freeling, F., Janda, J., Happel, O., Riegel, M., Müller, U., Storck, F.R., Fleig, M., Lange, F.T., Brunsch, A., Brauch, H.­J., 2017. Small, mobile, persistent: Trifluoroacetate in the water cycle — Overlooked sources, pathways, and consequences for drinking water supply. Water research 126, 460–471.

[3] Solomon, K.R., Velders, G.J.M., Wilson, S.R., Madronich, S., Longstreth, J., Aucamp, P.J., Bornman, J.F., 2016. Sources, fates, toxicity, and risks of trifluoroacetic acid and its salts: Relevance to substances regulated under the Montreal and Kyoto Protocols. Journal of toxicology and environmental health. Part B, Critical reviews 19 (7), 289–304.

[4] Tisler, S., Zindler, F., Freeling, F., Nödler, K., Toelgyesi, L., Braunbeck, T., Zwiener, C., 2019. Transformation Products of Fluoxetine Formed by Photodegradation in Water and Biodegradation in Zebrafish Embryos (Danio rerio). Environ. Sci. Technol. 53 (13), 7400–7409.

The proposal WI is based on DIN 38407­53 „Deutsche Einheitsverfahren zur Wasser­, Abwasser­ und Schlammuntersuchung — Gemeinsam erfassbare Stoffgruppen (Gruppe F) — Teil 53: Bestimmung von Trifluoressigsäure (TFA) in Wasser — Verfahren mittels

Flüssigkeitschromatographie und massenspektrometrischer Detektion (LC MS/MS) nach Direktinjektion (F 53)” with the aim to develop an European standard.