TFA is an abbreviation used for trifluoroacetic acid.

This acid is commonly used in HPLC methods because it has some ion-pairing characteristics and is therefore used where peak tailing due to causes such as silanophilic effects is an issue.

It is generally considered to be not compatible with LCMS except when used in very low concentrations (~0.005%). It is very well suited for UV methods and is generally used as ~0.1% (v/v). It is soluble in both neat DI water and neat acetonitrile so it can be used in A and B solvents as DI water + 0.1% TFA and Acetonitrile + 0.1% TFA.