HPLC-MS Method for the Separation of Fluorophenylacetic Acid Isomers

2-Fluorophenylacetic acid is a widely used chiral derivatizing agent in 19F NMR spectroscopy. 3-Fluorophenylacetic acid serves as a key precursor in the synthesis of various pentaamine and bis-heterocyclic compounds, while 4-Fluorophenylacetic acid is commonly used as an intermediate in the production of fluorinated anesthetics. Although these three compounds share the same chemical formula, the position of the fluorine atom differs, leading to slight variations in their retention and chromatographic behavior.
All three isomers can be detected at low UV wavelengths. Using a Zodiac HST SB reverse-phase column and a mobile phase composed of acetonitrile (MeCN) and water, buffered with either formic acid or acetic acid, the fluorophenylacetic acid isomers can be effectively retained, separated, and UV-detected at 264 nm with high precision and resolution. This method is fully compatible with mass spectrometry.