Post-column derivatization high-performance liquid chromatography-ultraviolet-ultraviolet (HPLC-UV) method for the...

A post-column derivatization high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed to determine Kryptofix 2.2.2 (K2.2.2) in PET tracers. This method utilizes the specific complexation between K2.2.2 and Pb²⁺, forming a stable 1:1 host-guest complex. The complexation produces a bathochromic shift in UV absorption maximum (from 210 nm to 254 nm), enabling sensitive detection. This approach addresses the limitations of poor performance and narrow applicability associated with direct single-method detection of K2.2.2. The chromatographic conditions were optimized (column flow rate: 0.7 mL·min^-1; derivatization reagent flow rate: 0.7 mL·min^-1; Pb²⁺ concentration: 50 μg·mL^-1) and the method was validated. The results exhibited excellent linearity (1-100 μg·mL^-1, r² > 0.999), high reproducibility (relative standard deviation (RSD) < 5%), and a low detection limit (0.5 μg·mL^-1). The method successfully quantified K2.2.2 in [¹⁸F]FDG, [¹⁸F]AV45 and [¹⁸F]DPA714, achieving spiked recoveries of 89%-105%. Additionally, the method remained unaffected by interference from common sample components such as sodium chloride and sodium ascorbate. This method provides a novel and efficient quality control tool for the simultaneous analysis of radiochemical purity and K2.2.2 content in diverse PET tracers.