Development and Successful Validation of Simple and Fast TLC Spot Tests for Determination of Kryptofix® 2.2.2 and Tetrabutylammonium in 18F-Labeled Radiopharmaceuticals

Kryptofix® 2.2.2 (Kry) or tetrabutylammonium (TBA) are commonly used as phase transfer catalysts in 18F-radiopharmaceutical productions for positron emission tomography (PET). Due to their toxicity, quality control has to be performed before administration of the tracer to assure that limit concentration of residual reagent is not reached. Here, we describe the successful development and pharmaceutical validation (for specificity, accuracy and detection limit) of a simplified color spot test on TLC plates. We were able to prove its applicability as a general, time and resources saving, easy to handle and reliable method in daily routine analyzing 18F-tracer formulations for Kry (in [18F]FDG or [18F]FECh) or TBA contaminations (in [18F]FLT) with special regard to complex matrix compositions.