A spot test for determination of residual TBA levels in¹⁸F-radiotracers for human use using Dragendorff reagent

Abstract

When utilizing [18F]tetrabutylammonium fluoride ([18]TBAF) in the synthesis of 18F-labeled radiotracers for clinical positron emission tomgraphy (PET) imaging, it is necessary to confirm that residual TBA levels in formulated doses...

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“…Satisfactory and rapid results were obtained upon immersing the developed plate in Dragendorff's reagent for 30 seconds, with intense orange spots achieved for ALF and SOL. 35,36 This may be attributed to the abundance of nitrogenous groups in the chemical structures of ALF and SOL (Fig. S1A†).…”

“…The developed plates were divided into two equal parts along the direction of mobile phase development so that every developed track was adequately tted in the camera's eld of view. Each part was immersed in Dragendorff's reagent 33,35,36 for 30 seconds, rinsed with a small amount of distilled water and le until complete dryness. Aer that, the plates were xed on the bottom lid of the illumination chamber using the paper clip and illuminated under the daylight LED strip.…”

SNAr Radiofluorination with In Situ Generated [18F]Tetramethylammonium Fluoride

“…Lastly, one of the automated production batches was reformulated into 10% ethanol in saline using a C18 cartridge. We analyzed the formulated product for residual tetramethylammonium salts using recently developed TLC methods . This analysis shows levels below the accepted regulatory limits (not more than 2.6 mg/10 mL patient dose), promising results for translation of this methodology to the production of PET radiotracers for clinical use.…”

“…Radio-TLC analyses were performed using a Bioscan AR 2000 Radio-TLC scanner with EMD Millipore TLC silica gel 60 plates (3.0 cm wide × 6.5 cm long). Residual TMA levels were determined using TLC spot tests as previously described . Chromatography was performed using the following conditions.…”

Multi-patient dose synthesis of [18F]Flumazenil via a copper-mediated 18F-fluorination

“…However, using this oxalate-based eluent resulted in substantial losses through the QMA (66 ± 19% recovery, n = 3). Switching to a solution of TBA-HCO 3 as QMA eluent dramatically improved both the reliability Tanzey et al 2020), giving an official guideline to verify the residual content of TBA-HCO 3 in the final product vial, which is not the case for oxalate-based eluents. Gratifyingly, commercially available carbonated QMA could be used without the need for manual conditioning of the cartridge.…”