A critical study on borosilicate glassware and silica-based QMA's in nucleophilic substitution with [18F]fluoride: influence of aluminum, boron and silicon on the reactivity of [18F]fluoride

Leachables of borosilicate glassware and silica-based anion exchange columns (QMAs) may influence nucleophilic substitution with [18F]fluoride ([18F]F−). Aluminum, boron and silicon, all constituents of borosilicate glass, were found as water soluble leachables in a typical PET synthesis setup. Relevant ranges of the leachable quantities were studied based on an experimental design, in which species of the three elements were added to the labeling of the precursor for anti-1-amino-3-[18F]fluorocyclobutyl-1-carboxylic acid ([18F]FACBC). Levels of 0.4-2 ppm aluminum as AlCl3 had a strong negative influence on labeling yield while 4-20 ppm of boron as KBO2 and 50-250 ppm of silicon as Na2SiO3 did not have a significant impact. Interesting interaction effects between the elements were observed, where particularly KBO2 reduced the negative effect of AlCl3 on labeling yield. It can be concluded that leachables of borosilicate glassware easily can influence nucleophilic substitution with n.c.a. [18F]F− and give variable yields.