Tetrabutylammonium HPLC analysis: shortcomings in the Ph. Eur. method

Abstract Tetrabutylammonium is a phase‐transfer agent commonly used in PET radiochemistry. Its toxicity makes its quantification mandatory. However, the official HPLC method for tetrabutylammonium analysis reported in the European Pharmacopoeia (Ph. Eur.) apparently fails to achieve the described separation in most new generation reverse‐phase columns. The study highlights the differences in separation achievable by varying some of the chromatographic conditions, such as temperature, eluent composition and ion‐pairing agent concentration. In the end, variations to the method within the limits allowed by the Ph. Eur. were not sufficient to overcome the problem, thus forcing to a more radical change of the organic component of the mobile phase.