DOI: 10.1186/s13550-018-0449-6Pages: 1-10

Development and evaluation of a rapid analysis for HEPES determination in 68Ga-radiotracers

1. Medical University of Vienna, Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy

2. University of Vienna, Department of Inorganic Chemistry

3. Ludwig Boltzmann Institute Applied Diagnostics

4. CBmed – Center for Biomarker Research in Medicine

Correspondence to:
Wolfgang Wadsak
Tel: +43 (1) 40400-55330




HEPES is a favorable buffer for 68Ga-complexations in radiochemical laboratories. The drawback of this buffer is its prescribed limit of 200 μg per recommended application volume in the final formulation. Currently, a TLC test according to the European Pharmacopoeia (Ph. Eur.) has to be performed for quantification, but this analysis suffers from low reliability and reproducibility and is based on a subjective, semi-quantitative visual evaluation. In this study, the TLC method according to the Ph. Eur. and two literature-known HPLC assays for HEPES quantification were evaluated. Additionally, the development of an improved TLC method was performed.


The assay according to Antunes et al. provided a reasonable quantification of HEPES using HPLC. Additionally, a reliable and conclusive TLC method was developed, which facilitates quantitative analysis by means of a pixel-based evaluation. A comparison of those two methods with the Ph. Eur. TLC assay pinpoints the superiority of the HPLC as well as the new TLC assay. Furthermore, evaluation of HEPES contents using both TLC assays by 28 subjects supported the conclusion that the newly developed TLC method is clearly favorable.


The TLC method according to the Ph. Eur. provides unsatisfactory results in terms of conclusiveness and reproducibility. In contrast, a reported HPLC assay showed valid results, with the drawback of high technical effort. An optimized alternative is provided by the improved TLC method described in this work that results in reliable outcomes and additionally offers quantitative analysis.

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  • Accepted: Oct 10, 2018
  • Online: Oct 23, 2018

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