Comparison of HPLC, TLC and minicolumn for measuring the radiochemical purity of 99Tcm-Q12.

TechneScan Q12 (99Tcm-Q12) is a new agent for clinical myocardial perfusion imaging. A product with high radiochemical purity is essential for high-quality imaging. We compared three methods of radiochemical purity analysis for 99Tcm-Q12: thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and minicolumn. Thin-layer chromatography resulted in lower purity (87 +/- 8%) than the minicolumn method (aluminium oxide minicolumn, ethanol) (95 +/- 4%). The HPLC method resulted in the lowest purity (79 +/- 11%). The main impurity was a polar compound, but three further impurities were found using HPLC. Using HPLC, we found the percentage of the parent compound (99Tcm-Q12) in plasma at 40-90 min post-injection to be 19.3 +/- 6.2%. We suggest that gradient HPLC is the most effective method for the analysis of the radiochemical purity of 99Tcm-Q12, and that it can be used to determine the concentration of 99Tcm-Q12 in plasma.