High-performance liquid chromatographic assay of the magnetic resonance imaging contrast agent gadobenate in plasma, urine and bile.

Gadobenate dimeglumine (Gd-BOPTA-Dimeg) is currently under evaluation as an intravascular paramagnetic contrast agent for magnetic resonance imaging. The anion Gd-BOPTA2- is the moiety of Gd-BOPTA-Dimeg responsible for contrast enhancement. An HPLC method for assaying gadobenate (Gd-BOPTA2-) in plasma, urine and bile samples is described. The analysis is based on the reversed-phase chromatographic separation of the ion pair Gd-BOPTA(2-)-tetrabutylammonium from the endogenous components of biological fluids and its detection by UV absorption at 210 nm. The mean accuracy and precision of the method were in the range -3.4 to +5.0% and 0.2-3.5%, respectively. The method detection limits for Gd-BOPTA2- in plasma (0.8 ml), urine (0.2 ml) and bile (1.0 ml) were 1.1, 7.6 and 1.7 microM (corresponding to 0.73, 5.1 and 1.1 micrograms/ml), respectively.