Metabolism of an ionic contrast medium and the related agents

Liquid chromatography–atmospheric pressure chemical ionization mass spectrometry was applied to analyze the iodinated compounds and their glycine conjugates. The negative-ion mass spectra of the iodinated compounds gave [M−H]−, [M−COOH]− and [I]− ions. The positive- and negative-ion mass spectra of the glycine conjugates showed abundant [M+H]+ and [M−H]− ions. Fragmentations of the glycine conjugates obtained in the positive-ion mode were different from those in the negative-ion mode, the former providing more useful structural information for the presence of glycine. Mouse kidney mitochondria were more active in glycine conjugation than liver mitochondria. Mono-substituted benzoic acids were conjugated with glycine in liver and kidney, whereas the acids having three functional groups or more did not undergo glycine conjugation in liver and kidney.