Ether and ester glucuronic acid conjugates of lacidipine metabolites: Mass spectrometric differentiation using thermospray and particle beam techniques

Glucuronic acid conjugates of Lacidipine metabolites were analysed by high‐performance liquid chromatog‐raphy/mass spectrometry with different ionization techniques, viz. thermospray and chemical ionization with a particle beam interface. Analyses were performed on bile samples collected from dogs after oral administration of 14C‐labelled Lacidipine. Phase II metabolites, originating from the conjugation with glucuronic acid of phase I metabolites containing free hydroxy or carboxylic functions, were isolated. Two types of glucuronides, with an ether or an ester bond, were characterized. They showed different mass Spectrometric behaviour owing to a specific interaction with the acetate in the mobile phase.