Comparison of the electrospray ionization (ESI) responses of penicillins with ESI responses of their methanolysis products

Abstract

The electrospray ionization (ESI) responses, defined as the area of chromatographic peak of ion [M+H]+ obtained upon HPLC/ESI-MS analysis, of three β-lactam antibiotics, namely penicillin G, ampicillin and carbenicillin have been compared with the ESI responses of their methanolysis products. It has been found that methanolyzed penicillin G has much higher ESI response than the penicillin G. Methanolyzed ampicillin also has higher ESI response than ampicillin; however, the effect is less pronounced than for penicillin. Methanolyzed carbenicillin does not have pronouncedly higher ESI response than carbenicillin.