Separation of cyclosporins by high-performance liquid chromatography and mass spectrometric study of cyclosporin metabolites

Jari Tuominen (Corresponding Author), Tapani Suortti, K. Ishikawa, J. Lundell, Y. Koga

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A semi‐preparative (high‐performance liquid chromatography) method for separation of cyclosporin metabolites in a fungal fermentation sample was developed. By using the optimized chromatographic separation, 20 cyclosporin metabolites in a process sample were isolated, and their molecular masses measured by double focusing sector mass spectrometry. The structures of some of the cyclosporin congeners were investigated by tandem sector mass spectrometry using fast atom bombardment ionization. The isobaric cyclosporins D ([Val2]CS) and G ([Nva2]CS) were differentiated by significantly different relative intensities of a fragment ion at m/z 30 [CH4N]+ from a precursor ion at m/z 72 [C4H10N]+. Otherwise the tandem mass spectrometry (MS/MS) spectra of the fragment ions of the two isomers are very similar.
Cyclosporin A and iso‐cyclosporin A were also analysed by high energy MS/MS. No significant fragment ions were found to provide distinctions between them.
Relatively good overviews of process samples containing very similar structures were achieved by combining LC separation, molecular ion recognition and MS/MS characterization.
Original languageEnglish
Pages (from-to)1085-1091
JournalRapid Communications in Mass Spectrometry
Issue number16
Publication statusPublished - 1998
MoE publication typeA1 Journal article-refereed


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