Mass spectra of the methyl esters of cyclohexylnonanoic acid (upper panel) and cyclohexylundecanoic acid (lower panel) derived from the anaerobic enrichment culture with cyclohexane.

We tentatively identified, from their full scan negative ion-ESI mass spectra, MINCH and 12 urinary oxidative metabolites, including 4 cyclohexane ring oxidized metabolites (Table 1, Figures 2,3,4).