Data analysis for the competive study identified one signal at 1.32 ppm as significantly different between non-dosed samples and dosed samples. This signal is only visible for dosed samples. Data analysis could not identify further signals belonging to the same metabolite.
Multivariate data analysis identified the signal at 1.32 ppm as significantly changed for dosed animals (red samples are low-dosed animals and black samples are high-dosed animals). The signals are only visible for dosed animals.
Looking at the raw spectra of dosed samples this signal could be identified as singlet. This signal is only present for dosed samples. As the signal increases with time (highest signals at the end of the study), it could be excluded that this signal belongs to a drug metabolite (drug related compound). No metabolite was known with a singlet at that position and no other signals of this metabolite could be identified when comparing spectra of dosed samples and spectra of control samples. Therefore the application of dedicated structure elucidation techniques was necessary. As the concentration of the metabolite was rather low, a sample cleanup and enrichement was necessary. The figure below demonstrates, how the metabolite could be enriched. The concentration of the metabolite in the enriched sample should allow 2D-NMR experiments within feasible measurement times.
The signal at 1.32 ppm identified by data analysis is a singlet visible for the raw spectra of dosed samples. A sample cleanup and enrichement procedure resulted in an enrichement of the metabolite of interest.