Figure 3.

600 MHz ¹H NMR spectra of the urine from two different human volunteers in the region from 0.5 to 8.0 ppm, with expansion of the aromatic proton region (7.0–8.0 ppm) and a higher field region (2.0–2.8) shown above. (A) Pre-dose urine from volunteer 1; (B) 0–3 h post-dose NMR spectra from volunteer 1, The main differences between the pre-dose and post-dose spectra are the appearance of signals from paracetamol and its metabolites in both the aromatic and acetyl regions. (C,D) Corresponding pre- and post-dose spectra for volunteer 2. Key to peak numbers: 1, creatinine; 2, hippurate; 3, phenylacetylglutamine; 4, metabolite 4 (unknown at the time: see text); 5, citrate; 6, cluster of N-acetyl groups from paracetamol-related compounds; 7, paracetamol sulfate; 8, paracetamol glucuronide; 9, other paracetamol-related compounds. Reproduced from PNAS (Clayton et al., 2009).