On-flow identification of metabolites of paracetamol from human urine using directly coupled CZE–NMR and CEC–NMR spectroscopy

Direct NMR spectroscopic detection on-flow to capillary electrophoresis (CE) or capillary electrochromatography (CEC) was applied to the separation of metabolites of paracetamol from an extract of human urine. The detection and characterisation of the major metabolites, the glucuronide and sulfate conjugates of the drug as well as identification of the endogenous material hippurate was achieved. This demonstrates that NMR detection and identification of drug metabolites is possible with nanolitre volumes of analyte.