Ibuprofen metabolite profiling using a combination of SPE/column-trapping and HPLC–micro-coil NMR

Solid-phase extraction and column-trapping preconcentration are combined to enhance HPLC–nuclear magnetic resonance (HPLC–NMR) and applied to metabolite profiling in biological samples. Combining the two signal enhancement techniques improved the NMR signal substantially such that we were able to identify 2-hydroxyibuprofen, carboxyibuprofen, and unmetabolized ibuprofen molecules from a small urine sample after a therapeutic dose of ibuprofen. The hyphenated SPE/column-trapping method resulted in an excellent overall signal enhancement of up to 90-fold.