Human Urinary Metabolite Quantification in Nuclear Magnetic Resonance-based Metabonomics Using Electronic Reference

A complete assessment for urinary quantitative analysis was reported using an electronic signal as an internal reference, which was generated through decoupling channel on a Varian nuclear magnetic resonance spectrometer with its amplitude, frequency, and transverse relaxation time digitally programmable according to a decoupling shape file. The electronic signal with excellent stability (standard deviation 0.36%) avoided possible problems such as insolubility, interaction, and spectral overlap for a traditional internal reference. Concentration determination using the electronic signal proved to be reliable by a series of quantitative experiments. The accuracy of quantification was about 1% and 5% when the analyte concentration was more than 20 mM and less than 2 mM, respectively. The concentration of human urinary metabolites were measured in a simultaneous fashion using this electronic internal reference and obtained consistent results with the values measured by the biochemical analytical instrument used in hospital.