Triple Resonance Isotope-Edited (TRIED): A powerful new NMR technique for studying metabolism

A powerful new technique for studying metabolism, Triple-Resonance Isotope-Edited (TRIED) NMR, is described and demonstrated experimentally. The experiment uses through-bond (scalar) coupling between spins to select NMR signals from molecules having ¹H-¹³C-¹⁵N labeled triples. Natural-abundance background signal from molecules not containing such labeled triples (e.g., signal from ¹H-¹²C and ¹H-¹³C fragments) is effectively suppressed, with a suppression ratio of approximately 10⁴:1. This effective filtering of signal from labeled molecules allows these species and their metabolites to be detected and characterized without requiring extensive, time-consuming sample purification. Results are presented for ¹³C,¹⁵N-aminomethylphosphonate (AMPA) in soybean and pigweed plant matrices. The potential use of TRIED for studying the pharmacokinetics of drugs and extension of the experiment to include the use of magnetic-field gradients for selecting signal from labeled fragments are also described.