Detection of natural abundance nitrogen-15 through phosphorus-31 using pulsed field gradients

NMR characterization of natural abundance N-15 in phosphorus-nitrogen compo unds can be performed through P-31 using inverse detection methods. When th e P-31-N-15 scalar coupling is small, its observation is greatly disturbed by the residual signal coming from the 99.6% abundant N-14 isotopomer that usually is not completely suppressed by the phase cycle of the sequence. Th e combined use of pulsed field gradients to suppress this residual signal a nd the enhanced sensitivity P-31,N-15{H-1}-esHSQC experiment affords artifa ct-free spectra with good signal-to-noise ratio, which allows the accurate measurement of N-15 NMR parameters such as chemical shifts and coupling con stants with the benefits of phosphorus detection, (C) 2001 Academic Press.