A practical guide for the setup of a 1H-31P-13C double cross-polarization (DCP) experiment.

Abstract O-phospho- l -threonine is a convenient sample to setup a 1 H– 31 P– 13 C double cross-polarization (DCP) Hartmann–Hahn match. The 1 H– 31 P– 13 C technique is extremely sensitive to the rate of the sample spinning. Both zero-quantum (ZQ) and double-quantum (DQ) cross-polarization operate at an average spinning rate (6–7 kHz). At higher spinning rates (10 kHz), the DQCP mechanism dominates and leads to a reduction of signal intensity, in particular for lower 31 P RF field strength. The application of two shape pulses during the second cross-polarization greatly improves the signal to noise ratio allowing the recording of better quality spectra. 31 P– 13 C spectrally induced filtering in combination with cross-polarization (SPECIFIC-CP) experiments can be carried out under ZQCP and DQCP conditions if careful attention is paid to the choice of RF field amplitudes and carriers Ω . Application of 1D and 2D 1 H– 31 P– 13 C experiments is demonstrated on model samples; disodium ATP hydrate and O-phospho- l -tyrosine.