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

O-phospho-l-threonine is a convenient sample to setup a 1H-31P-13C double cross-polarization (DCP) Hartmann-Hahn match. The 1H-31P-13C 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 31P 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. 31P-13C 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 1H-31P-13C experiments is demonstrated on model samples; disodium ATP hydrate and O-phospho-l-tyrosine.