Clean HMBC pulse seqence: suppression of strong-coupling induced artifacts in HMBC spectra

Clean HMBC is an HMBC experiment which features improved suppression of one-bond correlations by eliminating artefacts arising due to strong coupling.

τ and τ_i's are set for ¹J_CH with exact delay timing depending on the degree of filtering desired. Δ is the polarization transfer delay for ⁿJ_CH and δ is a gradient delay. Echo/antiecho spectra are recorded and the non-destructive filter is co-added on the fly so processing is identical to the standard HMBC experiment. The order of the initial and terminal low pass J filter (LPJF) add up to give the total order of filtration. The sensitivity of long-range correlations are unaffected by clean HMBC filtering mechanism.

Recommended phase cycle is an even number of scans out of:
φ₁={x,-x,-x,x}, φ₂={x,x,4(-x),x,x}, φ₃={4(x),4(y),4(-x),4(-y)}, and φ_rec={x,-x}.

A minimum of 4 scans are required to obtain a 2nd order terminal LPJF.

Spectral excerpts from the bulk region of mannose recorded at 500 MHz:

1D traces of the example shown above.

Standard HMBC (upper), Clean HMBC (middle), and signals suppressed by the novel filter implementation (lower).

Reference:

Würtz P, Permi P, Nielsen NC, Sørensen OW.
Clean HMBC: Suppression of strong-coupling induced artifacts in HMBC spectra.
J. Magn. Reson. 2008, 194(1):89-98. [PUBMED]

Clean HMBC: Suppression of strong-coupling induced artifacts in HMBC spectra

Download the complete package: cleanHMBC.tgz

Installation instructions:
Please read the disclaimer before using the sequence. For usage/processing refer to the manual page.