The effect of various acquisition and processing parameters on the sensitivity of HMBC spectra for typical organic molecules has been systematically investigated. For molecules in the 200-600 molecular weight range, an acquisition time of 0.2 to 0.4 s, a recycle time of no more than 1.0 s, optimization for (n)J(CH) = 8 Hz and 512 time increments (with two- to fourfold linear prediction) are recommended. Some form of sine bell weighting along f2 and either Gaussian or sine bell weighting along f1 is suggested. The use of a 0.1-s acquisition time and/or Gaussian or exponential weighting along f2 can result in dramatic sensitivity loss, particularly for correlation peaks involving protons with complex splitting patterns, and should be avoided.
Copyright 2009 John Wiley & Sons, Ltd.