A Comparison of the hyphenated experiments GHMQC-TOCSY and GHSQC-TOCSY

Heteronuclear shift correlations generally may be established using either the multiple quantum-based GHMQC experiment or, alternately, the single quantum-based GHSQC experiment. A scant few reports contained in the literature have compared results obtained with both types of sequences. The F₁ resolution of the GHMQC and GHSQC experiments are compared using the polynuclear heteroaromatic naphtho-2′,1′:5,6]naphtho2′,1′:4,5]thieno2,3-c]quinoline. Even when augmented by linear prediction in F₁, the single quantum-based GHSQC sequence gives better F₁ resolution than its multiple quantum counterpart. To date, no studies have compared the hyphenated analogs of these experiments, GHMQC- and GHSQC- TOCSY. Similar conclusions to GHMQC/GHSQC are drawn for the comparison of GHMQC- and GHSQC- TOCSY experiments with inverted direct responses with, and without, linear prediction. The latter is recommended whenever there is congestion in both the F₂ and F₁ frequency domains.