# HMQC / HSQC 1-bond CH correlation

Comparison of phase-sensitive HSQC using echo-antiecho (JEOL experiment name: **hsqc_pfg_s_phase_pn.exp** ) and magnitude mode HMQC (JEOL experiment name: **hmqc_irr_pfg_s.exp** ) (see notes about HMQC processing)

Comparison of experiments run on 4 mg codeine sample using

2 scans

128 t_{1}increments (note that because hsqc is phase sensitive, it takes twice as long to acquire the same number of t_{1}increments)

512 complex points in direct dimension

signal-to-noise ratio (S/N) measured at N-Me for HMQC (with phase of sine squared window fcn of 45) was twice that of HSQC, but S/N of the smaller peaks is comparable for both spectra.

HMQC: (total acquisition time ~9 min)

HSQC – note that peaks are sharper, so overlapping peaks are less of a problem. (total acquisition time ~18 min)

**Processing:**

HMQC:

sine squared window function in both dimensions with 45 degree phase shift

2x zero-fill in the indirect dimension

magnitude calculation (no phasing is required)

final data size 512 x 512

HSQC:

this is an echo-antiecho experiment; see details

sine squared window function in both dimensions with 90 degree phase shift

2x zero-fill in the indirect dimension

final data size 512 x 512

See also: Explanation of the HMQC experiment, processing HMQC data, HMBC

Last updated: 01/22/2003