Using the IPAP approach, two separate HSQC experiments are recorded to generate in-phase and anti-phase cross-peaks. The sum and difference of such spectra affords spin-state separatedcross-peaks that allow the measurement of residual 1H-15N dipolar coupling constants with high accuracy

Easy implementation on any AVANCE spectrometer equipped with pulsed field gradients (PFGs) and inverse probehead.

The original HSQC-IPAP experiment was described in 98JMR373-131 and other related schemes have been also proposed ( 99JB175-13 and 99JMR32-140 ).

HSQC-IPAP experiment to suppress NH2 signals ( 01JB141-21)

The ge-2D HSQC experiment is usually recorded in routine and automation modes. Minor changes are required if a predefined parameter set is available.

More details on practical implementation of ge-2D HSQC experiments on AVANCE spectrometers can be found in the corresponding tutorials:

Tutorials: 2D inverse experiments

Tutorials: 2D gradient-based inverse experiments

The HSQC-IPAP spectrum correlates chemical shifts of heteronucleus X (F₂ dimension) and protons (F₁ dimension) via the direct heteronuclear coupling ¹J(XH). The effective suppression of unwanted ¹H-¹²C or ¹H-¹⁴N magnetization by means of PFGs allows to obtain ultra-clean 2D spectra from which clear analysis can be done.

Related experiments:

2D Inverse experiments

2D Inverse gradient-enhanced experiments