The 3D intra-HNCA experiment is specifically designed to correlate ¹⁵N and NH chemical shifts with the intraresidue ¹³CA carbon shifts by means of the ¹J(NH) and ^1,2J(N,CA) coupling constants.

Implementation on AVANCE spectrometers equipped with a third channel. Improved versions using pulsed field gradients (PFGs) are also available and, therefore, in such cases gradient technology is required.

The experiment is applied on ¹⁵N,¹³C-labeled proteins. Because the amide (NH) protons are involved, the HNCA experiment must be recorded in H₂O.

Intraresidue HNCA connectivities could be identified from 3D intra-HNCA experiment ( 02JMR155-156 and 02JB201 )

A related experiment is the intra-COHNCA experiments

The i-HNCA experiment can be recorded in automation mode. More details on practical implementation of the 3D HNCA experiment on AVANCE spectrometers can be found in the corresponding Tutorial: 3D i-HNCA experiment

The HNCA experiment affords a 3D spectrum in which ¹H, ¹⁵N and ¹³CA chemical shifts are displayed in three independent dimensions.

See list of 3D triple-resonance NMR experiments for doubly-labeled proteins.