In recent years, several new methods have emerged for rapid NMR data collection. One class of methods is
projection NMR spectroscopy, which involves phase sensitive joint sampling of two or more chemical shifts in an indirect
dimension of a multidimensional NMR experiment. In the current implementations of this method, cosine/sine modulation
of all chemical shifts involved in the joint sampling are collected and stored as separate FIDs. A post-acquisition data
processing step (application of G-matrix) then separates the different inter-modulations of chemical shifts. Thus, joint
sampling of K+1 spins results in 2K combination of chemical shifts (also representing 2K projection angles). One limitation
of this approach is that even if only a few of the 2K components of the multiplet (or projection angles) is desired, an entire
data set containing information for all 2K shift combinations is collected. We propose here a simple method which releases
this restriction and allows one to selectively detect only the desired linear combination of chemical shifts/projection angles
out of 2K combinations in a phase sensitive manner. The method involves selecting the appropriate cosine/sine modulations
of chemical shifts and forming the desired linear combination by phase cycling of the radiofrequency pulses and
receiver. This will benefit applications where only certain linear combination of shifts are desired or/and are sufficient.
Further, G-matrix transformation required for forming the linear combination is performed within the pulse sequence.
This avoids the need for any post-acquisition data processing. Taken together, this mode of data acquisition will foster
new applications in projection NMR spectroscopy for rapid resonance assignment and structure determination.