Measurement of longitudinal relaxation times in crowded H-1 NMR spectra using one- and two-dimensional maximum quantum (MAXY) NMR spectroscopy

Methods for measuring longitudinal relaxation times of protons in heavily o verlapped H-1 NMR spectra are introduced and exemplified using a solution o f cholesteryl acetate. The methods are based on 1-dimensional and 2-dimensi onal maximum quantum NMR spectroscopy (MAXY), which makes possible the sele ctive detection of CH, CH2 and CH3 H-1 NMR resonances. A modification of th e BIRD pulse sequence to achieve selective inversion of protons bonded to e ither C-12 or C-13 is given. The approach should rnd application in studies of molecular dynamics where isotopic enrichment is not possible and the le vel of available sample dictates the use of H-1 NMR spectroscopy.