NMR IMAGING OF THE CHROMATOGRAPHIC PROCESS - MIGRATION AND SEPARATIONOF BANDS OF GADOLINIUM CHELATES

The presence of gadolinium nuclei accelerates the relaxation of proton s in their neighborhood. Using the imaging techniques of nuclear magne tic resonance developed for medical diagnosis, it is possible to obser ve the chromatographic bands of Gadolinium compounds which appear in s hades of grey turning lighter with increasing gadolinium concentration . The existence of unexpectedly wide distributions of the local mobile phase velocity and the local height equivalent to a theoretical plate in an efficient chromatographic column is illustrated. The formation and resorption of fissured and/or compact zones in the column where th e external porosity appears lower or higher than average is documented for the first time.