Manchester NMR Methodology Group

Diffusion-ordered spectroscopy (DOSY) is a powerful method for the NMR analysis of mixtures such as crude synthetic products, biofluids or biological extracts. Mixtures can be analysed without the need for any physical separation, and the method requires only standard NMR pulsed field gradient hardware. Existing pulse sequences for DOSY require extensive and time-consuming phase cycling for clean results. A new sequence is reported here which allows clean spectra with good lineshapes to be obtained using as little as one transient per gradient value. Asymmetric bipolar field gradient pulse pairs are used in conjunction with extra balancing gradient pulses, selecting a unique coherence transfer pathway but minimizing eddy current effects and field-frequency lock disturbance. Using the new sequence, high-resolution proton DOSY spectra can be obtained in less than 1 min. Copyright (C) 2002 John Wiley Sons, Ltd.