ORGANIC-SOLVENT SYSTEMS FOR P-31 NUCLEAR-MAGNETIC-RESONANCE ANALYSIS OF LECITHIN PHOSPHOLIPIDS - APPLICATIONS TO 2-DIMENSIONAL GRADIENT-ENHANCED H-1-DETECTED HETERONUCLEAR MULTIPLE-QUANTUM COHERENCE EXPERIMENTS

P-31 NMR of lipid extracts is a reproducible, rapid, and nondegradativ e method for qualitative and quantitative analyses of phospholipid mix tures. This analysis, however, is hampered by the instability of the s olvent system commonly used for NMR spectroscopy (CHCl3/CH3OH/H2O-EDTA ). In this work we have investigated the effects of several monophasic solvent mixtures to overcome this disadvantage. Among these mixtures we have selected a solution of triethylamine, dimethylformamide, and g uanidinium chloride (Et(3)N/DMF-GH(+)) as the most efficient system. I n this solvent the chemical shift dispersion of the Slp signals is abo ut four times the frequency range observed in the standard chloroform- methanol-water system. Moreover, the stability of this solvent, as a m onophasic system, allows easy reproducibility of the analysis. The use of two-dimensional H-1-P-31 gradient-enhanced heteronuclear multiple quantum coherence experiments can further exploit the higher resolutio n of the signals obtained with this solvent system for the structure e lucidation of known and unidentified phospholipids. (C) 1997 Academic Press.