USE OF LANTHANIDE SHIFT-REAGENTS WITH P-31 FT-NMR SPECTROSCOPY TO ANALYZE CONCENTRATED LAKE-WATER SAMPLES

Several lanthanide shift reagents (LSR) were synthesized from praseody mium, europium, dysprosium, and terbium using ethylenediaminetetraacet ic acid, trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, and diethylenetriaminepentaacetic acid for the purpose of separating overl apping P-31 FT-NMR spectral signals of dissolved organic phosphorus co mpounds present in concentrated lake-water samples. The extent of chan ge in signal position and line width of several known phosphorus compo unds dissolved in pure water was examined as a function of solution pH and the molar ratio of LSR to phosphorus. Praseodymium ethylenediamin etetraacetate (PrEDTA) was determined to be the most effective LSR. Co ncentrated lake-water samples mixed with PrEDTA were examined with P-3 1 FT-NMR. The use. of PrEDTA provided separation of overlapping signal s, indicated that phosphorus compounds were becoming isolated from the solution environment during sample concentration, enhanced the sensit ivity of certain signals by possibly acting as a T1 relaxation agent, and did not precipitate in the presence of a high concentration of hum ic and fulvic acids.