Delay time dependence of inversion recovery curves obtained for HDO in D2O solutions

Inversion Recovery (IR) curves giving T1 have been obtained for protein solutions dissolved in H2O/D2O mixtures.However, initial IR curves of H2O/D2O mixtures have not been obtained yet.Such a study may be useful for interpretation of T1 data in protein solutions.In this work initial perts of IR curves for pure H2O + D2O mixtures (0.1 H2O + 0.9 D2O) were obtained for several sets of delay time to in IR pulse sequence [1800 ? ? ? 900].The measurements were carried out by a 400 Mhz NMR spectrometer andincreamental increase between two adjascent delays of each set was kept constant. The IR measurements for pure H2O/D2O were repeat at several days.The IR data of pure sample consists of four parts classifed as a cluster followed by a jump , followed by a triplet and followed by a curve. The cluster and the jump have been dissappeared gradually upon addition of albumin. The triplet was turned into four lines for the non-fresh sample measured day by day.The possible sources of this fragmentary data were analysed in terms of relaxation theory. The suggestions of this work can be summerised as follows:a)Jumping may be caused by a fast reaction in solventb)The triplet may be caused by the hyperfine splitting of H by D or by radiation damping. The additional line obtained for the delayed sample may be due to H/D Exchange in solvent.