STATISTICAL-ANALYSIS OF NMR PROTON SPIN-LATTICE RELAXATION RATES MEASURED AT VARIOUS PULSE REPETITION TIMES

Abstract

In this work, taking into consideration waiting time (WT) in successive automatic measurement, the effect of pulse repetition time (T-R) on spin-lattice relaxation time (T-1) was studied by a FT-NMR spectrometer. Inversion-recovery pulse sequence 180 degrees-tau-90 degrees(FID)+T-R+WT was successively applied for a set of 10 different tau. T-1 was calculated from non-linear estimation of inversion recovery formula, using partially relaxed recovery signals corresponding to different tau. Holding WT constant, T-R was set at 6 diferent values, ranging from nearly 6T(1) to 0.7T(1). T-1 measurements were repeated 20 times for each T-R. For comparison T-1 measurements were also repeated by the null method. Data showed that the intensity of recovery signals after total waiting (T-R+WT) has the same value for all T(R)s and comparison of T-1 groups corresponding to these T(R)s indicates no significant difference among T-1 values measured (p>0.2). Keeping T-R+WT>5T(1), to reduce T-R more causes an imperfect signal. The results suggest that WT makes possible the use of a T-R shorter than 5T(1) and saves experimental time.