Nuclear magnetic resonance spectroscopy. Concentration dependence of the T_1 relaxation time for ^(13)C in dioxane-D_2O. Some experimental problems with T_1 measurements

Abstract

The ^(13)C T_1 relaxation times determined for dioxane-D_2O solutions by the progressive saturation method have been found to range from 5 sec for 1:1 (v/v) dioxane-D_2O to 12 sec for neat dioxane. The concentration dependence roughly parallels the inverse of the viscosity and is likely to be associated with changes in correlation times because of hydrogen bonding. A 2:1 (v/v) dioxane-D_2O mixture with a T_1 of 6.2 ± 0.6 sec at 30°C has been found to be a useful standard for checking instrument performance in the determination of T_1 values. A number of experimental problems associated with measuring T_1 are discussed.

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