Determination of oxygen by a nuclear magnetic resonance method

Abstract

A NMR technique is described for the determination of magnetic susceptibilities Δ χ v of oxygen solutions using a field-axis variation method. The technique is applied to the titration of oxygen in benzene or hexafluorobenzene solutions contained in sealed sample tubes under pressures of 1 to 6 atm. The validity of the method was checked by using both nuclei of each solvent, i.e., 1H (at 90 and 250 MHz) and 13C{ 1H} (22.63 and 62.86 MHz) for C 6H 6; 19F (84.67 and 250 MHz) and 13C{ 19F} for C 6F 6. The sensitivity limit is expecd to be Δ χ v = 0.03 × 10 −6 and [O 2] = 10 −3 mole · dm −3 (for 1H or 19F nuclei). This method might be used for a remote control of the oxygen content in organic solvents for oxygen pressures higher than 1 atm.