A method of detecting a solute in a solvent using nuclear magnetic resonance, wherein the solute performs chemical exchange of a proton with the solvent, said method comprising the steps of: encoding an excitation in a nuclear spin of the solute comprising at least one preparation sequence, wherein said preparation sequence comprises the steps of: - applying a first radiofrequency pulse to the nuclear spin at a resonance frequency of the solute; and - applying a first magnetic field gradient pulse suitable for changing a phase of the nuclear spin; and measuring the excitation in the nuclear spin, said measuring including the steps of: - applying a refocusing radiofrequency pulse at a resonance frequency of the solvent for refocusing said nuclear spin transferred to the solvent by chemical exchange; - applying a second magnetic field gradient pulse to thereby select the excitation in the nuclear spin; and - performing a measurement of the excitation in the nuclear spin excited by the first radiofrequency pulse at the resonance frequency of the solute and refocused with the refocusing radiofrequency pulse at the resonance frequency of the solvent, wherein the second magnetic field gradient pulse and the first magnetic field gradient pulse have the same gradient pulse area or a gradient pulse area deviating by 10% or less, preferably 1% or less. encoding an excitation in a nuclear spin of the solute comprising at least one preparation sequence, wherein said preparation sequence comprises the steps of: - applying a first radiofrequency pulse to the nuclear spin at a resonance frequency of the solute; and - applying a first magnetic field gradient pulse suitable for changing a phase of the nuclear spin; and - applying a first radiofrequency pulse to the nuclear spin at a resonance frequency of the solute; and - applying a first magnetic field gradient pulse suitable for changing a phase of the nuclear spin; and measuring the excitation in the nuclear spin, said measuring including the steps of: - applying a refocusing radiofrequency pulse at a resonance frequency of the solvent for refocusing said nuclear spin transferred to the solvent by chemical exchange; - applying a second magnetic field gradient pulse to thereby select the excitation in the nuclear spin; and - performing a measurement of the excitation in the nuclear spin excited by the first radiofrequency pulse at the resonance frequency of the solute and refocused with the refocusing radiofrequency pulse at the resonance frequency of the solvent, - applying a refocusing radiofrequency pulse at a resonance frequency of the solvent for refocusing said nuclear spin transferred to the solvent by chemical exchange; - applying a second magnetic field gradient pulse to thereby select the excitation in the nuclear spin; and - performing a measurement of the excitation in the nuclear spin excited by the first radiofrequency pulse at the resonance frequency of the solute and refocused with the refocusing radiofrequency pulse at the resonance frequency of the solvent, wherein the second magnetic field gradient pulse and the first magnetic field gradient pulse have the same gradient pulse area or a gradient pulse area deviating by 10% or less, preferably 1% or less.