Establishing the Lock for Paramagnetic Samples

Paramagnetic samples often have very broad lines and lines at unusual chemical shifts. The paramagnetic solute may also affect the width and frequency of the deuterium resonance signal of the solvent used to establish the lock. For this reason an "autolock" and "autoshim" procedure may not work. In such cases the lock signal must be searched for manually. If you are not sure how to do this, please seek help in the NMR lab.