Hey Hamid,

I would dissolve the compound in a deutered solvent (such as CDCl3, CD3OD, D2O, or DMSO). There is no need to add extra water. If your sample dissolves easily in water, the solvent of choice would be D2O. If you are preparing the sample by yourself, you may need to add TMS (for organic solvents) or DSS and TSP (aqueous. solvents) for the NMR chemical shift reference.

• Here is the well-written, step-by-step instruction for NMR sample preparation:

https://www.cif.iastate.edu/sites/default/files/uploads/NMR/Manuals/NMR_Sample_Prep.pdf

• In this article, you may read more about various NMR solvents and their inpurities:

Article NMR Chemical Shifts of Common Laboratory Solvents as Trace Impurities

• And in this paper, you may get familiar with probe preparation of MR contrast agent, that can used to evaluate the T1 and T2 relaxation times

Article Preparation and In Vitro Characterization of Dendrimer-based...

All the best,

Rafal

You don't mention what you are wanting to see in your NMR test. Rafal's recommendation is good if you are wanting to get a hydrogen NMR spectrum, but you say your sample is intended to be an MRI contrast agent and it also doesn't sound like it contains any hydrogen, so I am guessing that what you really want is to measure the impact on water T1 and T2. If this is the case, you will want to dissolve your sample in H2O. You will also want to add a phosphate buffer, to maintain a physiologically relevant pH and heat your sample to 37°C, since both pH and temperature impact relaxation times.

Good Luck!