monosodium glutamate is extremely soluble in water. You can use it for chemistry just as glutamic acid, just add exactly 1 equivalent of acid. For example if you add excess of diluted sulfuric acid and then 1 equiv of NaNO2 at 0C, you get (S)-gamma-butyrolactone-5-carboxylic acid. You would need to extract it from the acidic aqueous phase with some solvent, and evaporate it.

Another convenient preparation is pyroglutamic acid, you just mix concentrated sodium glutamate solution with exactly 1 equivalent of strong acid (HCl for example) and reflux the mixture for 2 days in water. You remove unreacted glutamic acid by passing the solution through strongly acidic ion exchanger in acid form (it binds to the ion exchanger) and repeatedly extract the eluates with ethyl acetate to get pyroglutamic acid.