<unk>  (Na2C4H4O6) is used as an emulsifier and a binding agent in food products such as jellies, margarine, and sausage casings.  As a food additive, it is known by the E number E335.
Because its crystal structure captures a very precise amount of water, it is also a common primary standard for Karl Fischer titration, a common technique to assay water content.
Sodium tartrate
Potassium acetate
Potassium canrenoate
Calcium chloride
Emepronium
Magaldrate
Dolasetron 
Sodium chloride