Sodium tartrate

Sodium tartrate (Na2C4H4O6) is a salt 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.