A citrate can refer either to the conjugate base of citric acid, (C3H5O(COO)33−), or to the esters of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.
Read more about Citrate: Other Citric Acid Ions, Acidity, Buffering, Chelating, Metabolism, Fatty Acid Synthesis